Immune Function (Holistic)

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About This Condition

The immune system is a complex network of tissues, organs, cells, and chemicals that protects the body from infection and illness. According to research or other evidence, the following self-care steps may be helpful.
  • Get the good bacteria

    Stimulate the intestine’s immune system and slow the growth of infectious organisms in the intestine by regularly eating yogurt and other foods containing live cultures, or take a supplement containing 10 billion colony-forming units a day of acidophilus or bifidobacteria

  • Use exercise wisely

    Take advantage of the benefits of moderate exercise on immune function—but be careful about prolonged or intense exercise, which can temporarily increase your risk of infection

  • Avoid alcohol binges

    Keep your alcohol intake low or moderate to avoid damaging effects to your immune system

About

About This Condition

The immune system is an intricate network of specialized tissues, organs, cells, and chemicals. The lymph nodes, spleen, bone marrow, thymus gland, and tonsils all play a role, as do lymphocytes (specialized white blood cells), antibodies, and interferon.

Two types of immunity protect the body: innate and adaptive. Innate immunity is present at birth and provides the first barrier against microorganisms. The skin, mucus secretions, and the acidity of the stomach are examples of innate immunity that act as barriers to keep unwanted germs away from more vulnerable tissues.

Adaptive immunity is the second barrier to infection. It is acquired later in life, such as after an immunization or successfully fighting off an infection. The adaptive immune system retains a memory of all the invaders it has faced. This is why people usually get the measles only once, although they may be repeatedly exposed to the disease. Unfortunately some bugs—such as the viruses that cause the common cold—“disguise” themselves and must be fought off time and again by the immune system.

Symptoms

Symptoms of decreased immune function include frequent colds and flus, recurring parasitic infections, initially mild infections that become serious, opportunistic infections (infections by organisms that are usually well controlled by a healthy immune system, such as toxoplasmosis, cryptococcosis, and cytomegalovirus), and cancer.

Healthy Lifestyle Tips

Both excessive thinness and severe obesity are associated with impaired immune responses.1 Obesity increases the risk of infection, at least in hospitalized patients, according to preliminary research.2 However, these effects may not occur with mild to moderate obesity in otherwise healthy people, and attempts to lose weight through dietary restriction may actually be harmful to the immune system.3 The detrimental effects of both appear to be offset when people regularly perform aerobic exercise.4 , 5

The effects of exercise on immune function depend on many factors, including frequency and intensity of exercise.6 Regular moderate physical activity has positive effects, at least on some measures of immunity, and has been shown to reduce risk of upper respiratory infection. However, very intense and prolonged exercise, such as running a marathon or overtraining, can, in the short term, actually increase the risk of developing infections.7 The positive effects of moderate exercise on immunity may also partly explain the apparent reduced susceptibility to cancer of physically active people.8

Holistic Options

The immune system is suppressed during times of stress. Chronic mental and emotional stress can reduce immune function, but whether this effect is sufficient to increase the risk of infection or cancer is less clear.9 , 10 Nevertheless, immune function has been increased by stress-reducing techniques such as relaxation exercises, biofeedback, and other approaches,11 , 12 although not all studies have shown a significant effect.13

Eating Right

The right diet is the key to managing many diseases and to improving general quality of life. For this condition, scientific research has found benefit in the following healthy eating tips.

Recommendation Why
Choose fats wisely
Opt for monounsaturated fats, such as olive oil, over other kinds of fats to ensure optimal immune function.

The effect of fats on the immune system is complex and only partially understood. Excessive intake of total dietary fat impairs immune response, but some types of fat may be neutral or even beneficial. For example, monounsaturated fats, as found in olive oil, appear to have no detrimental effect on the immune system in humans at reasonable dietary levels.

Research on the effect of the omega-3 fatty acids that are abundant in some fish, fish oils, and flaxseed oil is conflicting. Liquid diets containing omega-3 fatty acids used in hospitals for critically ill people have been shown to improve immune function and reduce infections. However, in one controlled study in healthy people, a low-fat diet improved or maintained immune function, but when fish was added to increase omega-3 fatty acid intake, immune function was significantly inhibited.

Supplementation with DHA (an omega-3 fatty acid found in fish oil) in healthy young men has been shown to decrease the activity of immune cells, such as natural killer (NK) cells, and to inhibit certain measures of inflammation in the test tube. The anti-inflammatory effects of DHA may be useful in the management of autoimmune disorders; however, such benefits need to be balanced with the potential for increased risk of infections. Other studies suggest that increased oxidative damage might be the reason for the negative effects on the immune system sometimes caused by fish oil, and that increased intake of antioxidants, such as vitamin E, could correct the problem.

