8-Isoprostane F2alpha excretion is reduced in women by increased vegetable and fruit intake.

BACKGROUND

Health benefits associated with diets rich in vegetables and fruit (VF) are often attributed to the antioxidant activity of their constituent phytochemicals. However, in vivo evidence that VF actually reduce markers of oxidative stress is limited.

OBJECTIVE

An 8-wk dietary intervention was conducted to test the hypothesis that increased VF consumption decreases oxidative stress. Urinary excretion of 8-isoprostane F2alpha (8-iso-PGF2alpha) was used as an index of whole-body lipid peroxidation.

DESIGN

The diets evaluated had comparable amounts of all macronutrients but varied in their content of VF. After a 2-wk low-VF (3.0 servings/d) run-in diet, 246 women were randomly assigned to receive either 3.6 (low) or 9.2 (high) servings VF/d. The low-VF group was switched to the high-VF diet during the final 2 wk of the study. Blood and first-void urine specimens were obtained at baseline and at 2-wk intervals thereafter.

RESULTS

The run-in diet reduced 8-iso-PGF2alpha concentrations by 33% (P < 0.0001). The excretion of 8-iso-PGF2alpha with the low-VF diet remained the same as that with the run-in diet, whereas urinary concentrations of 8-iso-PGF2alpha were further reduced (P < 0.01) by the high-VF diet, either fed throughout the study or when the diet was switched from low to high VF (P = 0.05). The greatest reductions in 8-iso-PGF2alpha were observed in subjects in the highest quartile of baseline concentrations of 8-iso-PGF2alpha.

CONCLUSIONS

A significant reduction in the excretion of 8-iso-PGF2alpha was induced by the run-in diet and the high-VF diet. The degree of reduction was related to the subject's baseline urinary concentration of 8-iso-PGF2alpha.