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 γ-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×time interaction for α-tocopherol intake by repeated-measures analysis of variance. Blueberry α-tocopherol (23.91±9.31 mg) was significantly (P<0.05) higher than placebo α-tocopherol intake (7.59±0.95 mg) on day 1, but not on day 30 (blueberry, α-tocopherol=9.04±2.35 mg, placebo, α-tocopherol=11.46±3.65 mg) by pairwise comparisons. Blueberry supplementation did not affect plasma vitamin concentrations or γ-tocopherol and vitamin C intakes, and may reduce α-tocopherol intake in those starting with a higher α-tocopherol intake, yet not altering athletes' eating habits.

• Blueberry antioxidants
• food selection assessment
• endurance exercise