As with omega-3 fatty acids, omega-6 fatty acids (as found in vegetable oils) have also produced conflicting effects on the immune system. Enriching a low-fat diet with omega-6 fatty acids did not impair immunity. However, diets high in omega-6 fatty acids have suppressed immunity in other reports.

In summary, low-fat diets with moderate levels of monounsaturated fat from olive oil appear least likely to compromise immune function and may provide small benefits. Conclusions about the desirability of diets high in either omega-3 or omega-6 fatty acid supplementation await further research.

Cut down on sugar
All forms of sugar (including honey) interfere with white blood cells’ ability to destroy bacteria, so cutting back is one way to give your immune system a boost.
All forms of sugar (including honey) interfere with the ability of white blood cells to destroy bacteria. Animal studies suggest diets high in sucrose (table sugar) impair some aspects of immune function. The importance of these effects in the prevention of infections in humans remains unclear.
Give yogurt a go
Many studies have shown immune-stimulating effects from yogurt that contains live cultures, such as Lactobacillus acidophilus and other friendly bacteria (probiotics).

Many studies, in both animals and humans, have demonstrated immune-stimulating effects from yogurt which contains live cultures, such as Lactobacillus acidophilus and other probiotics (friendly bacteria). The effects of probiotics observed in humans include increasing the activity of several types of white blood cells. In preliminary human studies, consumption of live probiotic-containing yogurt has been associated with a reduced incidence of several immune-related diseases, including cancer, infections of the stomach and intestines, and some allergic reactions.

Avoid alcohol binges
Limit alcohol intake to avoid damaging effects to your immune system.

Alcohol intake, including single episodes of moderate consumption, interferes with a wide variety of immune defenses. Alcohol’s immune-suppressive effect may be one mechanism for the association between alcohol intake and certain cancers and infections. However, moderate alcohol consumption (up to three to four drinks per day) has been associated in preliminary studies with either no risk or a decreased risk for upper respiratory infections in young nonsmokers.

Supplements

What Are Star Ratings?

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by some in the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

Supplement Why
3 Stars
Andrographis
48 to 60 mg andrographolides in two to three divided doses daily
Andrographis, with its immune system–enhancing actions, has been shown to reduce the severity of the common cold and may prevent the onset of a cold in healthy people.
Andrographis extract, either alone or combined with eleuthero extract, has been shown in a double-blind trial to successfully reduce the severity of the common cold. A double-blind study also suggests andrographis extract may prevent the onset of a cold in healthy people. These actions are thought to be due to the immune system enhancing actions of the active constituents known as andrographolides and eleutherosides, respectively.
3 Stars
Multivitamin
Follow label directions
 
3 Stars
Vitamin E
200 IU daily
Vitamin E enhances some measures of immune-cell activity in the elderly.

Most, but not all, double-blind studies have shown that elderly people have better immune function and reduced infection rates when taking a multiple vitamin-mineral formula. In one double-blind trial, supplements of 100 mcg per day of selenium and 20 mg per day of zinc, with or without additional vitamin C, vitamin E, and beta-carotene, reduced infections in elderly people, though vitamins without minerals had no effect. Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research. These studies suggest that trace minerals may be the most important micronutrients for enhancing immunity and preventing infections in the elderly.

2 Stars
Ashwagandha
3 to 6 grams daily of the dried root as tea or in a capsule
Ashwagandha stimulates the immune system and is considered a tonic or adaptogen—an herb with multiple actions that counteract the effects of stress and generally promote wellness.
Ashwagandha is considered a general stimulant of the immune system, and has been called a tonic or adaptogen—an herb with multiple, nonspecific actions that counteract the effects of stress and generally promote wellness. More research is needed to better evaluate these claims.
2 Stars
Asian Ginseng
100 mg of a standardized extract twice per day
Asian ginseng has a long history of use in traditional herbal medicine for preventing and treating conditions related to the immune system.
Asian ginseng has a long history of use in traditional herbal medicine for preventing and treating conditions related to the immune system. A double-blind study of healthy people found that taking 100 mg of a standardized extract of Asian ginseng twice per day improved immune function.
2 Stars
Beta-Carotene
25,000 to 100,000 IU per day for nonsmokers only
Beta-carotene has been shown to increase immune cell numbers and activity. It has also been shown to enhance cancer-fighting immune functions in healthy people.

