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Supplements with immunonutrients are popular. But not all supplements are evidence based. A small overview.
Physical activity influences the immune function and risk of certain types of infection such as upper respiratory tract infections. Elite endurance athletes are prime candidates for immunonutrition supplements to bolster immune systeme funktion in the face physiological stress. Here you will find a small overview about the single substances on the market: | substance | | proposed rationale | | Redommendation based on current evidence | | ω3 fatty acids | | Exerts anti-inflammatory effects post-exercise. | | Not recommended; no different from placebo. | | Vitamine E | | Quenches exercise-induced reactive oxygen species and augments immunity. | | Not recommended; may be prooxidative with heavy exertion. | | Vitamine C | | Quenches reactive oxygene species and augments immunity. | | Not recommended; no different from placebo. | | Glutamine | | Important immune cell energy substrate that is lowered with long exercise. | | Not recommended; body stores exceed exercise-lowering effects. | | Carbohydrates | | Maintains blood glucose during exercise, lowers stress hormones, and thus counters immune dysfunction. | | Recommended; but 60 g/hr of heavy exertion helps dampen immune inflammatory responses, but not immune dysfunction. | | β-Glucan | | Receptors found on immune cells, and animal data show supplementation improves innate immunity and reduces infection rates. | | Not recommended; human study with athletes showed no benefit. | | Quercetin | | In vitro studies show strong antiinflammatory, anti-oxidative, and anti-pathogenic effects. Animal data indicate increase in mitochondrial biogenis and endurance performance. | | Recommended; human studies show strong reduction in illness rates during heavy training and mild stimulation of mitochondrial biogenesis and endurance performance in untrained subjects. | | Quercetin with EGCG | | Flavonoid mixture promotes anti-inflammatory and anti-oxidative effects, and immune function improvement, above just quercetin alone. | | Recommended; human study showed strong anti-inflammatory effect, with modest anti-oxidative effect an improvement in innate immunity. |
References: Nieman DC. Immunonutrition support for athletes. Nutr Rev 66(6): 310-320, 2008
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