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1.
Vitamin B12, B6, or Folate and Cognitive Function in Community-Dwelling Older Adults: A Systematic Review and Meta-Analysis.
Zhang, C, Luo, J, Yuan, C, Ding, D
Journal of Alzheimer's disease : JAD. 2020;(2):781-794
Abstract
BACKGROUND Previous studies have indicated that B vitamin deficiencies are an essential cause of neurological pathology. There is a need to provide evidence of the benefit of B vitamins for the prevention of cognitive decline in community-dwelling older adults. OBJECTIVE To examine the association between intake and plasma levels of vitamins B12, B6, and folate and cognitive function in older populations through a systematic review and meta-analysis. METHODS Medline (PubMed), EMBASE, and Cochrane databases were used to search the literature though August 8, 2019. We included observational population-based studies evaluating the association between concentrations or intake levels of vitamins B6, B12, or folate and cognition in older adults aged ≥45 years. The quality of all studies was assessed by the modified Newcastle-Ottawa Scale. Odds ratios (ORs) and hazard ratios (HRs) were analyzed by the random-effects model. Sensitivity analyses were conducted by excluding the studies with significant heterogeneity. RESULTS Twenty-one observational studies with sample sizes ranging from 155-7030 were included in the meta-analysis. Higher levels of vitamin B12 (OR = 0.77, 95% CI = 0.61-0.97) and folate concentration (OR = 0.68, 95% CI = 0.51-0.90) were associated with better cognition in cross-sectional studies, but not in sensitivity analyses or prospective studies. High vitamin B6 concentrations showed no significant benefit on cognition and dementia risk. Prospective studies did not provide substantial evidence for the relationship. CONCLUSION The results from our meta-analysis suggest that vitamins B12, B6, and folate may not be modifiable risk factors for slowing cognitive decline among community-dwelling older individuals.
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2.
Association Between One-carbon Metabolism-related Vitamins and Risk of Breast Cancer: A Systematic Review and Meta-analysis of Prospective Studies.
Zeng, J, Gu, Y, Fu, H, Liu, C, Zou, Y, Chang, H
Clinical breast cancer. 2020;(4):e469-e480
Abstract
Epidemiologic studies focusing on the association between 1-carbon metabolism-related vitamins (ie, folate, vitamin B6, vitamin B2, vitamin B12) and breast cancer risk have reported inconsistent findings. We conducted a systematic search of the reported data and performed a meta-analysis of prospective case-control and cohort studies to derive a more precise evaluation. The PubMed and EMBASE databases were searched to identify eligible studies. A total of 27 studies involving 49,707 cases and 1,274,060 individuals were included in the meta-analysis. The results indicated that a high intake of folate, vitamin B6, and vitamin B2 might decrease the risk of breast cancer. The corresponding pooled relative risks (RRs) for the highest intake compared with the lowest were 0.93 (95% confidence interval [CI], 0.88-0.99; P = .018), 0.94 (95% CI, 0.89-1.00; P = .037) and 0.90 (95% CI, 0.82-0.99; P = .026). No significant association between vitamin B12 and breast cancer risk was found (RR, 0.99; 95% CI, 0.94-1.04; P = .604). Further study showed that folate and vitamin B6 might decrease the risk of estrogen receptor-negative (ER-)/progesterone receptor-negative (PR-) breast cancer but not ER+/PR+ breast cancer. The dose-response meta-analysis indicated a significant linearity relationship between folate intake and a reduced risk of ER-/PR- breast cancer. An increment of folate intake (100 μg/d) corresponded to a 7% deceased risk of ER-/PR- breast cancer (RR, 0.93; 95% CI, 0.89-0.98; P = .007). In conclusion, a high intake of 1-carbon metabolism-related vitamins might contribute to the prevention of breast cancer, especially ER-/PR- breast cancer.
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3.
Intake of vitamin B6, folate, and vitamin B12 and risk of coronary heart disease: a systematic review and dose-response meta-analysis of prospective cohort studies.
