Timing of Turmeric Consumption and Oxidative Stress
Abstract Objectives The objective of this study was to compare the effects of morning vs. evening consumption of turmeric on urine markers of oxidative stress. The hypothesis stated that turmeric's action to modulate transcription of diurnally regulated genes coding for oxidative defense proteins would be influenced by the timing of turmeric consumption. Methods Participants prepared for each of four lab visits by consuming a low-antioxidant diet for two days and fasting for 12 hours. After providing a baseline urine sample, participants consumed one of two test meals (5 g turmeric + 180 ml egg white or egg white alone) at one of two clock times (morning or evening). A 1-week washout separated each visit. Urine was collected in the lab at 1 hour post-meal and at home for the following 5 hours. Urine biomarkers of oxidative stress were quantified using enzyme-linked immunosorbent assays; values were normalized to urine creatinine concentration. General Linear Models were used to predict biomarker levels over timepoints by turmeric intake and clock time. Results Participant (n = 4, 3 male) body mass index and age (median and range) were 33.3 (31.4–34.0) and 60.5 y (53–63). Urine 8-isoprostane concentration was significantly higher following consumption of the turmeric vs. control meal and after the 2-4-hour compared to 0-2-hour post-meal timepoint. The turmeric meal was not associated with urine malondialdehyde level. There was no significant interaction between turmeric consumption and clock time on either biomarker level. Conclusions Consuming turmeric at morning vs. evening did not differentially affect urine markers of oxidative stress. Studies of larger cohorts with measurements of oxidative stress markers over 24 hours would show whether these pilot results are generalizable. Funding Sources Academy of Nutrition and Dietetics Foundation, McCormick Science Institute Research Award; Academy of Nutrition and Dietetics Medical Nutrition Practice Group.