β-Carotene and α-tocopherol in healthy overweight adults; depletion kinetics are correlated with adiposity

Healthy overweight subjects (24 males, 68 females; mean age=48.8 years; body mass index=27.1+/-4.9) participated in a randomized, double-blind, placebo-controlled crossover study with two periods of 28-day supplementation using a nutritional product composed primarily of dehydrated juice concentrates from mixed fruits and vegetables (JuicePlus +). Compared with placebo, supplementation for 28 days increased concentrations of serum beta-carotene by 264% (P <0.001) and alpha-tocopherol by 14% (P < 0.01). After crossover of the active group to placebo, beta-carotene and alpha-tocopherol declined via first-order kinetics, with serum half-lives (t (1/2)) for beta-carotene and alpha-tocopherol determined to be 22.8+/-3.1 and 4.6+/-2.3 days, respectively. Depletion rates for beta-carotene correlated with adiposity (quartile 1, body mass index=21.96, t (1/2)=17.6 days vs. quartile 4, body mass index=37.87, t (1/2)=26.3 days; P < 0.05). In conclusion, the supplementation period resulted in significantly elevated levels of beta-carotene and alpha-tocopherol, indicating bioavailability. These increased levels persisted 2-4 weeks after supplementation was discontinued, and the rates of depletion were correlated with the levels of general adiposity.