Jayedi, A, Zargar, MS
Critical reviews in food science and nutrition. 2019;(16):2697-2707
Abstract
The objective of this study was to quantify the association of B-vitamins intake with the future risk of coronary heart disease (CHD). A systematic search was performed with the use of PubMed and Scopus from inception to April 30, 2018. Prospective cohort studies evaluating the association of intake of folate, vitamin B6, and vitamin B12 with risk of CHD in the general population were included. A random-effects meta-analysis was performed. Eleven prospective cohort studies (total n = 369,746) with 5133 cases of CHD were included in the analyses. The relative risks were: 0.79 (95%CI: 0.69, 0.89; I2 = 67%) for a 250 µg/d increment in folate intake; 0.87 (95%CI: 0.78, 0.96; I2 = 80%) for a 0.5 mg/d increment in vitamin B6 intake; and 0.97 (95%CI: 0.80, 1.14: I2 = 67%) for a 3 µg/d increment in vitamin B12 intake. The results did not change materially when the analyses were restricted only to dietary vitamins intake. A nonlinear dose-response meta-analysis demonstrated a linear inverse association between folate and vitamin B6 intake and risk of CHD. In conclusion, higher intake of folate and vitamin B6 is associated with a lower risk of CHD in the general population.
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4.
Vitamin B6 Intake and Pancreatic Carcinoma Risk: A Meta-Analysis.
Peng, YF, Han, MM, Huang, R, Dong, BB, Li, L
Nutrition and cancer. 2019;(7):1061-1066
Abstract
Objectives: There are conflicting results for the association between vitamin B6 intake with reduced pancreatic carcinoma risk. Thus, a meta-analysis was performed to summarize the evidences from epidemiological studies. Methods: We searched documents from PubMed-Medline, Web of Science, and Cochrane Library. The results were analyzed by using Stata software. Results: A total of nine studies were included. The multivariate-adjusted results found that the total RR values of pancreatic carcinoma was 0.65 (95% CI: 0.53-0.80) for the highest vitamin B6 intake vs the lowest vitamin B6 intake, and there was no significant heterogeneity among studies (I2 = 42.0%, P = 0.087). Sensitivity analysis indicated that no single study leaded to an excessive change for the relation between vitamin B6 intake and pancreatic carcinoma risk. Conclusions: This meta-analysis suggested that vitamin B6 intake could significantly decrease pancreatic carcinoma risk. However, further study is needed based on the limitations of the current analysis.
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5.
Vitamin B6 and Cancer Risk: A Field Synopsis and Meta-Analysis.
Mocellin, S, Briarava, M, Pilati, P
Journal of the National Cancer Institute. 2017;(3):1-9
Abstract
BACKGROUND Vitamin B6 is involved in many biochemical reactions and might play a role in carcinogenesis. We summarized the evidence linking vitamin B6 to cancer risk. METHODS We conducted a systematic review of both observational and intervention studies investigating the relationship between vitamin B6 intake or blood levels of its bioactive form pyridoxal-5'-phosphate (PLP) and the risk of any type of cancer. Random-effects meta-analysis was used to calculate pooled relative risks (RRs) and their 95% confidence intervals (CIs) across studies for high vs low categories of vitamin intake or PLP levels. We also performed a random-effects dose-response meta-analysis. RESULTS We identified 121 observational studies (participants, n = 1 924 506; cases, n = 96 , 436) and nine randomized controlled trials (RCTs; participants, n = 34 911; cases, n = 2539) considering 19 tumor sites. High intake of dietary (food only) vitamin B6 was statistically significantly associated with lower risk of all cancers (relative risk [RR] = 0.78, 95% CI = 0.73 to 0.84) and specific tumors, with special regard to gastrointestinal carcinomas (RR = 0.68, 95% CI = 0.61 to 0.75). An inverse association was also observed between high PLP levels and the risk of all cancers (RR = 0.66, 95% CI = 0.58 to 0.76) and single tumor sites, the most consistent results being those for gastrointestinal tumors (RR = 0.56, 95% CI = 0.48 to 0.65). There was a statistically significant inverse linear relationship between cancer risk and both vitamin B6 dietary intake and PLP levels. When total (food and supplements) intake was considered, the associations were weaker or null. Findings from RCTs did not support a protective effect of vitamin B6 against cancer, although this evidence was graded as low level. CONCLUSIONS Epidemiological evidence supports the potential of vitamin B6 as a cancer risk reduction agent and the role of PLP as a cancer screening biomarker, especially for gastrointestinal tumors. However, inconsistent findings from total intake and intervention studies suggest that vitamin B6 might also be an indicator of other dietary protective micronutrients.
