Effects of high fruit-vegetable and/or low-fat intervention on plasma micronutrient levels

Objectives: Higher plasma micronutrient levels have been associated with decreased cancer risks. The objective of this study was to determine the relative effects of reduced fat and/or increased fruit-vegetable (FV) intakes on plasma micronutrient levels. Methods: Healthy, premenopausal women with a family history of breast cancer (n = 122) were randomized across four diet arms for one year in a 2 X 2 factorial design study: control, low-fat, high fruit-vegetable and combination low-fat/high FV diets. Levels of plasma micronutrients were measured in plasma at 0, 3, 6 and 12 months. Results: The high FV intervention, regardless of fat intake, significantly increased a-carotene, beta-carotene and vitamin C levels in plasma. Only the combination high FV, low-fat intervention significantly increased plasma beta-cryptoxanthin and zeaxanthin levels over time. Although a-tocopherol was not affected, a potential concern is that the low-fat intervention resulted in significantly decreased both gamma-tocopherol dietary intakes and plasma levels, regardless of whether or not FV intakes were concomitantly increased. Conclusions: Unlike a-tocopherol, gamma-tocopherol plasma levels were decreased by a low fat diet, perhaps because gamma-tocopherol is not generally added to foods nor widely used in vitamin E supplements. The decreased dietary intakes and plasma levels of gamma-tocopherol with a low-fat diet may have implications for health risks since the biological functions of the different tocopherol isomers have been reported to be distinct.