2.6. Anthropometric Measurements, Urine Collection and Biomarker/Metabolite Analysis
OXIDATIVE STRESS
Upon arrival at the laboratory visit, height was measured to the nearest 0.1 cm using a stadiometer and weight was measured to the nearest 0.1 kg using a beam scale. Body mass index was calculated as (weight in kg)/(height in meters)A baseline urine sample was collected during the laboratory visit before test meal consumption. For the 5 h following test meal consumption, participants were instructed to drink only water and eat no food. A 1 h post-meal urine sample was collected in the laboratory before participants left for work/home, where they collected urine in a batch for the next 5 h. The urine collection schedule was based on published data demonstrating that oxidative stress biomarker levels show peak change due to spice intake within 5 h of consumption [Urine samples collected outside the laboratory were stored in a refrigerator or temporarily placed in a cooler before transfer to a refrigerator. Participants delivered home-collected samples in a cooler to the investigator within 12 h of the 5 h sample collection for storage at −80 °C before analysis.Urine was analyzed for a marker of oxidative stress, F2-isoprostane, and grape anti-inflammatory and antioxidant polyphenol metabolites (resveratrol, tartaric acid, catechin, and quercetin) using validated Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) methods and values were normalized to creatinine levels determined by enzyme-linked immunoassay kit. The time points for all urine analyses were baseline, 0–1 h, and 1–6 h periods. Research staff performing urine analyses were blinded to the intervention group of urine samples.