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[A Systematic Review to Identify Unacceptable Intake Levels of Vitamin B6 among Patients Taking Levodopa].
Sato, Y, Yasumiishi, C, Chiba, T, Umegaki, K
Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan. 2017;(6):268-274
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Abstract
The interaction of levodopa and vitamin B6 is a well-known issue. This study investigated the incidence of unacceptable intake levels of vitamin B6 among levodopa users by means of a systematic review. We searched two databases (PubMed and "Igaku Chuo Zasshi") for articles about adverse events due to the interaction of levodopa and vitamin B6 published up to August 2017. Of 98 citations retrieved, 11 studies met the selection criteria. The results indicated that a vitamin B6 intake level of more than 50 mg/day could reduce the efficacy of levodopa. The recommended intake of vitamin B6 for Japanese adults is 1.4 mg/day for men and 1.2 mg/day for women. Therefore, the acceptable intake of vitamin B6 for levodopa patients would be within the range of the recommended intake level, which is also within the usual range in foods in Japan, except for dietary supplements or health foods. Levodopa users should be cautious about taking dietary supplements and over-the-counter drugs.
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Plasma Homocysteine, Serum Folic Acid, Serum Vitamin B12, Serum Vitamin B6, MTHFR, and Risk of Normal-Tension Glaucoma.
Li, J, Xu, F, Zeng, R, Gong, H, Lan, Y
Journal of glaucoma. 2016;(2):e94-8
Abstract
BACKGROUND This meta-analysis aims to comprehensively evaluate the association between total homocysteine (tHcy) levels, serum folic acid, vitamin B12, vitamin B6 levels, methylenetetrahydrofolate reductase (MTHFR) C677T genotype, and risk of normal-tension glaucoma (NTG). MATERIALS AND METHODS A systematic search of the EMBASE and PubMed databases was performed to evaluate plasma tHcy levels, serum folic acid, B vitamins' mean difference, and odds ratios of MTHFR C677T genotype between cases and controls. RESULTS A total of 7 studies including 458 cases and 555 controls meeting the inclusion criteria were involved in this meta-analysis. There were 4 studies for tHcy (149 cases and 148 controls), 2 studies for vitamin B6, vitamin B12, and folate (90 cases and 82 controls), and 4 studies for MTHFR (343 cases and 449 controls). Overall, the mean plasma tHcy levels, serum folic acids, vitamin B12, and vitamin B6 levels were 1.16 μmol/L [95% confidence interval (CI), -0.13, 2.45], -0.62 μmol/L (95% CI, -1.98, 0.74), 5.81 μmol/L (95% CI, -3.53, 15.14), and -16.79 μmol/L (95% CI, -86.09, 52.51). MTHFR TT genotype was found to be unrelated to NTG risk (odds ratio=1.08; 95% CI, 0.69, 1.69). CONCLUSION NTG is not associated with elevated plasma tHcy, serum folic acid, serum vitamin B12, serum vitamin B6, and MTHFR C677T genotype.
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[Meta-analysis on effect of combined supplementation of folic acid, vitamin B12 and B6 on risk of cardio-cerebrovascular diseases in randomized control trials].
