The use of apple cider vinegar as a home remedy dates back centuries. Over time, it has been used as a cooking ingredient, a cleansing agent, a disinfectant and an ancient remedy for curing a wide variety of ailments. In recent years, apple cider vinegar has become recognized by many people as a powerful health tonic. But how does it really impact your health? The answer may surprise you.
Apple cider vinegar consists of vitamins, mineral salts and amino acids. The main ingredient of apple cider vinegar, acetic acid, is responsible for vinegar's bitter taste and strong odor. To make this type of vinegar, apples are pulverized and then left to ferment. During fermentation, bacteria and yeast enzymes break down the sugar in the apples to create alcohol. Vinegar is created when the alcohol continues to ferment.
There are two basic kinds of apple cider vinegar: commercially produced vinegar that's found in the cooking aisle of supermarkets, and natural, raw and sometimes organic vinegar that's found in health food stores. In terms of health benefits, you'll want to use the raw, natural variety to achieve the best effects.
Apple Cider Vinegar as an Immune System Booster
There are many ways in which apple cider vinegar may be responsible for a boost in immune system health. Full of vitamins and minerals, apple cider vinegar helps provide vital nutrients that your body may be missing. Raw apple cider vinegar contains anti-fungal, anti-viral and anti-bacterial properties that can work as immune protectors against a wide variety of germs. In addition, apple cider vinegar may help balance pH levels in your body and maintain your body's natural alkaline state, in which it's better equipped to stave off colds and other viruses.
Apple Cider Vinegar to Improve Metabolism and Weight Loss
Apple cider vinegar as a weight-loss supplement is nothing new. Weight loss is one of the most common reasons people turn to apple cider vinegar, and for years, people have relied on its health benefits to help trim their waistlines. The acetic acid in the vinegar reacts with foods that are eaten in a way that may help to boost iron absorption. When iron is absorbed at a high rate, oxygen is utilized rather quickly, and the result is a higher metabolic rate. A higher metabolic rate leads to increased weight loss as a result of more calories being burned.
Although apple cider vinegar has thousands of supporters who swear by the weight-loss benefits, there are no scientific studies that prove these claims to be true. Some research over the years has suggested that apple cider vinegar may have a possible weight-loss link, although more studies need to be conducted.
Apple Cider Vinegar to Improve Digestion
It's the combination of acids and minerals found in apple cider vinegar that's associated with improved digestion. Though the exact reason is unknown, one popular theory suggests that the acids and minerals together help prevent bacteria from developing and breeding in the digestive tract. Bacteria in the digestive tract are a cause of slowed digestion and digestive illnesses. When the minerals in apple cider vinegar form a bond with the acids, they may become neutralized, which balances out the digestive tract.
Apple Cider Vinegar to Remove Toxins
Next to weight loss, detoxification is one of the most popular reasons why people turn to raw apple cider vinegar. For years, people have relied on apple cider vinegar and its cleansing properties to remove toxins and impurities from their bodies. To date, no scientific studies have been able to prove those cleansing properties. Still, many people believe that apple cider vinegar may assist with detoxification by aiding circulation and may boost the liver's ability to purge toxins.
Once again, it's the acids found in apple cider vinegar that are believed to be responsible for the cleansing effects. The acids may help to eliminate impurities by binding to free radicals and other toxins that are stored in the blood, fat cells and organs and pulling them out of the body. However, it's certain that apple cider vinegar supplies people's bodies with a large number of vitamins, minerals and enzymes, all of which are essential to a body that's purging out toxins.
Apple Cider Vinegar for Skin Benefits
Apple cider vinegar is touted as a natural remedy for a wide variety of skin conditions. From removing warts and freckles to treating acne and soothing the pain of sunburn, its use as a topical treatment is widespread. While supporters insist on apple cider vinegar's ability to improve skin health, there are only a few scientific studies that support this popular theory. The few that have been conducted suggest that although apple cider vinegar may help with conditions such as shrinking warts, treating lice and dandruff, and eliminating acne, it won't help as quickly or as effectively as traditional medications. Therefore, relying only on apple cider vinegar as a treatment isn't recommended.
Apple Cider Vinegar to Control Blood Sugar
Current studies aim to analyze whether apple cider vinegar may treat diabetes and lower blood sugar. The underlying reason for apple cider vinegar's effect on glucose is not yet understood. It's important to note that individuals living with diabetes should never start an apple cider vinegar regimen without a doctor's supervision. Any use of apple cider vinegar in diabetics should be closely monitored by a healthcare practitioner.
Apple Cider Vinegar for Lower Blood Pressure and Improved Heart Health
Natural health enthusiasts claim that apple cider vinegar can have a positive effect on elevated cholesterol levels and high blood pressure. Not many studies have been performed on the effects apple cider vinegar may have on high cholesterol. The few that have been performed suggest that the vinegar may help lower cholesterol, but more research needs to be conducted. The same thing goes for apple cider vinegar and blood pressure. If there is, in fact, a correlation between apple cider vinegar and decreases in blood pressure and cholesterol — two of the major factors in heart disease — then future research should aim to unravel the relationship between taking apple cider vinegar daily and improvement of overall heart health.
Non-alcoholic fatty liver disease (NAFLD) is recognized as the most common chronic liver disease globally, with almost 25% prevalence in the general population (1). In the early 2000s, the prevalence of NAFLD in China was 23.8% and reached 32.9% in 2018, which was responsible for over a third (37%) of the incidence of central obesity or diabetes (2, 3). Without intervention, NAFLD may progress from simple hepatic steatosis to advanced steatohepatitis, even to fibrosis, cirrhosis, and hepatocellular carcinoma (4). Therefore, identifying approaches to prevent NAFLD is one of the public health problems that need to be solved urgently.
Previous studies have reported the impact of oxidative stress and inflammation on NAFLD (5–7). Vitamin C (VC), as an effective water-soluble antioxidant, has a scavenging effect on excessive free radicals in the body and a protective effect on tissue damage caused by oxidative stress, and it probably plays a protective role against NAFLD (8, 9). The association between dietary VC intake and NAFLD has been studied, but not extensively, and with conflicting results (10–13). Han et al. revealed a significant positive association between low VC intake and NAFLD in the male population in a cross-sectional study (11). In contrast, another small sample cross-sectional study suggested that both dietary VC intake and plasma VC concentration were of similar levels between patients with NAFLD and healthy controls (12). Moreover, the clinical burden of NAFLD is not only confined to liver-related morbidity and mortality, but NAFLD is a multisystem disease affecting extrahepatic organs and regulatory pathways (14). Epidemiological studies have also shown an association between VC status and reduced insulin resistance and improved blood glucose control (15–17). Meanwhile, higher plasma VC was associated with a lower risk of developing type 2 diabetes (T2DM) (18). A previous study suggested that supplementation of the diet with kiwifruit, which is rich in VC, enhanced plasma VC status and also decreased the HbA1c levels (19). A recent meta-analysis investigating VC supplementation and insulin resistance found that doses of ≥200 mg/day VC significantly reduced glucose concentrations in patients with T2DM, mainly if the intervention was for more than 30 days and in older individuals (20).
