B vitamins

About: B vitamins is a research topic. Over the lifetime, 7433 publications have been published within this topic receiving 272929 citations. The topic is also known as: B vitamin & vitamin B complex.

Dietary reference intakes: vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc.

Abstract: Dietary Reference Intakes (DRIs) represent the new approach adopted by the Food and Nutrition Board to providing quantitative estimates of nutrient intakes for use in a variety of settings, replacing and expanding on the past 50 years of periodic updates and revisions of the Recommended Dietary Allowances (RDAs). The DRI activity is a comprehensive effort undertaken to include current concepts about the role of nutrients and food components in long-term health, going beyond deficiency diseases. The DRIs consist of 4 reference intakes: the RDA, which is to be used as a goal for the individual; the Tolerable Upper Intake Level (UL), which is given to assist in advising individuals what levels of intake may result in adverse effects if habitually exceeded; the Estimated Average Requirement (EAR), the intake level at which the data indicate that the needs for 50% of those consuming it will not be met; and the Adequate Intake (AI), a level judged by the experts developing the reference intakes to meet the needs of all individuals in a group, but which is based on much less data and substantially more judgment than that used in establishing an EAR and subsequently the RDA. When an RDA cannot be set, an AI is given. Both are to be used as goals for an individual. Two reports have been issued providing DRIs for nutrients and food components reviewed to date: these include calcium and its related nutrients: phosphorus, magnesium, vitamin D, and fluoride; and most recently, folate, the B vitamins, and choline. The approaches used to determine the DRIs, the reference values themselves, and the plans for future nutrients and food components are discussed. J Am Diet Assoc. 1998;98: 699–706 .

A quantitative assessment of plasma homocysteine as a risk factor for vascular disease. Probable benefits of increasing folic acid intakes

Abstract: Objective. —To determine the risk of elevated total homocysteine (tHcy) levels for arteriosclerotic vascular disease, estimate the reduction of tHcy by folic acid, and calculate the potential reduction of coronary artery disease (CAD) mortality by increasing folic acid intake. Data Sources. —MEDLINE search for meta-analysis of 27 studies relating homocysteine to arteriosclerotic vascular disease and 11 studies of folic acid effects on tHcy levels. Study Selection and Data Extraction. —Studies dealing with CAD, cerebrovascular disease, and peripheral arterial vascular disease were selected. Three prospective and six population-based case-control studies were considered of high quality. Five cross-sectional and 13 other case-control studies were also included. Causality of tHcy's role in the pathogenesis of vascular disease was inferred because of consistency across studies by different investigators using different methods in different populations. Data Synthesis. —Elevations in tHcy were considered an independent graded risk factor for arteriosclerotic vascular diseases. The odds ratio (OR) for CAD of a 5-μmol/L tHcy increment is 1.6(95% confidence interval [Cl], 1.4 to 1.7) for men and 1.8 (95% Cl, 1.3 to 1.9) for women. A total of 10% of the population's CAD risk appears attributable to tHcy. The OR for cerebrovascular disease (5-μmol/L tHcy increment) is 1.5 (95% Cl, 1.3 to 1.9). Peripheral arterial disease also showed a strong association. Increased folic acid intake (approximately 200 μg/d) reduces tHcy levels by approximately 4 μmol/L. Assuming that lower tHcy levels decrease CAD mortality, we calculated the effect of (1) increased dietary folate, (2) supplementation by tablets, and (3) grain fortification. Under different assumptions, 13 500 to 50 000 CAD deaths annually could be avoided; fortification of food had the largest impact. Conclusions. —A 5-μmol/L tHcy increment elevates CAD risk by as much as cholesterol increases of 0.5 mmol/L (20 mg/dL). Higher folic acid intake by reducing tHcy levels promises to prevent arteriosclerotic vascular disease. Clinical trials are urgently needed. Concerns about masking cobalamin deficiency by folic acid could be lessened by adding 1 mg of cobalamin to folic acid supplements. ( JAMA . 1995;274:1049-1057)

