The role of physical activity level and B-vitamin status on blood homocysteine levels.

Abstract

Exercise increases methionine metabolism, which also increases its amino acid metabolic intermediate, homocysteine (Hcy). High Hcy levels increase cardiovascular disease (CVD) risk, whereas B-vitamins (folate, vitamins B6, and B12) can reduce Hcy. Research exploring the relationship between exercise and Hcy is equivocal. To determine whether plasma Hcy values, independent of plasma B-vitamin concentrations, are higher in active (HighPA; > 420 min x wk(-1)) than less active (LowPA; < or = 420 min x wk(-1)) males (M = 38) and females (F = 38). Subjects were healthy, young (26 +/- 5 yr), used no B-vitamin supplements in last 30 d, and reported being physically active for the last 5 yr. Physical activity (PA) groups were based on moderate- to high-intensity PA (min x wk(-1)) using 7-d PA records. Dietary intakes of B-vitamins were assessed using 7-d weighed food records. The differences of Hcy between PA and gender were examined using ANCOVA, with plasma B-vitamins as covariates. Mean PA was 220 min x wk(-1) for LowPA (n = 36; VO2max = 42.8 +/- 8.8 mL x kg(-1) x min(-1)) and 652 min x wk(-1) for HighPA (n = 40; VO2max = 54.2 +/- 9.7 mL x kg(-1) x min(-1)). Hcy (micromol x L(-1)) was not different between PA levels (LowPA = 7.5 +/- 1.6; HighPA = 7.7 +/- 1.6, P = 0.36) or sex (M = 7.8 +/- 1.7; F = 7.4 +/- 1.1; P = 0.13). Plasma folate was the only significant covariate (P<0.001). However, secondary analysis revealed that Hcy levels were significantly higher in the most active and fit (ExHighPA; range = 758-1085 min x wk(-1); n = 11; > 90% VO2max) compared with the sedentary ones (ExLowPA; range = 9-130 min x wk(-1); n = 9; < 70% VO2max; 8.6 +/- 1.8 vs 6.7 +/- 1.5 micromol x L(-1); P = 0.007, respectively). Hcy, independent of plasma B-vitamin levels, was not different between PA levels in nonsupplementing young adults, unless PA was high (> 758 min x wk(-1)).