Influence of dietary methionine with or without adequate dietary vitamins on hyperhomocysteinemia in rats

Information on the effects of dietary vitamins involved in homocysteine met abolism on the dietary methionine (Met)-induced hyperhomocysteinemia is lim ited. Thus, a six-wk study was conducted to investigate the effects of diet ary Met with or without adequate vitamins on plasma total homocysteine (tHc y) in rats. Four levels of supplemental L-Met (0, 5, 10 and 20 g/kg) and tw o levels of vitamins (adequate and deficient in folate plus B-12) were test ed in the casein-based diets. The plasma tHcy values in males were higher ( p < 0.05) than in females (8.1+/-0.6 vs. 6.0+/-0.6 <mu>mol/L for adequate d iet; 66.5+/-1.4 vs. 45.5+/-0.9 mu mol/L for folate-B-12 deficient diet). In males, supplementation of the adequate (control) diet with 5, 10 and 20 g/ kg Met, increased tHcy to 1.3, 1.9 and 7.9 times control, respectively. In females, the corresponding values were 1.3, 1.7 and 5.6 times control. In r ats fed folate-B-12 deficient diets, supplemental Met, however, generally c aused reductions in plasma tHcy values in both sexes. These disparate respo nses to supplementary Met could be partly due to increases in hepatic S-ade nosylmethionine (SAM)/S-adenosylhomocysteine (SAH) ratios in folate-B-12 de ficient rats. (C) 2000 Elsevier Science Inc.