Caution: Synthetic beta-carotene has been linked to increased risk of lung cancer in smokers. Until more is known, smokers should avoid all beta-carotene supplements.

Most, but not all, double-blind studies have shown that elderly people have better immune function and reduced infection rates when taking a multiple vitamin-mineral formula. In one double-blind trial, supplements of 100 mcg per day of selenium and 20 mg per day of zinc, with or without additional vitamin C, vitamin E, and beta-carotene, reduced infections in elderly people, though vitamins without minerals had no effect. Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research. These studies suggest that trace minerals may be the most important micronutrients for enhancing immunity and preventing infections in the elderly.

Beta-carotene and other carotenoids have increased immune cell numbers and activity in animal and human research, an effect that appears to be separate from their role as precursors to vitamin A. Placebo-controlled research has shown positive benefits of beta-carotene supplements in increasing numbers of some white blood cells and enhancing cancer-fighting immune functions in healthy people at 25,000–100,000 IU per day.

In double-blind trials in the elderly, supplementation with 40,000–150,000 IU per day of beta-carotene has increased natural killer (NK) cell activity, but not several other measures of immunity.

Controlled research has found that 50,000 IU per day of beta-carotene boosted immunity in people with colon cancer but in not those with precancerous conditions in the colon. Beta-carotene has also prevented immune suppression from ultraviolet light exposure. Effects on immunodefiency in HIV-positive people have been inconsistent using beta-carotene.

2 Stars
Echinacea
3 to 5 ml of liquid extract three times per day
Studies have found that echinacea stimulates the function of a variety of immune cells, particularly natural killer cells. Taking it appears to speed recovery from the common cold.
In general, human studies have found that echinacea taken orally stimulates the function of a variety of immune cells, particularly natural killer cells. The balance of evidence currently available from studies suggests that echinacea speeds recovery from the common cold, via immune stimulation (as opposed to killing the cold virus directly). Evidence on preventing the common cold with echinacea is largely negative, suggesting its immune-stimulating activity may be mild in generally healthy people. Other studies on oral echinacea have not found that it stimulates activity of the white blood cells known as neutrophils. Many doctors recommend 3 to 5 ml of tincture three times per day for up to two weeks to improve immune function. Echinacea in capsule form is also commonly available.
2 Stars
Eleuthero
10 ml of tincture three times per day
Eleuthero has historically been used to support the immune system.
Eleuthero (Siberian ginseng) has also historically been used to support the immune system. Preliminary Russian research has supported this traditional use. A double-blind study has shown that healthy people who take 10 ml of eleuthero tincture three times per day had an increase in certain T lymphocytes important to normal immune function. These effects have not been studied in people with lowered immune function. The amount of eleuthero used in this trial is exceptionally high, though no side effects were seen.
2 Stars
Glutamine (Post-Exercise Infection)
Refer to label instructions
A study giving athletes glutamine, an amino acid important for immune system function, reported significantly fewer infections with glutamine.
The amino acid glutamine is important for immune system function. Liquid diets high in glutamine have been reported in controlled studies to be more helpful to critically ill people than other diets. Endurance athletes are susceptible to upper respiratory tract infections after heavy exercise, which depletes glutamine levels in blood. Although the effects of glutamine supplementation on immune function after exercise have been inconsistent, a double-blind study giving athletes glutamine (2.5 grams after exercise and again two hours later) reported significantly fewer infections with glutamine.
2 Stars
Probiotics
10 billion colony-forming units a day of acidophilus or bifidobacteria-only for intestinal infections
Probiotics help stimulate the intestine’s immune system and slow the growth of infectious organisms.
Supplements of probiotics (friendly bacteria) such as Lactobacillus acidophilus, or the growth factors that encourage their development in the gastrointestinal tract may help protect the body from harmful organisms in the intestine that cause local or systemic infection according to published research, including controlled trials. The effective amount of probiotics depends on the strain used, as well as the number of viable organisms. Infectious diarrhea in children has been successfully reduced with supplements of friendly bacteria in several trials, some of which were double-blind.
2 Stars
Selenium
100 mcg daily with 20 mg zinc daily
Selenium supplements have been reported to help improve immune function in seniors.

