Quercetin is an antioxidant found in apple skins, cranberries, blueberries, onions, tea, and red wine. It might be an effective supplement for active men because it prevents illness and improves cell aerobic capacity. Supplementing with quercetin for seven days (1,000 mg per day) increased aerobic capacity by 4 percent and endurance capacity by 13 percent, compared to a placebo.
Other studies found that quercetin reduced inflammation, boosted the immune system, stimulated mental performance, protected the heart from coronary artery disease, and prevented protein breakdown. Quercetin builds up in the tissues, and we don’t know its safety or effectiveness in high concentrations.
In addition to enhancing muscle endurance, quercetin has also been found to increase testosterone levels and improve brain function.
TAKE THIS: 500 mg two times a day, with meals
Source: International Journal of Sport Nutrition and Exercise Metabolism, 20, 56-62