Effect of a blueberry nutritional supplement on macronutrients, food group intake, and plasma vitamin E and vitamin C in US athletes.

ABSTRACT

Antioxidants from a blueberry beverage may impact plasma vitamins. We examined vitamins/food selection in 12 college athletes during 30 days compared with placebo. Blood was collected before and after exercise at the beginning of the study (day 1) and then after a 30-day period of taking a daily supplemental beverage (day 30). The six trials involved blood that was drawn pre-beverage ingestion/pre-exercise (trials 1 and 4), post-beverage ingestion/pre-exercise (trials 2 and 5), and post-beverage ingestion/1 h post-exercise (trials 3 and 6), on day 1 (trials 1, 2, and 3) and day 30 (trials 4, 5, and 6). Analysis of variance revealed non-significant differences for macronutrient or gamma-tocopherol and vitamin C intakes by food frequency questionnaire or plasma vitamins by liquid chromatography. There was a trend (P = 0.083) in the group x time interaction for alpha-tocopherol intake by repeated-measures analysis of variance. Blueberry alpha-tocopherol (23.91 +/- 9.31 mg) was significantly (P < 0.05) higher than placebo alpha-tocopherol intake (7.59 +/- 0.95 mg) on day 1, but not on day 30 (blueberry, alpha-tocopherol = 9.04 +/- 2.35 mg, placebo, alpha-tocopherol = 11.46 +/- 3.65 mg) by pairwise comparisons. Blueberry supplementation did not affect plasma vitamin concentrations or gamma-tocopherol and vitamin C intakes, and may reduce alpha-tocopherol intake in those starting with a higher alpha-tocopherol intake, yet not altering athletes' eating habits.