Vitamin Status and Intake as Primary Determinants of Homocysteinemia in an Elderly Population

Abstract: Objective. —To describe the distribution of plasma homocysteine concentrations in an elderly population and to analyze the relationship between homocysteine level and intake of vitamins and serum levels of vitamins that serve as coenzymes in homocysteine metabolism. Design. —Cross-sectional analysis of homocysteine levels and vitamin blood levels and intake in elderly participants in the Framingham Study. Setting. —Population-based cohort in Framingham, Mass. Participants. —A total of 1160 adult survivors, aged 67 to 96 years, from the original Framingham Heart Study cohort. Main Outcome Measures. —Plasma homocysteine concentration correlated with plasma folate, vitamin B 12 , pyridoxal-5'-phosphate (PLP), and oral intakes of these vitamins, and the contribution of these vitamins to the prevalence of elevated homocysteine in the population. Results. —Homocysteine levels were positively correlated with age after controlling for vitamin concentrations. After controlling for age, sex, and levels of other vitamins, homocysteine exhibited a strong inverse association with plasma folate. When subjects were grouped by deciles of plasma folate, mean homocysteine was significantly higher in the lowest two folate deciles (15.6 and 13.7 μmol/L, respectively) than in the highest decile (11.0 μmol/L). Homocysteine demonstrated weaker, inverse associations with plasma vitamin B 12 and PLP. Similar inverse associations were demonstrated between homocysteine and intakes of folate and vitamin B 6 , but not vitamin B 12 . Prevalence of high homocysteine (>14 μmol/L) was 29.3% in this cohort, and was greatest among subjects with low folate status. Inadequate plasma concentrations of one or more B vitamins appear to contribute to 67% of the cases of high homocysteine. Conclusions. —These results indicate a strong association between homocysteine concentration and folate, vitamin B 12 , and vitamin B 6 status, as well as age. It is possible that a substantial majority of the cases of high homocysteine in this older population can be attributed to vitamin status. ( JAMA . 1993;270:2693-2698)

Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline

Abstract: This report is the second in a series that presents a comprehensive set of reference values for nutrient intakes for healthy U.S and Canadian populations. It is a product of the Food and Nutrition Board of the Institute of Medicine (IOM) working in cooperation with scientists from Canada.The report establishes a set of reference values for the B vitamins and choline to replace previously published Recommended Dietary Allowances (RDAs) for the United States and Recommended Nutrient Intakes (RNIs) for Canada. It considers evidence concerning the prevention of disease and developmental disorders along with more traditional evidence of sufficient nutrient intake; and examines data about choline, a food component that in the past has not been considered essential in the human diet. Although the reference values are based on data, the data were often scanty or drawn from studies that had limitations in addressing the question. Thus, scientific judgment was required in setting the reference values. The reasoning used is described for each nutrient in Chapters 4 through 12. Evidence concerning the use of these nutrients for the amelioration or cure of disease or disability was not considered because that was beyond the project's scope of work.

Homocysteine Lowering with Folic Acid and B Vitamins in Vascular Disease

Abstract: risk, 0.95; 95 percent confidence interval, 0.84 to 1.07; P = 0.41). As compared with placebo, active treatment did not significantly decrease the risk of death from cardiovascular causes (relative risk, 0.96; 95 percent confidence interval, 0.81 to 1.13), myocardial infarction (relative risk, 0.98; 95 percent confidence interval, 0.85 to 1.14), or any of the secondary outcomes. Fewer patients assigned to active treatment than to placebo had a stroke (relative risk, 0.75; 95 percent confidence interval, 0.59 to 0.97). More patients in the active-treatment group were hospitalized for unstable angina (relative risk, 1.24; 95 percent confidence interval, 1.04 to 1.49). Conclusions Supplements combining folic acid and vitamins B 6 and B 12 did not reduce the risk of major cardiovascular events in patients with vascular disease. (ClinicalTrials.gov number, NCT00106886; Current Controlled Trials number, ISRCTN14017017.)