Increasing the Vegetable Intake Dose Is Associated with a Rise in Plasma Carotenoids without Modifying Oxidative Stress or Inflammation in Overweight or Obese Postmenopausal Women

The optimal amount of vegetable consumption required to reduce chronic disease risk is widely debated. Intervention trials evaluating biological activity of vegetables at various doses are limited. We conducted a 3-dose, crossover feeding trial to test the hypothesis that vegetable intake is associated in a dose-dependent manner with increased plasma carotenoids and subsequently reduced oxidative stress and inflammation in 49 overweight, postmenopausal women. Participants were assigned in random order to 2 (130 g), 5 1287 g), and 10 (614 g) daily servings of fresh, greenhouse-grown vegetables for 3-wk intervals with a 4-wk washout period between treatments. Plasma total carotenoids significantly increased from 1.63 to 2.07 mu mol/L with a dose of 2 vegetable servings, from 1.49 to 2.84 mu mol/L with a dose of 5 vegetable servings, and from 1.40 to 4.42 mu mol/L with a dose of 10 vegetable servings (pre-post paired t tests, all P < 0.001). The change during each feeding period increased with each dose level (P < 0.001). Urine concentrations of 8-isoprostane F2 alpha, hexanoyl lysine, and serum high sensitivity C-reactive protein were not affected by any administered vegetable dose. In this variable-dose vegetable study, a dose-response for plasma carotenoids was demonstrated without significant change in oxidative stress and inflammation in overweight, postmenopausal women. J. Nutr. 141: 1827 1833, 2011.