However, the possible mechanisms of VC in improving liver health and glucose metabolism remain unclear. Adiponectin, which exerts marked insulin-sensitizing and anti-inflammatory effects (21), has been reported to be involved in the pathogenesis of non-alcoholic fatty liver, and a previous study demonstrated that a decrease in adiponectin levels is an independent risk factor of developing NAFLD (22, 23). Interestingly, our previous study and other study showed that VC treatment could increase the secretion of high molecular weight (HMW) adiponectin from human hepatocytes and adipocytes (24, 25). In addition to having lower levels of adiponectin, patients with NAFLD also have increased intestinal permeability and the changes in intestinal microbiota may also be the driving force for the progress of NAFLD (26–29). However, the effect of VC on the intestinal microbiota is unclear.
By now, no studies have been performed to determine whether VC alone has a causal effect on liver function and glucose homeostasis parameters in patients with NAFLD. Therefore, in this double-blind, randomized controlled trial (RCT), we aimed to find out whether VC supplementation could improve liver function and other associated metabolic markers in NAFLD individuals and explored possible mechanisms.
Patients and Methods
Patients
From March to May 2020, patients with NAFLD aged 18–60 years old and who have lived in Xianyang for more than 10 years were recruited from the Medical Examination Center of Xianyang Central Hospital, Xi'an, Shaanxi, China. Patients who were newly diagnosed with NAFLD were included (30). Patients affected by hepatitis B and C, and those with cardiac, renal, hyperuricemia, hyperoxaluria, hemochromatosis, autoimmune, cirrhosis, and other metabolic diseases were excluded. Exclusion criteria also included insulin treatment, smoking habits, alcohol intake (>20 g/day), other antioxidant supplements or medications taking in the past 3 months, recreational or statins drug use, and exposure to environmental toxins known to induce liver steatosis. According to the sample size calculation formula, the number of cases required for each group was 25. Taking a dropout rate of 20% into consideration, at least 90 volunteers will be recruited. Overall, 98 participants were enrolled in the study. This trial was registered at ClinicalTrials.gov (http://www.chictr.org.cn); Identifier: ChiCTR2000033171. The study was consistent with the ethical guidelines of the Helsinki 1975 Declaration and was approved by the Ethics Committee of Xi'an Jiaotong University and Xianyang Central Hospital. Signed informed consents were obtained from all the participants, and all of them were told that there is no need to change eating habits except for the intervention.
Study Supplements and Allocation
Participants were assigned to one of three different treatment groups using stratified randomization. Randomization was stratified by gender, age, weight, body mass index (BMI), and waist circumference. Based on the Chinese Residents' Dietary Guidelines, the proposed intake for chronic non-communicable diseases (PI-NCD) is 200 mg/day for adults (31). Since it was tough to produce a placebo with the same taste as VC (Blackmores, Australia), the Low (dose) group took one tablet of VC (250 mg/day) per day, and the High group was supplemented with 2,000 mg/day, which is the tolerable upper intake level. The Medium group was also designed and assigned to 1,000 mg/day of VC. Participants were asked to take or chew the supplements before meals. During the 12 weeks intervention time, they were also asked to visit the intervention staff every 2 weeks where their clinical symptoms and side effects from VC supplementation were assessed, compliance was checked based on the number of unconsumed tablets, and tablets for further use were dispensed. In addition, subjects were instructed to maintain the same lifestyle and diet during the trial as usual.
Procedures
Participants were asked to provide demographic information and completed self-administered diet and physical activity questionnaires before the intervention. Anthropometric parameters (body weight, height, and waist and hip circumferences) and systolic and diastolic blood pressures were assessed according to standard methods. BMI was calculated as body weight divided by height squared (kg/m2). Fasting blood was collected at baseline and week 12 by an antecubital venous puncture. Serum or plasma samples were centrifuged at 1,500 g for 15 min at 4°C and frozen at −80°C. Plasma VC content was detected by 1,290 Infinity Ultrahigh-Performance Liquid Chromatography (UHPLC) from Agilent Company in Guangzhou KingMed Center for Clinical Laboratory Co., Ltd., Guangdong Province, China. The detection method has been described in detail previously (32). Briefly, the samples were pretreated by protein precipitation, centrifugation, etc. Then, the processed samples were introduced into the UHPLC system with the mobile phase and then chromatographically separated to reach the diode array detector. Finally, the VC concentration was calculated by the strength of the signal response. All other blood indicators associated with the liver function such as total protein (TP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (γ-GT), alkaline phosphatase (ALP), total bilirubin (TBIL), serum indirect bilirubin (IBIL), serum direct bilirubin (DBIL), total cholesterol (TC), and triglyceride (TG) were tested twice in parallel using Hitachi 7600 automatic biochemical analyzer (Hitachi, Tokyo, Japan) to obtain the average value. Plasma human total and HMW adiponectin were measured using ELISA test kits purchased from Abcam in the United Kingdom (Cat. # ab99968) and MERCK, Germany (Cat. # EZHMWAN-65K), respectively. Finally, the absorbance (Optical Delnsity, OD value) was measured at a wavelength of 450 nm with a microplate reader to calculate the concentration.
We also collected the feces of volunteers from the Low and Medium groups at baseline and week 12 for 16S rDNA Amplicon Sequencing (Novogene Company, China). Operational taxonomic units (OTUs) clustering and species classification analysis based on the clean data obtained by sequencing were performed. According to the OTU clustering results, species annotations were made on the representative sequence of each OTU, and the corresponding species information and species-based abundance distribution were obtained. At the same time, the abundance, alpha diversity calculation, Venn map, and petal map analysis of OTUs were performed to obtain the species richness and uniformity information among different samples or groups.
Statistical Analysis
Differences in baseline measurements among groups were assessed using the chi-squared test for categorical variables and variance tests for continuous measures. The one-way ANOVA test and the Student–Newman–Keuls test were used to determine the significance of the difference. In non-parametric analyses, the significance of the changes within and between groups was assessed by the Wilcoxon rank-sum test. Analyses were carried out using SPSS software (version 24) (SPSS Inc., Chicago, USA). Significance was defined as P < 0.05 (two-tailed).
Results
Baseline Characteristics
Of 98 subjects enrolled, 84 completed the study (Figure 1). A total of 14 subjects terminated early. Five withdrew due to personal reasons, four lost due to inconvenience, and five were lost to follow-up. The samples of the stool of volunteers were collected before and after the intervention. Only 12 people, 6 from the Low group and 6 from the Medium group, provided samples both before and after the intervention. The mean age of participants was 40.6 years, and 58.3% were women. The fasting glucose, lipids, and plasma VC status were comparable among the three groups at baseline (Table 1). After the intervention, plasma VC levels were significantly elevated in the Medium group (before 56.67 ± 19.27 vs. after 49.28 ± 15.82, P = 0.032) and the High group (before 64.40 ± 19.06 vs. after 50.27 ± 16.03, P = 0.007; Figure 2). Interestingly, men had lower plasma VC levels before the intervention than women (men 39.90 ± 13.73 vs. women 55.55 ± 13.64, P < 0.001). Nevertheless, after the intervention, there was a remarkable increase in the men among the three groups (P = 0.024). There was also an increase of plasma VC levels in the women before and after the intervention, but without static significance (P = 0.018; Supplementary Figure 1).
Figure 1. Flow diagram of participant progress through the study. 1means nine participants provided samples before the intervention, three participants lose after the intervention, six participants from the Low group provided samples both before and after the intervention finally. 2means seven participants provided samples before the intervention, one participant lose after the intervention, six from the Medium group provided samples both before and after the intervention finally. 3means five participants provided samples before the intervention, all participants lose after the intervention, there are no complete samples finally in the High group.
