The daily consumption of fruits and vegetables is a common dietary recommendation to support good health. We hypothesized that a commercially available encapsulated fruit and vegetable juice powder concentrate (FVJC) could support functional indices of health due to increased intake of various phytonutrients. This was a double-blind, randomized, placebo-controlled investigation of 59 healthy law students who consumed either FVJC or placebo capsules for 77 d. Blood was collected on d 1, 35, and 77 to examine the number of circulating alphabeta- and gammadelta-T cells, cytokine production, lymphocyte DNA damage, antioxidant status, and levels of carotenoids and vitamin C. A log of illnesses and symptoms was also kept. The FVJC group tended to have fewer total symptoms than the placebo group (P < 0.076). By d 77 there was a 30% increase in circulating gammadelta-T cells and a 40% reduction in DNA damage in lymphocytes in the FVJC group relative to the placebo group. Plasma levels of vitamin C and of beta-carotene, lycopene, and lutein increased significantly from baseline in the FVJC group as did plasma oxygen radical absorptive capacity (50%). Interferon-gamma produced by phorbol-stimulated lymphocytes was reduced 70% in the FVJC group, whereas other cytokines (IL-4, IL-6, transforming growth factor beta) were unchanged relative to treatment or time. FVJC consumption during this study period resulted in increased plasma nutrients and antioxidant capacity, reduction in DNA strand breaks, and an increase in circulating gammadelta-T cells.