Good scientific evidence
Ginseng: Several studies suggest that ginseng can effectively enhance immune system function.
Avoid ginseng if known allergy to plants in the Araliaceae family. There has been a report of a serious life-threatening skin reactions, possibly caused by contaminants in the ginseng formulation.
Zinc: Zinc appears to be an essential trace element for the immune system, but research on the effect of zinc supplementation on immune function is scant and mostly focused on patients with specific diseases. Zinc gluconate appears to exert beneficial effects on immune cells, improving CD3 and CD4 counts (white blood cells that help coordinate the immune response) and increasing CD4/CD8 ratios in children. There are relatively few studies that examine zinc levels and the effects of zinc supplementation on the health of the elderly population. Further research is needed before a firm conclusion can be made.
Zinc is generally considered safe when taken at the recommended dosages. Avoid zinc chloride since studies have not been done on its safety or effectiveness. While zinc appears safe during pregnancy in amounts lower than the established upper intake level, caution should be used since studies cannot rule out the possibility of harm to the fetus.
Unclear or conflicting scientific evidence
Arginine (L-arginine): Preliminary research results suggest that arginine supplementation may enhance the immune response elicited by the pneumococcal vaccine in older people. More studies are needed to confirm these results.
Avoid if allergic to arginine. Avoid with history of stroke, liver disease, or kidney disease. Avoid if pregnant or breastfeeding. Use cautiously if taking blood-thinning drugs (like warfarin), blood pressure drugs, or herbs or supplements with similar effects. Check blood potassium levels.
Astragalus: Astragalus has been suggested as an immune system stimulant in preliminary laboratory and animal research, and in traditional accounts. Reliable human studies are lacking. High quality human research is necessary before a firm conclusion can be drawn.
Avoid if allergic to astragalus, peas, or any related plants or with a history of Quillaja bark-induced asthma. Avoid with aspirin or aspirin products or herbs or supplements with similar effects. Avoid with inflammation (swelling) or fever, stroke, transplant, or autoimmune diseases (like HIV/AIDS). Stop use two weeks before surgery/dental/diagnostic procedures with a risk of bleeding and avoid use immediately after these procedures. Use cautiously with bleeding disorders, diabetes, high blood pressure, lipid disorders, or kidney disorders. Use cautiously with blood-thinners, blood sugar drugs, diuretics, or herbs and supplements with similar effects. Avoid if pregnant or breastfeeding.
Beta-carotene: Preliminary research of beta-carotene for immune system maintenance or stimulation shows mixed results. Further research is needed before a conclusion can be drawn.
Avoid if sensitive to beta-carotene, vitamin A, or any other ingredients in beta-carotene products.
Cat's claw: A few early studies suggest that cat's claw may boost the immune system. However, results from different studies have not agreed with each other. Therefore, further research is necessary in order to determine whether cat's claw can effectively enhance the immune response.
Avoid if allergic to Cat's claw, Uncaria plants, or plants in the Rubiaceae family, such as gardenia, coffee, or quinine. Avoid with a history of conditions affecting the immune system (such as AIDS, HIV, some types of cancer, multiple sclerosis, tuberculosis, rheumatoid arthritis, lupus). Use cautiously with bleeding disorders, history of stroke, or if taking drugs that may increase the risk of bleeding. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Avoid if pregnant or breastfeeding. Cat's claw may be contaminated with other Uncaria species. Reports exist of the potentially toxic Texan grown plant Acacia gregii being substituted for cat's claw.
Copper: Copper is involved in the development of immune cells and immune function in the body. Severe copper deficiency appears to have adverse effects on immune function, although the exact mechanism is not clear.
