Abstract
Objective: To directly examine the contribution of vitamin C to the antioxidant potential of fruits and vegetables, the antioxidant effect of orange juice consumption (8 and 16 fl. oz.) was compared to the antioxidant effect of supplemental vitamin C (dosage equivalent to that supplied by 8 fl. oz. of orange juice).
Methods: Subjects (n = 11; 28.6 ± 2.1 years) received each treatment in a 3 × 3 randomized crossover design, and each two-week treatment was preceded by a two-week washout. During the entire trial, subjects restricted fruit and vegetable consumption to ≤3 servings per day except the vitamin C-rich foods (items containing >20 mg/serving), which were restricted to ≤3 servings per week. A fasting blood sample was collected at the end of each washout and each treatment period.
Results: Following washouts, plasma vitamin C and lipid peroxidation (plasma TBARS) were similar by treatment group and averaged 25.4 ± 3.6 μmol/L and 3.82 ± 0.10 nmol/mL respectively. Plasma vitamin C concentrations were similar following each treatment period, 37.9 ± 8.1, 45.8 ± 9.4, and 38.3 ± 12.4 μmol/L for the 8 and 16 fl. oz. orange juice treatments and the supplement treatment, respectively. All intervention treatments reduced plasma TBARS as compared to pretreatment values: −47% (p = 0.013), −40% (p = 0.083), and −46% (p = 0.015) for the 8 and 16 fl. oz. orange juice treatments and supplement treatment respectively.
Conclusions:These data indicate that the regular consumption of 8 fl. oz. orange juice or supplemental vitamin C (∼70 mg/day) effectively reduced a marker of lipid peroxidation in plasma.
This work was funded by the Lloyd S. Hubbard Nutrition Research Fund of the Arizona State University Foundation.
Notes
This work was presented in part at Experimental Biology ’02, April 2002, New Orleans, Louisiana.