Carol S Johnston1, Candice L Dancho, Gail M Strong. 1. Department of Nutrition, Arizona State University East, 7001 E. Williams Field Road, Mesa, AZ 85212, USA. carol.johnston@asu.edu
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 x 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 < or =3 servings per day except the vitamin C-rich foods (items containing >20 mg/serving), which were restricted to < or =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 micromol/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 micromol/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 ( approximately 70 mg/day) effectively reduced a marker of lipid peroxidation in plasma.
RCT Entities:
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 x 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 < or =3 servings per day except the vitamin C-rich foods (items containing >20 mg/serving), which were restricted to < or =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 micromol/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 micromol/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 ( approximately 70 mg/day) effectively reduced a marker of lipid peroxidation in plasma.