Avoid if allergic or hypersensitive to copper. Avoid use of copper supplements during the early phase of recovery from diarrhea. Avoid with hypercupremia, occasionally observed in disease states including cutaneous leishmaniasis, sickle-cell disease, unipolar depression, breast cancer, epilepsy, measles, Down syndrome, and controlled fibrocalculous pancreatic diabetes (a unique form of secondary diabetes mellitus). Avoid with genetic disorders affecting copper metabolism such as Wilson's disease, Indian childhood cirrhosis, or idiopathic copper toxicosis. Avoid with HIV/AIDS. Use cautiously with water containing copper concentrations greater than 6 milligrams/liter. Use cautiously with anemia, arthralgia, and muscle pain. Use cautiously if taking oral contraceptives. Use cautiously if at risk for selenium deficiency. The recommended dietary allowance (RDA) is 1,000 micrograms for pregnant women. The RDA is 1300 micrograms for breastfeeding women.
Echinacea: Echinacea has been studied alone and in combination preparations for immune system stimulation (including in patients receiving cancer chemotherapy). It remains unclear if there are clinically significant benefits. Additional studies are needed in this area before conclusions can be drawn regarding safety or effectiveness.
Avoid if allergic to plants in the Asteraceaeor Compositaefamily (ragweed, chrysanthemums, marigolds, daisies). Avoid Echinacea injections. Avoid if history of liver disease or if taking amoxicillin. Avoid in organ transplant recipients. Use cautiously if driving or operating heavy machinery or if history of asthma, diabetes, conditions affecting the immune systems (like lupus, TB, AIDS-HIV), and rheumatologic conditions (rheumatoid arthritis). Avoid if pregnant or breastfeeding. Tinctures may contain large amounts of alcohol.
Gamma linolenic acid (GLA): Few clinical trials have investigated the effect of GLA on immune responses in healthy human subjects. Results from one randomized clinical trial suggest that GLA, as blackcurrant seed oil, may offer some benefits. Further, well-designed clinical trials are required before definite conclusions can be made.
Use cautiously with agents that increase the risk of bleeding like anticoagulants and anti-platelet drugs. Avoid if pregnant or breastfeeding.
Goldenseal: Goldenseal is sometimes suggested to be an immune system stimulant. However, there is little human or laboratory evidence in this area. More research is needed before a firm conclusion can be drawn.
Avoid if allergic or hypersensitive to goldenseal or any of its constituents, like berberine and hydrastine. Use cautiously with bleeding disorders, diabetes, or low blood sugar. Avoid if pregnant or breastfeeding.
Maitake mushroom: Animal and laboratory studies suggest that beta-glucan extracts from maitake may alter the immune system. However, maitake has not been studied thoroughly in humans and its effects are not well known. Because it has been used historically as a food, it is thought that low doses may be safe. Avoid if allergic or hypersensitive to Grifola frondosa (maitake). Use caution with a history of low blood pressure, diabetes, or with drugs, herbs, or supplements that treat such conditions. Avoid if pregnant or breastfeeding.
Massage: Preliminary evidence suggests that massage therapy may preserve immune function. Further research is needed before a firm conclusion can be made.
Avoid with bleeding disorders, low platelet counts, or if taking blood-thinning medications (such as heparin or warfarin). Areas should not be massaged where there are fractures, weakened bones from osteoporosis or cancer, open/healing skin wounds, skin infections, recent surgery, or blood clots. Use cautiously if history of physical abuse or if pregnant or breastfeeding. Massage should not be used as a substitute for more proven therapies for medical conditions. Massage should not cause pain to the client.
Meditation: Preliminary research reports increased antibody response after meditation. Further study is needed to confirm these findings.
Use cautiously with underlying mental illnesses. People with psychiatric disorders should consult with their primary mental healthcare professional(s) before starting a program of meditation, and should explore how meditation may or may not fit in with their current treatment plan. Avoid with risk of seizures. The practice of meditation should not delay the time to diagnosis or treatment with more proven techniques or therapies, and should not be used as the sole approach to illnesses.
Mistletoe: A few small trials found mistletoe to be promising as an immunostimulant in individuals with the common cold. Further research is needed to confirm these results.
