Mixed fruit and vegetable intake and homocysteine in men - Dietary Composition

Nutrition Research Newsletter, August, 2003

Fruit and vegetable consumption is inversely associated with coronary heart disease (CHD) risk. There remains scientific debate about the contribution of specific dietary constituents to the reduction in CHD risk. It has been suggested that the association of a lower rate of CHD with the intake of fruit and vegetables is attributed to the displacement of foods that are high in sodium, energy density and fat, particularly saturated fat. In addition, fruit and vegetables are recognized sources of a number of nutrients that may interact to reduce LDL cholesterol, blood pressure, and homocysteine and to improve antioxidant status and endothelial function. The aims of the present study were to determine the bioavailability of selected carotenoids and vitamins from a mixed concentrate of dehydrated fruit and vegetable juice and the effects of antioxidant status, homocysteine, plasma lipids, and insulin resistance in men.

Subjects (n=32) participated in a double-blind, randomized, placebo-controlled, crossover trial, consisting of two intervention periods of 6 week separated by a 3-week wash-out period. They were randomly assigned to one of two groups to receive either a mixed fruit and vegetable supplement produced from dehydrated juice concentrates, or a placebo. Each subject provided 10 blood samples over a period of 15 week. All subjects completed a food-frequency questionnaire (FFQ).

The degree of compliance was estimated as the difference between the number of capsules issued and the number of capsules returned. Consistent with the high degree of compliance, plasma amino acid (AA) concentrations increased significantly after supplementation. Plasma beta-carotene, retinol and alpha-tocopherol increased significantly. The change in alpha-tocopherol, but not retinol, remained significant after adjustment for cholesterol concentrations. Despite the high intake of folic acid at baseline, serum folate concentrations increased by 78.8% after supplementation. Concurrent with the rise in serum folate, plasma homocysteine decreased by 8.4%; the reduction occurred in 23 of 32 subjects. Plasma glucose, insulin, and insulin resistance were unaffected by supplementation. Similarly, plasma total cholesterol, total triglycerides, LDL cholesterol, and HDL cholesterol were not affected.

The results of the present study show that a mixed fruit and vegetable supplement produced from dehydrated juice provides a source of bioavailable vitamins and beta-carotene, and lowers the risk of heart disease by decreasing the concentration of plasma homocysteine.

S Samman, G Sivarajah, J Man, Z Ahmad, P Petocz, I Caterson. A mixed fruit and vegetable concentrate increases plasma antioxidant vitamins and folate and lowers plasma homocysteine in men. J Nutr 133:2188-2193 (July 2003) [Correspondence: E-mail: Samir Samman: s.samman@mmb.usyd.edu.au]