![]() ![]() The richest sources of vitamin B6 include fish, beef liver and other organ meats, potatoes and other starchy vegetables, and fruit (other than citrus). Vitamin B6 is found in a wide variety of foods. * Adequate Intake (AI) Sources of Vitamin B6 Food Table 1: Recommended Dietary Allowances (RDAs) for Vitamin B6 Age For infants from birth to 12 months, the FNB established an AI for vitamin B6 that is equivalent to the mean intake of vitamin B6 in healthy, breastfed infants. Table 1 lists the current RDAs for vitamin B6. Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects.Estimated Average Requirement (EAR): Average daily level of intake estimated to meet the requirements of 50% of healthy individuals usually used to assess the nutrient intakes of groups of people and to plan nutritionally adequate diets for them can also be used to assess the nutrient intakes of individuals.Adequate Intake (AI): Intake at this level is assumed to ensure nutritional adequacy established when evidence is insufficient to develop an RDA.Recommended Dietary Allowance (RDA): Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals often used to plan nutritionally adequate diets for individuals.These values, which vary by age and gender, include: DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. Intake recommendations for vitamin B6 and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the FNB. However, the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences) used a plasma PLP level of 20 nmol/L as the major indicator of adequacy to calculate the Recommended Dietary Allowances (RDAs) for adults. PLP concentrations of more than 30 nmol/L have been traditional indicators of adequate vitamin B6 status in adults. Plasma PLP is the most common measure of vitamin B6 status. ![]() Vitamin B6 concentrations can also be measured indirectly by assessing either erythrocyte aminotransferase saturation by PLP or tryptophan metabolites. Vitamin B6 concentrations can be measured directly by assessing concentrations of PLP other vitamers or total vitamin B6 in plasma, erythrocytes, or urine. Phosphorylated forms of the vitamin are dephosphorylated, and the pool of free vitamin B6 is absorbed by passive diffusion. The human body absorbs vitamin B6 in the jejunum. Vitamin B6 is involved in gluconeogenesis and glycogenolysis, immune function (for example, it promotes lymphocyte and interleukin-2 production), and hemoglobin formation. ![]() Vitamin B6 also plays a role in cognitive development through the biosynthesis of neurotransmitters and in maintaining normal levels of homocysteine, an amino acid in the blood. Both PLP and PMP are involved in amino acid metabolism, and PLP is also involved in the metabolism of one-carbon units, carbohydrates, and lipids. Vitamin B6 in coenzyme forms performs a wide variety of functions in the body and is extremely versatile, with involvement in more than 100 enzyme reactions, mostly concerned with protein metabolism. ![]() Substantial proportions of the naturally occurring pyridoxine in fruits, vegetables, and grains exist in glycosylated forms that exhibit reduced bioavailability. Pyridoxal 5' phosphate (PLP) and pyridoxamine 5' phosphate (PMP) are the active coenzyme forms of vitamin B6. It is the generic name for six compounds (vitamers) with vitamin B6 activity: pyridoxine, an alcohol pyridoxal, an aldehyde and pyridoxamine, which contains an amino group and their respective 5'-phosphate esters. Vitamin B6 is a water-soluble vitamin that is naturally present in many foods, added to others, and available as a dietary supplement. For a reader-friendly overview of Vitamin B6, see our consumer fact sheet on Vitamin B6. This is a fact sheet intended for health professionals. Groups at Risk of Vitamin B6 Inadequacy. ![]()
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