This study investigated the effects of time-of-day of grape consumption on high-fat meal-induced oxidative stress.

Grape consumption acts on the immune system to produce antioxidant and anti-inflammatory effects. Since immune activity demonstrates circadian rhythmicity, with peak activity occurring during waking hours, the timing of grape intake may influence the magnitude of its antioxidant effect. This study followed a 2 x 2 factorial randomized, controlled design wherein healthy men and women (n = 32) consumed either a grape or placebo drink with a high-fat meal in the morning or evening. Urine was collected for measurements of biomarkers of oxidative stress and grape metabolites at baseline and post-meal at hour 1 and hours 1-6

Inclusion Criteria:

• Healthy
• Age 18-50 y

Exclusion Criteria:

• Employed in shift or night work
• Extreme early or late chronotype
• Presence of acute infection or chronic inflammatory disease
• Smoking
• Heavy aerobic exerciser
• Greater than moderate alcohol intake
• Pregnancy or lactation
• Use of non-steroidal anti-inflammatory medications or antioxidant dietary supplements.