Lan, X, Dang, SN, Zhao, YL, Yan, H, Yan, H
Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi. 2016;(7):1028-34
Abstract
OBJECTIVE To evaluate the effect of the combined supplementation of folic acid, vitamin B12 and B6 on the risk of cardio-cerebrovascular diseases. METHODS The literatures of randomized control trials about the relationship between the combined supplementation of folic acid, vitamin B12 and B6 and risk of cardio-cerebrovascular diseases from 1980 to 2014 were retrieved, and the eligible studies were screened for a Meta-analysis. The study indicators were the incidences of cardiovascular disease events, myocardial infarction and stroke. The cffect indicators were relative risk(RR)and 95% confidence interval(CI). Jadad score was used for the quality evaluation of the trials used in the study. RESULTS The literatures of 11 randomized control trials, involving 26 395 patients, were used in the Meta-analysis. The combined supplementation of B vitamins had no effect on the incidence of cardiovascular disease events(RR=1.00, 95% CI: 0.94-1.07)based on 8 studies. The combined supplementation of B vitamins had no effect on the incidence of myocardial infarction(RR= 1.03, 95% CI: 0.94-1.13)based on 9 studies. The combined supplementation of B vitamins could reduce the incidence of stroke by 14%(RR=0.86, 95%CI: 0.78-0.95)based on 9 studies. Compared with the control group, Taking folic acid combined with vitamin B12 and B6 could reduce the level of homocysteine by 2.53 μmol/L(95%CI:-3.93--1.12). Subgroup analysis indicated that the follow-up time, the dosage of folic acid and vitamin B12 and B6, the history of diseases had no confounding effect on the incidence of cardio-cerebrovascular disease events. But the subgroup analysis for stroke showed that with the extension of follow-up time, the supplementation of B vitamins could reduce the risk of stroke. The effect of folic acid and B12 in small dosage seemed more significant in the prevention of stroke, while the preventive effect of B6 increased with increasing dosage. The preventive effect of combined supplementation of B vitamins was more significant for the patients with a history of cardio-cerebrovascular diseases. CONCLUSION Taking folic acid combined with vitamin B6 and B12 might have no significant effect on the incidences of cardio-cerebrovascular disease events and myocardial infarction, but could lower the risk of stroke and the level of homocysteine.
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Effect of B vitamin (folate, B6, and B12) supplementation on osteoporotic fracture and bone turnover markers: a meta-analysis.
Ruan, J, Gong, X, Kong, J, Wang, H, Zheng, X, Chen, T
Medical science monitor : international medical journal of experimental and clinical research. 2015;:875-81
Abstract
BACKGROUND B vitamins (including folate, B6, and B12) supplementation can effectively and easily modify high plasma homocysteine (Hcy). However, the role of Hcy in the pathogenesis of osteoporotic fracture and bone turnover is still controversial. This meta-analysis aimed to assess the impact of B vitamin supplementation on occurrence of any osteoporotic fracture and bone turnover by pooling the results of previous studies. MATERIAL AND METHODS Relevant randomized controlled trials (RCTs) were searched in databases. Data integration and analysis were done by using Review Manager 5.3 (the Cochrane Collaboration). The risk ratio (RR) and corresponding 95% confidence intervals (CI) of fracture (intervention vs. control) were estimated. Changes in bone turnover indicators (continuous data), weighted mean difference (WMD), and corresponding 95% (CI) were pooled for estimation. RESULTS Based on the results of 4 RCTs, this meta-analysis failed to identify a risk-reducing effect of daily supplementation of B vitamins on osteoporotic fracture in patients with vascular disease and with relatively normal plasma Hcy. In addition, we also did not find any positive effects of B vitamin supplementation on bone turnover. CONCLUSIONS B vitamin supplementation might not be effective in preventing fracture and improving bone turnover. However, the possible benefits in selective populations, such as populations with very high plasma Hcy and from regions without B vitamin fortification should be explored in the future.
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Vitamin B2 intake and the risk of colorectal cancer: a meta-analysis of observational studies.
Liu, Y, Yu, QY, Zhu, ZL, Tang, PY, Li, K
Asian Pacific journal of cancer prevention : APJCP. 2015;(3):909-13
Abstract
BACKGROUND A systematic review and meta-analysis of observational studies evaluated the association of intake of vitamin B2 with the incidence of colorectal cancer. MATERIALS AND METHODS Relevant studies were identified in MEDLINE via PubMed (published up to April 2014). We extracted data from articles on vitamin B2 and used multivariable-adjusted odds ratio (OR) and a random-effects model for analysis. RESULTS We found 8 articles meeting the inclusion criteria (4 of cohort studies and 4 of case-control studies) and a total of 7,750 colorectal cancer cases were included in this meta-analysis. The multivariable-adjusted OR for pooled studies for the association of the highest versus lowest vitamin B2 intake and the risk of colorectal cancer was 0.83 (95% confidence interval [95%CI]:0.75,0.91). We performed a sensitivity analysis for vitamin B2. If we omitted the study by Vecchia et al., the pooled OR was 0.86 (95%CI, 0.77,0.96). CONCLUSIONS This is the first meta-analysis to study links between vitamin B2 and colorectal cancer. We found vitamin B2 intake was inversely associated with risk of colorectal cancer. However, further research and large sample studies need to be conducted to better validate the result.