Table 1. Baseline characteristics of participantsa.
Figure 2. Plasma VC levels before and after the intervention in all three groups, respectively. (A) means Low dose group, (B) means Medium dose group, (C) means High dose group. Black means VC plasma concentration (μmol/l) before the intervention, gray means VC plasma concentration after the intervention; paired t-test used to test the difference before and after the intervention in three groups. VC, vitamin C.
Positive Modulatory Effect on Liver Function
As shown in Table 2, after the intervention, some serological indicators of the three groups all improved statistically. First, in the low group, compared with baseline, the AST, ALP, TBIL, and DBIL indexes of the Low group decreased. In the Medium group, AST, ALT, γ-GT, ALP, and DBIL indexes decreased. In the High group, the levels of γ-GT, ALP, TBIL, DBIL, and triglycerides also decreased. Second, compared among groups, the changes of all the liver function indicators were similar except for ALT and AST, whose P-values were close to 0.05. Further comparison of specific differences between groups showed that compared with the High group, the Medium group had a more significant decrease in AST [Medium, −5.00 (−10.25, −1.75) vs. High, −2.50 (−7.75, 0.00), P = 0.02]. Medium group had a more significant decrease in ALT [Medium, −8.00 (−18.00, −1.75) vs. High, −3.50 (−13.75, 4.25), P = 0.05; Medium, −8.00 (−18.00, −1.75) vs. Low, −3.00 (−9.00, 5.50), P = 0.031]. However, there was no statistically significant difference in ALT or AST between the Low and the High groups.
Table 2. Metabolic indicators change during the triala.
Effects on Glucose Metabolism
After the intervention, blood glucose metabolism status statistically significantly improved in all three groups (Figure 3). The blood glucose levels were significantly decreased in the Medium group (before 5.05 ± 0.51 vs. after 4.75 ± 0.53, P = 0.002) and the High group (before 5.26 ± 0.80 vs. after 4.88 ± 0.98, P = 0.004), while the insulin levels of participants in all the groups reduced obviously [Low (before 22.24 ± 12.50 vs. after 15.92 ± 10.27, P < 0.001); Medium (before 19.22 ± 14.54 vs. after 8.46 ± 7.55, P < 0.001); High (before 22.24 ± 21.1 vs. after 10.54 ± 12.45, P < 0.003)]. However, there was no difference among groups (glucose, P = 0.753; insulin, P = 0.389; data not shown). Notably, there was a remarkable decrease in homeostasis model assessment for insulin resistance (HOMA-IR) among the three groups, especially the Medium group (before 4.61 ± 3.51 vs. after 2.62 ± 2.41, P < 0.001; Table 2). Then, we also detected the HWM adiponectin and total adiponectin levels of patients and found a significant elevation after the intervention with VC in all groups [total adiponectin, Low (before 41.77 ± 33.26 vs. after 110.41 ± 74.87, P < 0.001), Medium (before 30.57 ± 17.93 vs. after 78.48 ± 50.24, P < 0.001), High (before 43.57 ± 18.76 vs. after 70.29 ± 48.25, P < 0.001); HWM adiponectin, Low (before 2.49 ± 1.73 vs. after 8.79 ± 4.69, P < 0.001), Medium (before 4.18 ± 2.54 vs. after 9.09 ± 4.31, P < 0.001), High (before 2.57 ± 3.65 vs. after 9.70 ± 5.49, P = 0.004)]. However, the elevation of both total and HMW adiponectin was not remarkable among the groups (data not shown) (Figure 4).
Figure 3. Fasting blood glucose levels (A, Low dose group; B, Medium dose group; C, High dose group) and insulin levels (D, Low dose group; E, Medium dose group; F, High dose group) before and after the intervention in all three groups, respectively. Black means glucose or insulin plasma concentration (mmol/l, mIU/l) before the intervention, gray means glucose or insulin plasma concentration after the intervention; paired t-test used to test the difference before and after the intervention in the three groups.
Figure 4. Total adiponectin (A, Low dose group; B, Medium dose group; C, High dose group) and HWM adiponectin levels (D, Low dose group; E, Medium dose group; F, High dose group) before and after the intervention in the three groups, respectively. Black means total adiponectin or HWM adiponectin plasma concentration (μg/ml) before the intervention, gray means total adiponectin or HWM adiponectin plasma after the intervention; paired t-test used to test the difference before and after the intervention in all three groups.
Changes in the Intestinal Microbial Community
For the 16S rRNA sequencing of the intestinal microbiota of patients with NAFLD, there were six volunteers in the Low and the Medium groups, respectively, and 24 fecal biological samples were collected. The alpha diversity analysis indicated that all the four diversity indexes (ACE, Shannon, chao1, and Simpson) in the two groups showed an upward trend (Figure 5). For species community analysis (Figure 6), compared with the control group (250 mg/day), the Bacteroides level in the middle-dose group declined, the Firmicutes rose, and the proportion of Firmicutes and Bacteroides (Firmicutes to Bacteroidetes, F/B) decreased.
Figure 5. Analysis and comparison of multiple indexes before and after the intervention in the Low and the Medium groups. The study of microbial diversity in community ecology can reflect the abundance and diversity of microbial communities through a single sample diversity analysis [α(alpha) diversity], including a series of statistical analysis indexes to estimate the species abundance and diversity of environmental communities diversity. The picture showed the four indexes [ACE (A), shannon (B), chao1 (C), and simpson (D)] of the α diversity analysis of 6 subjects in the Low group and Medium group respectively before and after the intervention. The higher the values of the four indexes, the more abundant species in the community. Low1 means before the intervention in the low-dose group, Low2 means after the intervention in the low-dose group, Medium1 means before the intervention in the medium-dose group, and Medium2 means after the intervention in the medium-dose group.
Figure 6. Analysis and comparison of relative abundance of top 10 before and after the intervention in the Low and the Medium groups at phylum, class, order, and genus level. The higher the relative proportion, the more abundance in the community at different biological classification level. (A) means phylum level; (B) means class level; (C) means order level; and (D) means genus level.
Discussion
In this study, we observed that oral VC supplementation improved liver health and glucose metabolism in patients with NAFLD. The intake of 1,000 mg/day VC showed a profound effect. Vitamin C supplementation increased plasma VC, adiponectin, HMW adiponectin levels, and the diversity of intestinal microbiota. Furthermore, decreased the majority of parameters associated with liver function, fasting glucose level, and HOMA-IR. Among the participants, men were likely to get more benefits from the supplementation.
