[Nutritional determinants of homocysteinemia]

Vitamin B12, folate and vitamin B6 are the main determinants of homocysteinemia. These B-group vitamins influence two metabolic pathways of homocysteine reduction, which prevail in dependence to methionine intake. Transsulfuration (vitamin B6) dominates under condition of overnutrition with prevalence of animal food sources, remethylation (vitamin B12 and folic acid) is decisive under conditions of malnutrition, alternative nutrition or optimal traditional diet.

Plasma homocysteine and folic acid, vitamins B12 and B6 in serum were measured in alternative nutrition groups of adults (vegans, vegetarians (lacto + lactoovo), semivegetarians, n = 39) and compared with those values in group consuming traditional diet--control group, general population (n = 35). In alternative nutrition groups, the average homocysteine level is significantly higher (vegans 17.2 mumol/l, vegetarians 12.9 mumol/l, semivegetarians 10.1 mumol/l, control group 9.9 mumol/l); the frequency of hyperhomocysteinemia (over 15 mumol/l) is 50%, 32%, 14% vs. 6% in control group. Vegetarians and vegans have a significantly higher levels of vitamin B6 and folic acid; the frequency of vitamin B6 deficit is 60% and 57% in control group and semivegetarian group vs. 16% and 0% in vegetarian and vegan group. Folate deficit was found in 16% of traditional group vs. 0% in alternative groups. Serum levels of vitamin B12 are significantly reduced in subjects consuming alternative nutrition with deficiency observed in 67% of vegans, 32% of vegetarians, 14% of semivegetarians vs. 0% in control group.

Vitamin levels in relation to nutritional regime and metabolic pathways of homocysteine show that the mild hyperhomocysteinemia in alternative nutrition is a consequence of vitamin B12 deficiency. In traditionally fed population, higher plasma homocysteine values is caused by folate deficiency. These conclusions are supported by a significantly negative linear correlation of homocysteine--folic acid levels (traditional nutrition) and homocysteine--vitamin B12 levels (alternative nutrition). In case of vitamin B6, a similar correlation was not found.