Assessment of Vitamin B-6 Status in Young Women Consuming a Controlled Diet Containing Four Levels of Vitamin B-6 Provides an Estimated Average Requirement and Recommended Dietary Allowance

• Published in: The Journal of nutrition Vol. 131; no. 6; pp. 1777 - 1786
• Main Authors: Hansen, Christine M., Shultz, Terry D., Memon, H. Sara, Kwak, Ho-Kyung, Leklem, James E.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.06.2001; American Society for Nutritional Sciences
• Subjects: Administration, Oral; Adult; alanine transaminase; Alanine Transaminase - analysis; Aspartate Aminotransferases - analysis; aspartate transaminase; Biological and medical sciences; blood plasma; Body Mass Index; diet; Diet - standards; enzyme activity; erythrocytes; Erythrocytes - metabolism; Estimated Average Requirement; Ethnic Groups; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Humans; metabolites; nutrient content; nutrient requirements; Nutrition Policy; Nutritional Status; prediction; Pyridoxal Phosphate - blood; Pyridoxal Phosphate - urine; Pyridoxamine - analogs & derivatives; Pyridoxamine - blood; Pyridoxamine - urine; Pyridoxic Acid - blood; Pyridoxic Acid - urine; pyridoxine; Pyridoxine - administration & dosage; Pyridoxine - blood; Pyridoxine - urine; Recommended Dietary Allowance; status assessment; urine; Vertebrates: anatomy and physiology, studies on body, several organs or systems; vitamin B-6; women; young adults; Estimated Average Requirement; EALT; PNG; RDA; vitamin B-6; status assessment; 4-PA; PMP; PLP; EAR; DRI; PL; EAST; Recommended Dietary Allowance; PN; women; Human; Micronutrient; Nutrient requirement; Dietary allowance; Diet; Estimation; Young adult; Female; B-Vitamins; Pyridoxine; Nutritional status; Feeding
• ISSN: 0022-3166; 1541-6100
• DOI: 10.1093/jn/131.6.1777

The Recommended Dietary Allowance (RDA) of vitamin B-6 for young women was recently reduced from 1.6 to 1.3 mg/d based on an adequate plasma pyridoxal phosphate (PLP) concentration of 20 nmol/L. To assess vitamin B-6 requirements and suggest recommendations for intake, seven healthy young women consumed a controlled diet providing 1.2 g protein/kg body weight for a 7-d adjustment period (1.0 mg vitamin B-6/d) and three successive 14-d experimental periods (1.5, 2.1 and 2.7 mg/d, respectively). Direct and indirect vitamin B-6 status indicators were measured in plasma, erythrocytes and urine. Indicators most strongly correlated with vitamin B-6 intake [i.e., plasma and erythrocyte PLP, urinary 4-pyridoxic acid (4-PA) and total vitamin B-6] were regressed on vitamin B-6 intake and the dietary vitamin B-6 to protein ratio. Inverse prediction using adequate and baseline values estimated vitamin B-6 requirement. Adequate values were determined for plasma PLP and urinary 4-PA from baseline values of 60 previous subjects, using the statistical method suggested by Sauberlich. The current study suggests a vitamin B-6 Estimated Average Requirement (EAR) for young women of 1.1 mg/d or 0.016 mg/g protein, and a RDA of 1.5 mg/d or 0.020 mg/g protein. When results from this study are combined with data from four other recent studies, the combined data predict an EAR of 1.2 mg/d or 0.015 mg/g protein, and a RDA of 1.7 mg/d or 0.018 mg/g protein. This study suggests that the current vitamin B-6 RDA may not be adequate.