Regarding the nutritional risk factors, excessive energy intake but relatively minor intake of micronutrients contributes more to NAFLD (33). Hence, lifestyle changes and antioxidant therapy are widely used to prevent and treat NAFLD (34). Among antioxidants, vitamin E is now widely recommended clinically at present. The largest trial by now revealed that vitamin E treatment showed a superior effect than pioglitazone on improving histological and biochemical features in subjects with non-alcoholic steatohepatitis (NASH) (35). However, vitamin E would increase insulin resistance and plasma triacylglycerols when administered for 2 years and even was associated with excess mortality in primary and secondary prevention trials (36, 37). Compared with fat-soluble vitamin E that can accumulate after long-term use, VC is water-soluble and remarkably safe, even at 10–100 times the recommended dietary allowance when taken orally (38). Some previous studies have indicated that the combined supplementation of VC and other nutrients, such as vitamin E or resveratrol, can alleviate hepatic steatosis, but the effect of VC alone on liver function was still not apparent (39, 40). Animal experiments showed that VC was involved in regulating circulating and hepatic lipids homeostasis (41). In mice, a moderate dose (30 mg/kg/day) was beneficial for the preventing and treating of NAFLD caused by a high-fat diet (42). Although the epidemiological study also supported the association between inadequate VC intake and NAFLD, there is no direct evidence that can prove the benefits of supplementing VC on patients with NAFLD (43). In our study, we found that 12 weeks of VC intervention remarkably improved the indicators of liver function in patients with NAFLD. Our results suggested that as adjuvant therapy for daily health prevention and improvement of prognosis of NAFLD, routine supplementation of VC can help the recovery of liver function.
Non-alcoholic fatty liver disease is associated with an increased risk of cardiovascular disease, dyslipidemia, and T2DM in adults (44, 45). Several hypotheses were generating to understand the metaorganism pathways that influence the development and progression of NAFLD. What has been determined is that it is strongly associated with obesity and insulin resistance (46–48). Consistently, in this study, we also observed that all the patients were overweight, and their waist circumferences were very close to the cut-off point according to the Chinese standard. Since all participants were asked to keep their dietary habits, they had rare weight changes no matter how much VC was administered. In terms of glucose homeostasis, we found the fasting plasma insulin levels were close to the upper level of normal standard, even though their fasting glucose levels were still normal. It appeared likely that those patients had a high risk of getting the possibility to progress to T2DM soon, which was consistent with the epidemiological fact that patients with NAFLD are more likely to develop other metabolic diseases, especially T2DM (49). Interestingly, our results showed that 12 weeks of VC supplementation improved the glucose metabolism of patients. Specifically, fasting plasma insulin and glucose contents (except for the Low group) were all reduced after the intervention markedly, accompanied by a lower degree of insulin resistance. Similarly, the most favorable effect was still seen in the Medium group. Although it was hard to tell the causal relationship between the recovery of liver function and improved glucose metabolism, our results at least indicated that the intervention of VC would decelerate the disease progression of patients with NAFLD.
Previous studies suggested that adiponectin, which has many favorable effects on metabolic diseases, may be involved in the pathogenesis of NAFLD (22, 23). Our previous study showed that VC pretreatment might be a new treatment method of NAFLD/NASH through attenuate hepatocyte stress induced by TNFα via activation of the FGF21/FGFR2/adiponectin pathway (24). Expectedly, in this study, after the intervention, even at the smallest dose (250 mg/day), total adiponectin and HWM adiponectin levels showed a significant upward trend, which may contribute to the improvement of both liver function and glucose metabolism in patients with NAFLD. To the best of our knowledge, this is the first time to report the effect of VC supplementation on adiponectin production in human individuals, which is of great significance to clarify the protective role of VC in NAFLD. More interestingly, we found that the men seemed to get more benefits from VC supplementation than the women. This finding may be explained by the truth that men generally consume fewer fresh vegetables and fruits daily than the women at baseline (data not shown), and their initial VC levels were lower. Our findings were consistent with a recent study that showed that the inverse association between dietary VC intake and NAFLD in middle-aged and older adults was stronger in the male population (10).
Gut microbiota and gut-liver axis dysfunction are critical for NAFLD progression and the development of more severe inflammatory and fibrotic stages NASH (50). Several studies have suggested that in addition to changes in adiponectin, changes in the intestinal microbiota may also be the driving force for the progress of NAFLD (28, 29). Our research also found that taking 250 mg/day and 1,000 mg/day of VC daily for 12 weeks can improve the intestinal microbiota of patients with NAFLD by increasing the diversity of intestinal microbiota and the relative proportion of beneficial bacteria. Bacteroidetes and Firmicutes are the dominant "good" bacteria and "bad" bacteria, respectively. In the human intestinal tract, a person with NAFLD showed a higher Firmicutes to Bacteroidetes (F/B) ratio than a healthy population (51, 52). In this study, we found that only 1,000 mg/day of VC supplementation for 12 weeks increased the diversity of species and the dominant microbiota. Unfortunately, only 12 people from the Low and Medium groups provided stool samples. Although the sample size was small, our results hint that VC supplementation may produce beneficial effects on patients with NAFLD by affecting the intestinal microbiota, which may, in turn, promote liver function and other related metabolic parameters in patients with NAFLD through the gut-liver axis.
The main strength of our study was the randomized controlled design and stratification by age, gender, and BMI, which eliminates interindividual differences. Furthermore, our research filled the gap in the trial of VC intervention alone in patients with NAFLD and revealed the beneficial effects. However, there were also some limitations in our research. First, there was no placebo control in our study because it was challenging to make a placebo with the same odor and color as VC. Regardless, it was also appropriate to take a dose that is close to the PI-NCD of VC (200 mg/day) to meet the favorable principles in ethics. Second, due to the relatively small group of participants, the differences in couples of indicators regarding liver function were not significantly different though a good effect was present. To obtain more generalizable conclusions, more extensive population studies are still needed.
In conclusion, to our best knowledge, this is the first study that determined the effect of oral VC supplementation on patients with NAFLD. Daily supplementation with VC, especially 1,000 mg/day, can help promote liver function recovery and glucose homeostasis in patients with NAFLD.
Data Availability Statement
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
Ethics Statement
The studies involving human participants were reviewed and approved by the Ethics Committee of Xi'an Jiaotong University and Xianyang Central Hospital. The patients/participants provided their written informed consent to participate in this study.
Author Contributions
XLu, ZH, and XLi designed the research. ZH, HY, SW, ZX, PW, XG, WZ, and JG conducted the research. ZH, XLi, and HY analyzed the data and performed the statistical analysis. XLi, ZH, and XLu wrote the paper and had primary responsibility for the final content. All the authors read and approved the final manuscript.
Funding
This work was supported by the National Natural Science Foundation of China (Grant No. 81874263).
Conflict of Interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher's Note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Supplementary Material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fnut.2021.745609/full#supplementary-material
Abbreviations
NAFLD, nonalcoholic fatty liver disease; VC, vitamin C; RCT, randomized controlled trial; HMW, high molecular weight; AST, aspartate aminotransferase; ALT, alanine aminotransferase; γ-GT, gamma-glutamyl transferase; ALP, alkaline phosphatase; TBIL, total bilirubin; DBIL, direct bilirubin; HOMA-IR, homeostasis model assessment for insulin resistance; T2DM, type 2 diabetes; PI-NCD, proposed intake for chronic non-communicable disease; UHPLC, ultrahigh performance liquid chromatography; OTUs, operational taxonomic units; TG, triglycerides; NASH, nonalcoholic steatohepatitis.
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Photo Courtesy: The Good Brigade/DigitalVision/Getty Images
Hepatitis is a condition that causes inflammation of your liver. Currently, there are an estimated 6 million people living with hepatitis in the United States, and more than 50,000 people are diagnosed with this disease every year. There are three primary types of hepatitis, and while their symptoms can be similar, they vary largely in the ways they're transmitted. Learning more about each type of hepatitis can help you better understand the condition as a whole.
