Table 1.
Summary of immunonutrition supplements, underlying rationale, and recommendations *.
| Immunonutrition Supplement | Underlying Rationale | Recommendation Based on Current Evidence |
|---|---|---|
| Carbohydrate | Maintains blood glucose during exercise, lowers release of stress hormones; partially counters post-exercise inflammation and related immune changes. | Recommended: 30–70 g per hour of heavy exertion depending on exercise intensity and duration. |
| High fruit and vegetable intake, with extracts rich in polyphenols | Augment oxidative capacity, anti-viral defenses; gut-derived phenolics aid inherent defenses against long-term inflammation and oxidative stress, improve vascular health, and decrease risk of chronic disease. | Recommended, but the focus should be on long term benefits; extracts reserved for periods of heavy training and competition. |
| Bovine colostrums | Mix of immune, growth, and hormonal factors in fluid produced by the mammary glands for 24–72 h following calving improves immune function and lower illness risk. | Results are mixed; more data from well-designed studies needed. |
| Probiotics, prebiotics | Non-pathogenic bacteria in probiotics colonize the gut, improve intestinal microbial flora, and thereby enhance gut and systemic immune function, with a reduction in infection rates; prebiotics provide non-digestible food ingredients that promote the growth of beneficial microorganisms. | Results are mixed; more data from well-designed studies needed. |
| β-glucan | Receptors on intestinal wall immune cells interact with β-glucan improving innate immunity. | Results are mixed; more data needed comparing different sources. |
| n-3-PUFAs (fish oil) rich in EPA 20:5n3 and DHA 22:6n3 | Exert anti-inflammatory and immune-regulatory effects post-exercise; incorporated into cell membranes, partly replacing arachidonic acid and decreasing omega-6-derived mediators. | Results are mixed; data needed with longer duration and improved selection of outcome biomarkers. |
| Vitamin D | Plays a key role in both innate and acquired immunity through gene expression modulation; athletes may have low vitamin D levels, especially during the winter months. | Results are mixed; data needed on what actually constitutes a deficiency and benefits for correcting low levels. |
| Glutamine | Important immune cell substrate that may be lowered with prolonged exercise. | Results are mixed; more data from well-designed studies needed. |
| Vitamin E | Quenches exercise-induced reactive oxygen species (ROS) and augments immunity. | Not recommended; may be pro-oxidative and pro-inflammatory at high doses. |
| Vitamin C | Quenches ROS and augments immunity. | Not recommended; not consistently different from placebo. |
| Multiple vitamins and minerals (zinc, magnesium, iron, selenium, manganese) | Work together to quench ROS and reduce inflammation; co-factors for immune responses. | Not recommended; not different from placebo; balanced diet typically sufficient, but may be beneficial if the diet is insufficient. Concerns over blocking ROS signaling for training adaptations. |
| Amino acids (especially leucine, isoleucine, valine) | Metabolism provides nitrogen for glutamine synthesis. | Not recommended; lack of quality data from controlled studies to recommend amino acid supplementation with exercise. |
| Herbal supplements (e.g., ginseng, Echinacea) | Contain bioactive molecules that augment immunity and counter infection. | Not recommended; humans studies do not show consistent support within an athletic context. |