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 alpha-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 alpha-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 alpha-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.