Hepatitis A is the most easily transmitted of the three viruses. It affects approximately 2,500 people every year in the United States. It typically spreads through feces-contaminated food or water and is found in the feces of people who have the virus. Hepatitis A causes a short-term, acute sickness that most people heal from without treatment. However, it can cause serious illness in some people. This virus is more common in places with underdeveloped sanitation systems.
While doctors can't treat hepatitis A with medication, people who get this virus can manage its symptoms with fluids, rest and good nutrition. There's also a safe and effective vaccine available to protect you against hepatitis A.
What Is Hepatitis B?
Hepatitis B can occur both acutely (meaning it develops quickly and lasts a short time) and chronically (meaning it develops slowly over time and worsens over months or years). According to the Centers for Disease Control and Prevention, up to 2 million people in the United States are chronically affected with hepatitis B. Hepatitis B can be transmitted through sexual activity and exposure to infected blood. It can also be passed from a parent to their newborn child during birth.
Hepatitis B usually causes short-term discomfort that many people recover from completely after about four to eight weeks. However, it can turn into a chronic condition that lasts for years; this is more likely in older adults. Doctors can treat severe chronic hepatitis B with antiviral medications. However, in most cases, treatments focus on proper hydration and nutrition. There's a safe vaccine available to protect you against hepatitis B, too.
What Is Hepatitis C?
Photo Courtesy: BSIP/Getty Images
Approximately 4 million people in the United States are affected with hepatitis C. This form of hepatitis causes a chronic illness in over 50% of people who get this type of the virus. It's the least transmissible of the three viruses and can spread through contact with infected blood.
Hepatitis C occurs more commonly in people who engage in intravenous drug use. If you received a blood transfusion before 1992, you should also get tested for hepatitis C if you haven't previously. Hepatitis C can spread through unprotected sexual intercourse, but this is a less common way to transmit it. While there's no vaccine for chronic hepatitis C, treatments that are available today offer a 95% cure rate.
Chronic hepatitis C can significantly affect how your liver works. It can cause cirrhosis, which means that your normal liver tissue is replaced with scar tissue. It can also cause liver cancer. However, there are medications that can help keep this disease in check. Making lifestyle changes, such as reducing or eliminating alcohol from your diet, can also decrease your chances of experiencing complications. In severe cases, hepatitis C may require a liver transplant.
The varying forms of viral hepatitis affect millions of people in the United States. Chronic hepatitis often has few symptoms in its early stages, so recognizing the associated dangers and getting tested if you've been exposed may save your life. Although there are five types of viral hepatitis, only A, B and C are the forms commonly found in the United States.
Resource Links:
"Hepatitis A, B, and C: Learn the Differences," Immunization Action Coalition
"What's the Difference Between Hepatitis A, B and C?," UNC Health Talk
"The ABCs of Hepatitis," Centers for Disease Control and Prevention
"What's the Difference: Hepatitis B vs Hepatitis C?," Hepatitis B Foundation
Vitamin C, also called ascorbic acid, is a water-soluble vitamin. Water-soluble vitamins are stored in the body in very limited amounts, and are excreted through the urine. Therefore, it is a good idea to have them in your daily diet. Vitamin C is sensitive to light, heat, and air and can be destroyed during food preparation, cooking, or storage.
Functions
Vitamin C's functions include:
Acting as an antioxidant in the body
Playing a major role in collagen formation
Assisting in the synthesis of a neurotransmitter, norepinephrine
Helping break down cholesterol and synthesize bile
Playing a role in the absorption, metabolism, and utilization of other nutrients, such as folate, calcium, and iron
Promoting healing of wounds
Recommended Intake:
Age Group (in years)
Recommended Dietary Allowance (mg/day) [milligrams per day]
Females
Males
1-3
15
15
4-8
25
25
9-13
45
45
14-18
65
75
14-18 Pregnancy
80
n/a
14-18 Lactation
115
n/a
19-50
75
90
19-50 Pregnancy
85
n/a
19-50 Lactation
120
n/a
50+
75
90
Vitamin C Deficiency
Intakes of less than 10 mg per day of vitamin C can result in scurvy. Symptoms of vitamin C deficiency include:
Bleeding gums
Easy bruising
Impaired wound and fracture healing
Joint pain and swelling
Loose and decaying teeth
Hair loss
Fatigue
Bone pain and fractures
Vitamin C Toxicity
The tolerable upper intake level (UL) for vitamin C from dietary sources and supplements combined is:
Ages 1-3: 400 mg/day
Ages 4-8: 650 mg/day
Ages 9-13: 1,200 mg/day
Ages 14-18: 1,800 mg/day
Ages 19+: 2,000 mg/day
Because excess vitamin C is excreted in the urine, toxicity is rare. It can happen though, with several large doses throughout the day. Symptoms of vitamin C toxicity include:
Nausea
Excessive urination
Diarrhea
Abdominal cramps
Formation of kidney stones in susceptible people
Major Food Sources
Strawberries
Broccoli
Kiwi
Oranges
Green or red peppers
Cantaloupe
Tomato juice
Avacado
Baked potato
Green peas
Spinach
Health Implications
Populations at Risk for Vitamin C Deficiency
The following populations may be at risk for vitamin C deficiency and may require a supplement:
People who smoke cigarettes—Due to an increased metabolic turnover of vitamin C, smokers have lower blood vitamin C levels. It is recommended that smokers take 35 mg more per day than the applicable RDA.
People who drink excessive amounts of alcohol—This may, in part, be due to a nutritionally inadequate diet.
The elderly—Studies have shown that older adults have lower levels of serum vitamin C. This may be due to a diet lacking in essential nutrients.
Infants—Feeding babies evaporated or boiled milk can cause vitamin C deficiency. This is because heat can destroy the vitamin C found in cow's milk.
People with limited variety in their diet—People whose diets are affected by poverty; food faddists; and people with mental illness may not prepare meals that contain a variety of foods to obtain enough vitamin C.
People with malabsorption and certain chronic diseases—Those with certain medical conditions like severe intestinal malabsorption, renal disease, or cancer may not be able to absorb enough vitamin C.
Antioxidant Capabilities
Free radicals are normal by-products of metabolism, but they can cause chain reactions that result in cell damage. This cell damage can, in turn, increase the risk of chronic diseases, including certain forms of cancer and cardiovascular disease.
Antioxidants have the ability to stop this chain reaction. Vitamin C functions in the body as an antioxidant. Because of this antioxidant capability, vitamin C is being studied for a possible role in prevention of certain conditions like age-related macular degeneration, cataracts, cancer, and cardiovascular diseases. Currently there is not sufficient evidence to recommend vitamin C for any of these conditions.
Respiratory Infections
Many people believe that taking mega-doses of vitamin C will cure a cold. There is no scientific evidence to support this idea in the general population. However, there may be some preventative benefit in people exposed to extreme physical stress, cold environments, or those not getting enough vitamin C normally. Studies have found that taking vitamin C daily may help slightly reduce the symptoms and the duration of a cold. But taking vitamin C after the onset of the cold does not appear to effect the course of the illness. In addition, a review of studies on vitamin C found that it may be able to prevent and treat pneumonia, particularly in people who do not get enough vitamin C in their diet.
Tips For Increasing Your Vitamin C Intake:
To help increase your intake of vitamin C:
Serve fruits and vegetables raw whenever possible.
Leave the skin on potatoes and sweet potatoes.
Add sliced strawberries, mango, or kiwi to your breakfast cereal.
Use mashed avocado in place of mayonnaise as a sandwich spread.
