Plasma Pyridoxal 5'-phosphate (PLP) in the United States population: the National Health and Nutrition Examination Survey, 2003-2004

Authors: MORRIS, MARTHA - HNRCA AT TUFTS UNIVERSITY; PICCIANO, MARY - NIH OFFICE OF DIET SUPP.; Jacques, Paul; Selhub, Jacob

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2007
Publication Date: 5/1/2008
Citation: Morris, M.S., Picciano, M.F., Jacques, P., Selhub, J. 2008. Plasma Pyridoxal 5'-phosphate (PLP) in the United States population: the National Health and Nutrition Examination Survey, 2003-2004. American Journal of Clinical Nutrition. 87(5):1446-1454.

Interpretive Summary: No large-scale, population-based study has considered the descriptive epidemiology of vitamin B6 status using the biological marker, plasma pyridoxal 5’ - phosphate (PLP). Consequently, how vitamin B6 status varies with basic demographic and lifestyle factors is unclear. We sought to examine the epidemiology of vitamin B6 status in the US population. In >6,000 participants aged >/= 1 year in the U S National Health and Nutrition Examination Survey (2003-2004), we considered relationships between plasma PLP and various subject characteristics and examined trends in plasma PLP and homocysteine with vitamin B6 intake -- both overall and in selected subgroups. In males, plasma PLP decreased with age after adolescence in non-users of supplemental vitamin B6 only. Regardless of supplement use, plasma PLP concentrations of women of childbearing age were significantly lower than those of comparably aged men, and most oral contraceptive (OC) users had plasma PLP<20 nmol/L. The prevalence of low plasma PLP was significantly >3% at vitamin B6 intakes from 2-2.9 mg/d in all subgroups, and at intakes from 3-4.9 mg/d in smokers, the elderly, non-Hispanic blacks, and current and former OC users. Intakes from 3-4.9 mg/d versus <2 mg/d were associated with significant protection from low plasma PLP in most subgroups, and from hyperhomocysteinemia in the elderly. Vitamin B6 intakes of 3-4.9 mg/d appear consistent with the definition of an RDA for most Americans. However, at that intake level, substantial proportions of some population subgroups may not meet accepted criteria for adequate vitamin B6 status.

Technical Abstract: No large-scale, population-based study has considered the descriptive epidemiology of vitamin B6 status using the biological marker, plasma pyridoxal 5’ - phosphate (PLP). Consequently, how vitamin B6 status varies with basic demographic and lifestyle factors is unclear. We sought to examine the epidemiology of vitamin B6 status in the US population. In >6,000 participants aged >/= 1 year in the U S National Health and Nutrition Examination Survey (2003-2004), we considered relationships between plasma PLP and various subject characteristics and examined trends in plasma PLP and homocysteine with vitamin B6 intake -- both overall and in selected subgroups. In males, plasma PLP decreased with age after adolescence in non-users of supplemental vitamin B6 only. Regardless of supplement use, plasma PLP concentrations of women of childbearing age were significantly lower than those of comparably aged men, and most oral contraceptive (OC) users had plasma PLP<20 nmol/L. The prevalence of low plasma PLP was significantly >3% at vitamin B6 intakes from 2-2.9 mg/d in all subgroups, and at intakes from 3-4.9 mg/d in smokers, the elderly, non-Hispanic blacks, and current and former OC users. Intakes from 3-4.9 mg/d versus <2 mg/d were associated with significant protection from low plasma PLP in most subgroups, and from hyperhomocysteinemia in the elderly. Vitamin B6 intakes of 3-4.9 mg/d appear consistent with the definition of an RDA for most Americans. However, at that intake level, substantial proportions of some population subgroups may not meet accepted criteria for adequate vitamin B6 status.