Table 24.2.
Summary of rationale and findings for selected immunonutritional supplements
| Immunonutritional supplement | Proposed rationale | Recommendation based on current evidence |
|---|---|---|
| Vitamin E | Quenches exercise-induced reactive oxygen species (ROS) and augments immunity | Not recommended; may be pro-oxidative with heavy exertion |
| Vitamin C | Quenches ROS and augments immunity | Not recommended; not consistently different from placebo |
| Multiple vitamin and minerals | Work together to quench ROS and reduce inflammation | Not recommended; not different from placebo; balance diet is sufficient |
| Glutamine | Important immune cell energy substrate that is lowered with prolonged exercise | Not recommended; body stores exceed exercise-lowering effects |
| Branched chain amino acids (BCAAs) | BCAAs (valine, isoleucine, and leucine) are the major nitrogen source for glutamine synthesis in muscle | Not recommended; data inconclusive, and rationale based on glutamine |
| Carbohydrates | Maintain blood glucose during exercise, lowers stress hormones, and thus counters immune dysfunction | Recommended; up to 60 g/h of heavy exertion helps dampen immune inflammatory responses, but not immune dysfunction |
| Bovine colostrums | Mixture of immune, growth and hormonal factors improve immune functions and the neuroendocrine system; lower illness risk | Jury still out, with mixed results |
| Probiotics | Improve intestinal microbial flora, and thereby enhance gut and systemic immune function | Jury still out, with mixed results |
| N-3 PUFA (fish oil) | Exert anti-inflammatory effects postexercise | Not recommended; not different from placebo |
| β-Glucan | Receptors found on immune cells, shows supplementation improve innate immunity and reduces infection rate | Not recommended; human studies with athletes do not show any benefits |
| Herbal supplements (e.g., Ginseng, Echinacea) | Contain bioactive molecules that augment immunity and counter infection rates | Not recommended; human studies do not show consistent support within an athletic context |
| Quercetin | In vitro studies show strong evidence for anti-inflammatory antioxidative and anti-pathogenic effects. Animal data indicate increase in mitochondrial biogenesis and endurance performance; reduction in illness | Recommended when mixed with other flavonoids and nutrients; human studies show strong reduction in illness rates during heavy training and mild stimulation of mitochondrial biogenesis and endurance performance in untrained subjects; anti-inflammatory and antioxidative effects when mixed with green tea extract and fish oil |
Reproduced from Walsh NP, Gleeson M, Pyne DB, Nieman DC, Dhabhar FS, Shephard RJ, Oliver SJ, Bermon S, Kajeniene A: Position statement. Part two: Maintaining immune health. Exerc Immunol Rev 2011, 17:64–103, with kind permission of Dr. Hinnak Northoff