Throw snow peas in your stir-fry.
Replace your morning coffee with a glass of orange or grapefruit juice.
If you take a vitamin supplement, make sure it contains vitamin C.
Resources
Choose My Plate—Department of Agriculture http://www.choosemyplate.gov
Eat Right—American Dietetic Association http://www.eatright.org
Canadian Resources
Canadian Digestive Health Foundation http://www.cdhf.ca
Dietitians of Canada http://www.dietitians.ca
References
Ascorbic acid. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 7, 2016. Accessed July 21, 2016.
Vitamin C. Office of Dietary Supplements National Institutes of Health website. Available at: https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional. Updated February 11, 2016. Accessed July 21, 2016.
Vitamin C. Oregon State University Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/mic/vitamins/vitamin-C. Updated January 14, 2014. Accessed July 21, 2016.
Vitmin C deficiency. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated April 27, 2010. Accessed July 21, 2016.
10/30/2009 DynaMed Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Hemila H, Louhiala P. Vitamin C for preventing and treating pneumonia. Cochrane Database Syst Rev. 2009;(3):CD005532.
Whether in the form of a fizzy drink or flavored lozenges, cold and flu preventative supplements almost always highlight vitamin C as one of their key ingredients. So, what's so magical about vitamin C? Also known as ascorbic acid, vitamin C is critical to living healthily. Since the human body cannot spontaneously generate this nutrient, vitamin C must instead be absorbed from outside sources, such as vitamin supplements or foods that are naturally rich in it.
Commonly found in cold and flu preventative supplements, vitamin C strengthens and speeds up immune system functionality. Though research does not indicate that vitamin C intake alone can prevent the onset of cold or flu, adequate daily intake may shorten the duration of an infection or lessen the severity of symptoms.
Vitamin C is crucial for the maintenance of well being. For example, it plays a role in wound healing and helps maintain many essential body tissues. It also acts as a potent antioxidant and can repair damage from free radicals, which are linked to aging effects, and disease vulnerability. Additionally, vitamin C can also prevent anemia, since it helps the body increase absorption of dietary iron, another vital mineral that the body cannot spontaneously create.
Foods that contain high concentrations of vitamin C have been linked with a lower risk of cardiovascular disease, like heart attack and stroke. Vitamin C can also increase levels of nitric oxide, a compound that widens blood vessels and, in turn, lowers blood pressure. In addition, regular intake of vitamin C, along with other vitamins, has been linked to a decreased risk for developing age-related cataracts, a leading cause of visual impairment in the United States.
Common Sources of Vitamin C
Vitamin C can be easily obtained through the many different foods, including:
Citrus fruits and juices (orange, grapefruit, lemon, lime and tangerine)
Berries
Melons
Mangoes
Kiwi
Tomato
Broccoli
Red peppers
Spinach
Squash
Potatoes
Cooking these foods may result in the loss of some of the vitamin content, so it is ideal to ingest them raw, either whole or juiced. Nowadays, there are also numerous packaged food products, like cereals, that have been enriched and fortified with vitamin C, so that the nutrient can be easily obtained.
Vitamin C may also be labeled as "L-ascorbic acid" in supplement form, and most over-the-counter multivitamins contain the recommended daily amount of the vitamin. While it is a good source when an individual is in need of a vitamin C boost, supplements are not meant to replace a diet rich in naturally derived vitamin C.
What Happens When You Have Too Much — or Too Little — Vitamin C?
Vitamin C is a water-soluble vitamin that can be easily flushed out of the body via urination when it is not needed. Therefore, if the main source of vitamin C is from naturally occurring foods, it is near-impossible for excess vitamin C to produce side effects. However, taking excessive concentrated vitamin C supplements may lead to diarrhea or stomach upset.
Since vitamin C-rich foods are so readily available nowadays, symptoms of inadequate vitamin C intake are also rare in the United States. However, malnourished individuals can experience symptoms of vitamin C deficiency over time, including:
Weakness
Fatigue
Anemia
Easy bruising
Joint pain
Skin breakdown
Weakened tooth enamel
Gum inflammation
Severe vitamin C deficiency is referred to as scurvy. Scurvy can be easily treated with increased dietary or supplemental vitamin C. Since vitamin C is crucial in the detoxification of the body, a lack of vitamin C can compromise the immune system and make an individual more susceptible to diseases and infections. Individuals with insufficient vitamin C may find that it takes longer than usual to recover from a cold or a physical wound.
Daily Dosage Recommendations:
The daily dosage recommendation for vitamin C is different for everyone, depending on factors such as gender, age, lifestyle and current health condition. The recommended daily dosage for vitamin C is at least 75 mg daily for women and 90 mg for men. Since people who are pregnant, breast feeding, smoking or using oral contraceptives have a lower blood level of vitamin C than others, larger doses of vitamin C may be needed to achieve optimal results in these individuals. Those who have prior or current medical conditions may also require bigger or smaller dosage levels, as recommended by their healthcare providers.
Resource Links:
"Vitamin C" via MedlinePlus
"Vitamin C and Infections" via MDPI
"Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials" via Hindawi, BioMed Research International
"Vitamin C" via National Institutes of Health
"Scurvy" via U.S. Department of Health & Human Services, National Institutes of Health
"Dietary intake and blood concentrations of antioxidants and the risk of cardiovascular disease, total cancer, and all-cause mortality: a systematic review and dose-response meta-analysis of prospective studies" via The American Journal of Clinical Nutrition
"Dietary vitamin and carotenoid intake and risk of age-related cataract" via The American Journal of Clinical Nutrition
"Cardiovascular System" via Department of Anatomy, Seoul National University College of Medicine (via Springer)
It's Fall which means flu season and a germy free-for-all — but we're on it! Here's our guide to staying healthy 'til Spring:
Schools are back in session, which means the common cold is not too far behind.
To avoid a cold or cut one short, you may be tempted to stock up on supplemental drink mix-ins like Emergen-C and Airborne for supposed cold-fighting ingredients like vitamin C or zinc. But do these unregulated powders and tablets actually work?
Unless you're a marathon runner, skier or soldier in extremely cold temperatures, extra vitamin C probably isn't going to keep you from getting sick. And children are most likely to benefit from zinc, but their parents? Not so much.
The basics
Vitamin C, or ascorbic acid, is an essential nutrient that helps the body's immune system, improves the body's absorption of iron, helps metabolize protein and regenerates antioxidants in the body. Too little of it will lead to scurvy, historically considered a sailor's disease because of the lack of access to fresh fruits and vegetables on long voyages. Too much of it can result in diarrhea, nausea, kidney stones and excess iron absorption.
Like most vitamins, the best way to consume this nutrient is via food: citrus, tomatoes, strawberries and spinach are just a few of the foods that are rich in vitamin C. Adult men should get at least 90 milligrams per day of vitamin C, while adult women should have at least 75 milligrams per day, according to the Institute of Medicine. The IOM also suggests an upper limit of 2,000 milligrams per day, lest people face the consequences listed above.
The IOM recommends that men and women get 11 milligrams and 8 milligrams, respectively, of zinc. It can be found in foods like oysters, red meat, poultry, beans, nuts and whole grains. Like vitamin C, consuming too much zinc exacts a toll on health; some nasal gels and sprays that contained zinc in caused anosmia (the inability to smell scents), and people who used too much denture cream containing zinc experienced copper deficiency and neurologic disease, notes the National Institutes for Health.
