Dietary Folate from Vegetables and Citrus Fruit Decreases Plasma Homocysteine Concentrations in Humans in a Dietary Controlled Trial

Abstract

Elevated total plasma homocysteine (tHcy) concentrations are considered a risk factor for neural tube defects (NTD) and cardiovascular disease. Supplementation with folic acid decreases the risk of women having children with NTD. In both sexes, it decreases tHcy levels. We investigated the efficacy of natural dietary folate in improving folate and homocysteine status. We performed a 4-wk dietary controlled, parallel design intervention trial with 66 healthy subjects (18-45 y) divided into 3 treatment groups: the dietary folate group, the folic acid group and the placebo group. Each day each group was fed a different diet. The dietary folate group received a diet high in vegetables and citrus fruit (total folate content approximately 560 microgram) plus a placebo tablet. The folic acid group received a diet naturally low in folate (approximately 210 microgram) plus 500 microgram folic acid and placebo tablet on alternate days, i.e., 250 microgram folic acid/d. And the placebo group received the same low-folate diet as the folic acid group plus a placebo tablet. After 4 wk of intervention, folate status improved, and tHcy concentrations decreased in both the dietary folate and the folic acid groups. From the amount of additional folate (350 microgram/d) and folic acid (250 microgram/d) consumed, the relative bioavailability of dietary folate compared to folic acid was calculated to be 60-98%, depending on the endpoint used. In conclusion, increasing the consumption of vegetables and citrus fruit, both good sources of folate, will improve folate status and decrease tHcy concentrations. This may contribute to the prevention of cardiovascular disease and NTD in the general population

Micronutrients: dietary intake v. supplement use

“…Many fruits and vegetables, in particular leafy green vegetables, are also good sources of folate. A study by Brouwer et al (1999) has examined the effect of a diet high in citrus fruit and vegetables on folate status and total plasma Hcy levels. Folate levels were found to be increased and total plasma Hcy decreased in those subjects receiving this diet compared with a low-folate diet.…”

Impaired Homocysteine Metabolism and Atherothrombotic Disease

“…Low folate intake, tobacco smoking, and alcohol excess lead to hyperhomocysteinemia, probably by altering folate metabolism and by depleting vitamin B 6 stores (Cravo et al, 1996;Nygård et al, 1995Nygård et al, , 1998Piyathilake et al, 1994). Additionally, heavy coffee consumption increases homocysteine levels whereas tea, vitamin supplements, vegetable and fruit intakes, and physical activity are inversely related to circulating homocysteine (Appel et al, 2000;Broekmans et al, 2000;Brouwer et al, 1999;Nygård et al, 1997bNygård et al, , 1998Rasmussen et al, 2000).…”

The folic acid metabolite L-5-methyltetrahydrofolate effectively reduces total serum homocysteine level in orthotopic liver transplant recipients: a double-blind placebo-controlled study

“…In the liver, part of the L-methylfolate undergoes the enterohepatic circulation and is reabsorbed by the intestine. L-Methylfolate is the common form of folate, which circulates in the blood until it is taken up by the cells, excreted or partly reabsorbed by the kidney (Sauberlich et al, 1987;Brouwer et al, 1999).…”