Avoid if allergic or hypersensitive to mistletoe or to any of its constituents. Anaphylactic reactions (life threatening) have been described after injections of mistletoe. Avoid with acute highly febrile inflammatory disease, thyroid disorders, seizure disorders, or heart disease. Use cautiously with diabetes, glaucoma, or with cholinergics.
Probiotics: Lactobacillus in fermented milk, low-fat milk, or lactose-hydrolyzed low-fat milk may enhance immune function. Bifidobacterium may as well, including in the elderly. However, commercially produced yogurt may not yield similar benefits. There is some evidence that probiotics added during food preparation (e.g. waffles with Enterococcus faecium M-74 added) may enhance immune functioning. More studies are needed, particularly with yogurt, before a firm conclusion can be made.
Probiotics are generally considered safe and well-tolerated. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.
Vitamin A (retinol): Vitamin A deficiency may compromise immunity, but there is no clear evidence that additional vitamin A supplementation is beneficial for immune function in patients who are not vitamin A deficient.
Avoid if allergic or hypersensitive to vitamin A. Vitamin A toxicity can occur if taken at high dosages. Use cautiously with liver disease or alcoholism. Smokers who consume alcohol and beta-carotene may be at an increased risk for lung cancer or heart disease. Vitamin A appears safe in pregnant women if taken at recommended doses. Use cautiously if breastfeeding because the benefits or dangers to nursing infants are not clearly established.
Vitamin B6 (pyridoxine): Vitamin B6 is important for immune system function in older individuals. One study found that the amount of vitamin B6 required to reverse immune system impairments in elderly people was more than the current recommended dietary allowance (RDA). Well-designed clinical trials on vitamin B6 supplementation for this indication are needed before a recommendation can be made.
Some individuals seem to be particularly sensitive to vitamin B6 and may have problems at certain doses. Avoid excessive dosing. Vitamin B6 is likely safe when used orally in doses not exceeding the RDA. The RDA for pregnant women is 1.9 milligrams per day. There is some concern that high-dose pyridoxine taken by a pregnant mother can cause seizures in a newborn. The RDA in breastfeeding women is 2 milligrams per day.
Vitamin E: Studies of the effects of vitamin E supplementation on immune system function have yielded mixed results. Further research is needed before a clear conclusion can be drawn.
Avoid if allergic or hypersensitive to vitamin E. For short periods of time, vitamin E supplementation is generally considered safe at doses up to 1,000 milligrams per day. Avoid doses higher than 1,000 milligrams a day. Avoid with retinitis pigmentosa (loss of peripheral vision). Use cautiously with bleeding disorders. The recommended dose of vitamin E for pregnant women of any age is 15 milligrams, and for breastfeeding women of any age is 19 milligrams. Use beyond this level in pregnant women is not recommended.
Fair negative scientific evidence
DHEA (dehydroepiandrosterone): DHEA (dehydroepiandrosterone) is a naturally occurring hormone that is produced by the adrenal glands. Some textbooks and review articles have suggested that DHEA can stimulate the immune system. However, current scientific evidence does not support this claim.
Avoid if allergic to DHEA. Avoid with a history of seizures. Use cautiously with adrenal or thyroid disorders or if taking anticoagulants or drugs, herbs, or supplements for diabetes, heart disease, seizure, or stroke. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Avoid if pregnant or breastfeeding.
Lycopene: It has been proposed that lycopene and other carotenoids, such as beta-carotene, may stimulate the immune system. However, several studies of lycopene supplements and tomato juice intake in humans report no effects on the immune system.
Avoid if allergic to tomatoes or to lycopene. Due to a lack of conclusive data, avoid if pregnant or breastfeeding.
Currently, there is no known method of prevention for antibody deficiencies that are inherited.
The pneumococcal vaccine and pneumococcal 7-valent conjugate vaccine may be beneficial for patients who have antibody deficiencies. Patients should consult their healthcare providers to determine whether vaccinations are recommended.
Avoiding close contact with individuals who have contagious illnesses may help reduce the risk of acquiring infections.
Practicing good hygiene and regularly washing the hands with soap and water may help reduce the risk of acquiring infections.