Most of us are not marathoners
Trials involving marathon runners, skiers and soldiers in sub-arctic environments found that these people were able to reduce their incidence of colds by 50 percent by taking anywhere from 250 milligrams to 1,000 milligrams per day of vitamin C, according to a 2007 Cochrane review of 30 placebo trials involving more than 11,000 total participants.
For everyone else, the results were a lot more modest. The review found that taking vitamin C preventively managed to reduce the length of a cold ― but not prevent it ― by eight percent for adults and 13.6 percent for children. That's statistically significant, but probably doesn't matter too much when a person is already in the throes of a cold. What's more, if participants started taking vitamin C after the cold had already started, the nutrient didn't have any effect on the symptoms or the length of the illness, concluded the National Institute of Health.
Research by the NIH also suggests that while levels of vitamin C rise in the body's tissues after a person takes doses of 250 to 500 milligrams, any amount above that causes the body's vitamin C levels to rise much more slowly ― at least in healthy young men.
Studies on zinc's ability to curtail colds or lessen their severity is more encouraging. A 2017 meta-analysis of seven randomized trials found that zinc lozenges shortened the length of the common cold by an average of 33 percent. Five of those trials gave participants a daily lozenge that had between 80 to 92 milligrams in it, which shortened colds by 33 percent. Two trials administered higher daily doses of zinc, at 192 to 207 milligrams, which lessened colds by 35 percent. Study author Harri Hemilia, of the University of Helsinki, concluded that people with common colds could try zinc lozenges to treat them, but said that more research needed to be done to figure out the best kind of lozenge, as well as the dose.
Where the supplements stand
Like all dietary supplements, Emergen-C and Airborne did not have to pass safety and efficacy research before hitting the market. That's not exactly heartening when you consider the tepid results of their active ingredients when it comes to cold prevention.
But the companies do seem to keep in mind the IOM's recommended upper limits for vitamin C. Emergen-C, which has 1,000 milligrams of vitamin C per serving, changed their recommended servings to align with medical opinion.
"The directions on our packages have been changed from two to four packets per day to one to two packets per day as we are simply being more conservative with our recommendations," a representative of Alacer Corp., Emergen-C's parent company, told HuffPost.
Airborne, an effervescent tablet meant to be dissolved in water, also has 1,000 milligrams of vitamin C per serving.
But unless researchers can conduct experiments specifically testing Emergen-C or Airborne's effectiveness, there's no way to tell for sure if they work, or why, according to Howard Sesso, an epidemiologist and associate professor of medicine at Brigham and Women's Hospital in Boston.
"It would be very difficult to know, even if it did work, is it because of Vitamin C, or is it because of Zinc?" said Sesso. "Is it because of something completely unrelated, or something that we don't yet know about?"
Here's what you should do instead
Sesso, a middle-aged man who eats well and exercises regularly, takes just one multivitamin a day. He says this option is probably appropriate for most people, as opposed to focusing on just one or two specific vitamins to avoid disease. While there certainly are special populations for which specific supplements are crucial — say, folic acid for pregnant women, to avoid birth defects — getting all your vitamins and minerals from a variety of healthy foods is the best way to approach nutritional health.
"Natural, food-based approach... is always more preferable," said Sesso.
Sesso also noted that there are certainly more effective ways to avoid illness during cold season. Some tactics include washing your hands frequently, staying away from sick people and keeping surfaces in your home clean.
UPDATE: Jan. 2, 2018 ―A previous version of this story cited a study on the ability of zinc supplementation to curtail colds or lessen their severity. The publishers of that study retracted it in April 2016 due to errors and allegations of plagiarism.
Healthy Living's Guide To Cold & Flu Season
We're here to help! Read on for tips on how to stay healthy among your wheezing coworkers, sniffling children and coughing fellow commuters:
There's No Good Reason Not To Get A Flu Vaccine Today
The Antibacterial Soap You DON'T Need
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But no matter what it is that drives someone to use their antipodal paw, science has also uncovered a particular set of personality traits that left-handed people tend to have. So for all of you lefties, leftie-loving righties, and ambidextrous folks out there -- it's time to brush up on your left-handed knowledge and help put an end to leftie discrimination once and for all.
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Lefties make up about 10 percent of the general population. But researchers have found that in populations with certain mental disorders, that rate goes up. Previous studies have found that people with psychosis had a 20 percent likelihood of being left-handed, though a small study in the journal SAGE found the rate of psychotic lefties may be even higher.
Researchers at Yale University in New Haven, Connecticut, and the University of Texas Southwestern Medical Center in Dallas assessed 107 patients at outpatient psychiatric clinics. For those with mood disorders such as depression or bipolar disorder, the rate of left-handedness was close to average, at 11 percent. But in people with psychosis, such as those with schizophrenia or schizoaffective disorder, the rate of left-handedness was 40 percent, well above average. Researchers theorize brain laterality plays a role.
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Scientists have also found an increased risk for dyslexia, ADHD, and certain mood disorders in left-handed people, according to a 2010 study published in Pediatrics. Researchers are not exactly sure how to explain this phenomenon, but many believe it's related to how the brain is wired. Your noggin is divided into two halves: the left side and the right side. Most people (righties and lefties alike) rely on the brain's left hemisphere for tasks like language functioning. But about 30 percent of left-handed folks are either partial to the right hemisphere or have no dominant hemisphere at all. According to scientists, having one hemisphere dominate is much more efficient, which is why some left-handers are at increased risk for learning impairments and brain disorders.
But lefties may be in luck when it comes to other health conditions: Results of a large survey published in the journal Laterality found that left-handers had lower rates of arthritis and ulcers.
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People who use their left hands when listening may more easily hear slowly-changing sounds than those who use their right hands, according to a study from Georgetown University Medical Center
The researchers who conducted the study, presented at Neuroscience 2012, found that the left and right hemispheres of the brain specialize in different kinds of sounds. The left hemisphere, which controls the right hand, likes rapidly-changing sounds like consonants, while the right hemisphere, which controls the left hand, likes slowly-changing sounds like syllables or intonation.
According to the researchers, if you're waving an American flag while listening to a presidential candidate, the speech will sound slightly different to you depending on whether you're holding the flag in your left or right hand. The research could ultimately result in better treatment for stroke and language disorders.
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Right-handed bias isn't just a modern-day phenomenon: It turns out we've been dominantly using our right hooks for more than 500,000 years.
University of Kansas researchers recently determined the handedness of ancient humans by studying -- oddly enough -- their teeth. The study, which was published in the journal Laterality, found that when our great-great-great-great-(you get the point)-grandfathers processed animal hides, they would hold one side of the carcass in one hand and the other in their mouth. By locating the wear and tear on those prehistoric chompers, scientists were able to determine whether our prehistoric ancestors were using their left hand or right hand more dominantly
\"All you need to have is a single tooth, and you can tell if our assumptions are right -- if the individual is right- or left-handed,\" study researcher David Frayer, Ph.D., told LiveScience. The results? \"The fossils are just like humans in that we are mostly right-handed, and so were they.\"
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Southpaws have been bragging about their creative clout for years. But is it true -- does being left-handed mean you're also more likely to be artistic or innovative?
According to research published in the American Journal of Psychology, there is some evidence that left-handed people have the upper hand in at least one creative facet: They're better at divergent thinking, a method of idea generation that explores many possible solutions.
