Journal Title (Medline/Pubmed accepted abbreviation): Int. J. Sport Nutr. Exerc. Metab.
Page numbers: 338-346
Summary of background and research design:
Background: Quercetin is an antioxidant that is in the flavonoid family. It has been shown that the biological activities of flavonoids are greater when they are supplied with other flavonoids. Flavonoids also have shown anti-inflammatory activity and some believe that flavonoids may be potent enough to be used instead of nonsteroidal anti-inflammatory drugs (like ibuprofen). In a previous study, 2-wk supplementation with quercetin-containing “Q-chew” attenuated the inflammatory response to exercise.
Hypothesis: Does a one-time dose of “Q-chew” exhibit anti-inflammatory and/or immune-modulating properties in subjects completing a 2 hr run?
Subjects: In total, 20 runners completed the study- 11 male (40.5 ± 3.0 yrs old) and 9 female (25.8 ± 2.7 yrs old)
Experimental design: randomized, double-blind, placebo-controlled, crossover design
Treatments: Q-chew [including sugars, gums, flavors, etc. plus 250 mg quercetin, 100 mg isoquercetin, 30 mg epigallocatechin gallate (EGCG), 100 mg omega-3 fatty acids (55 mg eicosapentaenoic acid, EPA, and 45 mg docosahexaenoic acid, DHA) 250 mg vitamin C, and 10 mg niacinamide) or a placebo-chew (the same as the Q-chew minus the active ingredients plus color so they looked the same). One serving consisted of 4 chews.
Protocol: Beforehand, the participants were familiarized with the study procedures and assessed for VO2max and body composition. On test days, the participants consumed a standardized noon lunch and reported to the laboratory at 2:45 pm. At 3:00 pm, a baseline blood sample was acquired and they consumed one serving of one of the treatments. At 3:15, they began a treadmill run at 70-75% of their VO2max and ran for 2 hrs. For the last 15 min of the trial, the participants were asked to try to run as far as they could. Heart rate and metabolic factors were assessed at specific time points throughout the run. Blood samples were acquired immediately after the run and 1 hr after completion of the run. At least 3 wks separated the 2 visits.
Summary of research findings:
- Plasma quercetin increased significantly after exercise in the Q-chew trial and not the placebo trial (6337 µg/mL quercetin vs. 77.4 µg/mL for placebo).
- There was no difference in performance between the Q-chew and the placebo trial for males or females.
- Exercise caused a significant increase in white blood cells, C-reactive protein, and several inflammatory cytokines. The Q-chew did not appear to significantly attenuate any of these responses.
- Exercise also caused increases in other inflammatory activities such as monocytes phagocytosis, with no changes between the Q-chew and the placebo.
Key practice applications:
The Q-chew, when consumed 15 min before exercise, did not affect the immune response during exercise. In contrast, this same supplement taken for 2 wks before strenuous exercise (9 hrs of cycling), did indeed attenuate markers of inflammation. These 2 studies, taken together, suggest that flavonoids and/or omega-3 fatty acids may need to be consumed daily in order to build up or achieve a new steady-state level in the body before they can exhibit performance benefits.
Although these 2 studies were compared directly, there were differences other than the duration of supplementation between them, for example, the length of exercise. It is unknown whether performance benefits were seen after only 2 hrs when the subjects consumed the supplements for 2 wks.