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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #152862
Title: PLASMA PYRIDOXAL 5'-PHOSPHATE CONCENTRATION IS CORRELATED WITH FUNCTIONAL VITAMIN B-6 INDICES IN PATIENTS WITH RHEUMATOID ARTHRITIS AND MARGINAL VITAMIN B-6 STATUS

Author
item CHIANG, EN-PEI - HNRCA
item BAGLEY, PAMELA - HNRCA
item ROUBENOFF, RONENN - HNRCA
item NADEAU, MARIE - HNRCA
item SELHUB, JACOB - HNRCA

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2003
Publication Date: 4/1/2003
Citation: CHIANG, E.I., BAGLEY, P.J., ROUBENOFF, R., NADEAU, M., SELHUB, J. PLASMA PYRIDOXAL 5'-PHOSPHATE CONCENTRATION IS CORRELATED WITH FUNCTIONAL VITAMIN B-6 INDICES IN PATIENTS WITH RHEUMATOID ARTHRITIS AND MARGINAL VITAMIN B-6 STATUS. JOURNAL OF NUTRITION. 2003;133:1056-59.

Interpretive Summary: In previous studies we and others have shown that patients with rheumatoid arthritis have a low level of vitamin B6 in their blood in spite of the fact that their dietary intake of this vitamin was adequate. In the present study we are showing that this low blood level of vitamin B6 is also a sign of many of the disease symptoms that afflict these patients. For example the lower the B6 in the blood the higher is the disability score, morning stiffness and degree of pain. We do not know at present what is the basis of this relationship and we know that taken vitamin B6 will not alleviate these symptoms. However it is quite possible that if we know the basis we can come up with a better treatment.

Technical Abstract: Many patients with rheumatoid arthritis (RA) have low plasma pyridoxal-phosphate (PLP) but a normal erythrocyte aspartate aminotransferase activity coefficient (alpha EAST), a measure of vitamin B-6 status in the erythrocytes, compared with healthy subjects. The goal of the present study was to examine the correlations of PLP levels in these two compartments (plasma and erythrocytes) with other established indices of vitamin B-6 status, and to determine which indicator better reflects functional status of vitamin B-6 in patients with RA. Multiple indices of vitamin B-6 status were measured in 33 patients with RA. Plasma PLP, urinary 4-pyridoxic acid (4-PA), net increase in plasma total homocysteine after a methionine load (DeltatHcy) and net increase in urinary xanthurenic acid after a tryptophan load (DeltaXA) were log-transformed to reach normality for statistical analyses. We found that log-plasma PLP levels were inversely correlated with both log-DeltatHcy (r=-0.368, P=0.035) and log-DeltaXA (r=-0.333, P=0.05). Plasma PLP was not correlated with alpha EAST or urinary 4-PA excretion. In contrast, erythrocyte PLP was inversely correlated with alpha EAST (r=0.431, P=0.012) and positively correlated with log-4-PA (r=0.475, P=0.005), but erythrocyte PLP was not correlated with the outcomes of a methionine or tryptophan load test. Erythrocyte PLP and log-4-PA, but not plasma PLP, were correlated with dietary intake of vitamin B-6 after adjusting for protein intake (r=0.420, P=0.015 and r=0.333, P=0.05, respectively). We suggest that in patients with RA, plasma PLP levels are a better diagnostic indicator of functional vitamin B-6 status than erythrocyte PLP levels.