To determine whether lefties were more likely to pursue creative careers than righties, the folks behind the Left-Handers Club (a pro-leftie group dedicated to left-handed research and product development) surveyed more than 2,000 left-handed, right-handed, and ambidextrous participants and found that lefties tended to find advantages and be drawn to careers in the arts, music, sports, and information-technology fields.
But that may also add up to lower paychecks: According to a report in the Wall Street Journal, left-handers' salaries are 10 percent lower on average than those of right-handers.
","credit":"Geri Lavrov via Getty Images","creditUrl":"","source":"","thumbnail":{"url":{"fileName":"55d3a1ff1700006e00567df5.jpeg","type":"hectorUrl"},"caption":"Young girl with painted hands and face","credit":"Geri Lavrov via Getty Images","width":5442,"height":3627},"title":"Lefties Make Better Artists","type":"image","meta":null,"summary":null,"badge":null,"textWrap":"noWrap"},"provider":null},{"embedData":{"type":"hector","url":"https://img.huffingtonpost.com/asset/55d3a31c1d00006e001452c4.jpeg","queryParams":{},"width":2941,"height":2075,"credit":"SAUL LOEB via Getty Images"},"type":"image","common":{"id":"55d3a31ce4b0ab468d9ecfc2","caption":"
It doesn't matter which way they swing politically: A surprisingly high percentage of recent U.S. presidents were on the left (in terms of handedness, of course).
The lengthy list of left-handed leaders includes four of the last seven commanders in chief -- President Obama, Bill Clinton, George H.W. Bush, and Gerald Ford -- as well as past presidents James Garfield and Harry Truman. In fact, there's a rumor that Ronald Reagan was born a leftie, but stringent schoolteachers converted him to a righty when he was young.
Should right-handed presidential wannabes fake it? Our penchant for left-handed POTUSes is probably pure coincidence. But one recent Dutch study suggests that left-handed politicians actually have an advantage in televised debates. As a whole, people tend to associate right-handed gestures with "good" and left-handed gestures with "bad," according to the researchers. Since television presents a mirror image, the lefties are the ones who appear to gesture with their right hands (the "good" hand).
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Golf legend Phil Mickelson, tennis ace Rafael Nadal, boxing champ Oscar de la Hoya -- did you know that a number of your favorite sports superstars are lefties?
Actually, left-handers may have the advantage in sports that involve two opponents facing each other, such as in tennis, boxing, and baseball, according to an MSNBC review of the book The Puzzle of Left-Handedness, by Rik Smits. The author chalks it up to the fact that left-handed athletes get a lot more opportunity to practice against right-handed opponents than vice versa (since there are so many more righties out there).
Now that's a home run for lefties.
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For the study, participants watched an eight-minute clip from the frightening film Silence of the Lambs. When asked to recall events from the segment, lefties were far more likely to show signs of post-traumatic stress disorder than righties, including giving fragmented descriptions and making more mistakes.
\"It seems that after experiencing a fearful event, even on film, people who are left-handed had subtle behaviors that were like people suffering from post-traumatic stress disorder,\" head researcher Carolyn Choudhary, PhD, told the Telegraph. Blame the brain: "It is apparent that the two sides of the brain have different roles in PTSD, and the right hand-side of the brain seems to be involved in fear. But we need to do more experiments to understand what exactly is going on here," she said.
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If you just can't let go of that spat you had with your right-handed pal (but he seemed to move on just fine), you may be able to blame it on your left-handedness. According to a small study published in the Journal of Nervous and Mental Disease, lefties are more prone to having negative emotions. In addition, they seem to have a more difficult time processing their feelings.
Again, this seems to be related to the brain-hand connection. Compared to righties, left-handed participants in the study showed an imbalance in activity between the left and right hemispheres when trying to process their moodiness.
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Aw-shucks. Lefties may get bent out of shape, but research shows they're just a bunch of bashful self-observers.
When scientists from Abertay University in Scotland gave 46 lefties and 66 rightiesbehavioral tests to measure their impulsiveness and personal restraint, the left-handers in the group more commonly agreed with statements like \"I worry about making mistakes\" and \"Criticism or scolding hurts me quite a bit.\" In fact, their answers left researchers believing that lefties tend to feel more inhibited, shy, and embarrassed than their right-handed counterparts.
\"Left-handers are more likely to hesitate, whereas right-handers tend to jump in a bit more,\" lead researcher Lynn Wright, PhD, told BBC News.
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Next time you have a run-in with a boozed-up barfly, check out which hand he's holding his whisky with: chances are, it'll be his left.
For years, myth has held that left-handers are more likely to become alcoholics. Research into the topic was murky, however, and relied on small samples. But a survey of more than 25,000 people from 12 countries has cleared things up a bit. While lefties are not more prone to alcoholism, they do drink more often.
Researcher Kevin Denny, who examined the data for a paper published in the British Journal of Health Psychology, says the main takeaway should be debunking that whole left-handedness-alcoholism link. "There is no evidence that handedness predicts risky drinking," he stated in a press release. "Hence, the results do not support the idea that excess drinking may be a consequence either of atypical lateralisation of the brain, or due to the social stresses that arise from left-handers' being a minority group."
","credit":"igorr1 via Getty Images","creditUrl":"","source":"","thumbnail":{"url":{"fileName":"55d3a58f1d00002f001452cd.jpeg","type":"hectorUrl"},"caption":"martin with lemon before a window in bar","credit":"igorr1 via Getty Images","width":3869,"height":2579},"title":"Lefties Like to Booze","type":"image","meta":null,"summary":null,"badge":null,"textWrap":"noWrap"},"provider":null},{"embedData":{"type":"hector","url":"https://img.huffingtonpost.com/asset/55d3a69f14000077002e348e.jpeg","queryParams":{},"width":3866,"height":2578,"credit":"Christopher Kimmel via Getty Images"},"type":"image","common":{"id":"55d3a69fe4b0ab468d9ed66f","caption":"
Mark your calendar: August 13 is International Left-Handers Day.
Lefties across the globe celebrate the annual event, which was launched in 1992 by the UK-based Left-Handers Club to increase awareness about the left-handed lifestyle. According to the group's Web site, it's a day "when left-handers everywhere can celebrate their sinistrality and increase public awareness of the advantages and disadvantages of being left-handed."
How should you observe the occasion? Create a "leftie zone": a designated area of personal space where everything must be done in a left-handed fashion, from your workspace setup to the way you use cutlery.
And that rule also extends to any right-handers who happen to enter the leftie zone.
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Left-handers are the minority. So does that mean they'll go extinct one day? In fact, some researchers believe that when it comes to survival of the fittest, lefties come out on top.
Here's why: In one-on-one combat, using the left-hand is like throwing a curveball. \"The fact that left-handers are less common means they have a surprise effect,\" University of Montpellier researcher Charlotte Faurie told ABC News. To dig deeper, Faurie and her colleague Michel Raymond studied nine different primitive societies. In more violent societies, they found, lefties thrived (think southpaw slugger Rocky Balboa's left hook).
Looks like the left hand has the upper hand after all.
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Vitamin C, also called ascorbic acid, is a water-soluble vitamin. Water-soluble vitamins are stored in the body in very limited amounts, and are excreted through the urine. Therefore, it is a good idea to have them in your daily diet. Vitamin C is sensitive to light, heat, and air and can be destroyed during food preparation, cooking, or storage. 