Most, but not all, double-blind studies have shown that elderly people have better immune function and reduced infection rates when taking a multiple vitamin-mineral formula. In one double-blind trial, supplements of 100 mcg per day of selenium and 20 mg per day of zinc, with or without additional vitamin C, vitamin E, and beta-carotene, reduced infections in elderly people, though vitamins without minerals had no effect. Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research. These studies suggest that trace minerals may be the most important micronutrients for enhancing immunity and preventing infections in the elderly.

2 Stars
Thymus Extracts
1 to 1.5 mg thymus polypeptides per 2.2 lbs body weight
The thymus gland is responsible for many immune system functions. A thymus extract known as Thymomodulin has been shown to improve immune function in some people.
The thymus gland is responsible for many immune system functions. Preliminary studies suggest that a thymus extract known as Thymomodulin® may improve immune function, and double-blind trials in children and adults with a history of recurrent respiratory-tract infections have found reduced numbers of recurrent infections with Thymomodulin supplementation. Thymomodulin has also been shown in a double-blind study to improve immune function in cases of exercise-induced immune suppression, and in preliminary studies to improve immune function in people with diabetes and in elderly people.
2 Stars
Vitamin A
Consult a qualified healthcare practitioner
Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms.

Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms. However, most research shows that while vitamin A supplementation helps people prevent or treat infections in developing countries where deficiencies are common, little to no positive effect, and even slight adverse effects, have resulted from giving vitamin A supplements to people in countries where most people consume adequate amounts of vitamin A. Moreover, vitamin A supplementation during infections appears beneficial only in certain diseases. An analysis of trials revealed that vitamin A reduces mortality from measles and diarrhea, but not from pneumonia, in children living in developing countries. A double-blind trial of vitamin A supplementation in Tanzanian children with pneumonia confirmed its lack of effectiveness for this condition. In general, parents in the developed world should not give vitamin A supplements to children unless there is a reason to believe vitamin A deficiency is likely, such as the presence of a condition causing malabsorption (e.g., celiac disease). However, the American Academy of Pediatrics recommends that all children with measles be given short-term supplementation with high-dose vitamin A in cases of hospitalization, malnutrition, and other special circumstances determined by a doctor.

A combination of antioxidants vitamin A, vitamin C, and vitamin E significantly improved immune cell number and activity compared with placebo in a group of hospitalized elderly people. Daily intake of a 1,000 mg vitamin C plus 200 IU vitamin E for four months improved several measures of immune function in a preliminary study. To what extent immune-boosting combinations of antioxidants actually reduce the risk of infection remains unknown.

2 Stars
Vitamin C
Consult a qualified healthcare practitioner
Vitamin C stimulates the immune system. While taking it has only a small effect in preventing colds, it does significantly reduce the duration of a cold when taken at the onset.

Most, but not all, double-blind studies have shown that elderly people have better immune function and reduced infection rates when taking a multiple vitamin-mineral formula. In one double-blind trial, supplements of 100 mcg per day of selenium and 20 mg per day of zinc, with or without additional vitamin C, vitamin E, and beta-carotene, reduced infections in elderly people, though vitamins without minerals had no effect. Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research. These studies suggest that trace minerals may be the most important micronutrients for enhancing immunity and preventing infections in the elderly.

Vitamin C stimulates the immune system by both elevating interferon levels and enhancing the activity of certain immune cells. Two studies came to opposite conclusions about the ability of vitamin C to improve immune function in the elderly, and two other studies did not agree on whether vitamin C could protect people from hepatitis. However, a review of 20 double-blind studies concluded that while several grams of vitamin C per day has only a small effect in preventing colds, when taken at the onset of a cold, it does significantly reduce the duration of a cold. In controlled reports studying people doing heavy exercise, cold frequency was reduced an average of 50% with vitamin C supplements ranging from 600 to 1,000 mg per day. Thus, the overall effect of vitamin C on immune function is unclear, and its usefulness may vary according to the situation.

A combination of antioxidants vitamin A, vitamin C, and vitamin E significantly improved immune cell number and activity compared with placebo in a group of hospitalized elderly people. Daily intake of a 1,000 mg vitamin C plus 200 IU vitamin E for four months improved several measures of immune function in a preliminary study. To what extent immune-boosting combinations of antioxidants actually reduce the risk of infection remains unknown.

1 Star
Astragalus
Refer to label instructions
Complex polysaccharides in astragalus affect the immune system. One study showed that astragalus elevate antibody levels in healthy people.
Complex polysaccharides present in astragalus and in maitake and coriolus mushrooms appear to act as “immunomodulators” and, as such, are being researched for their potential role in AIDS and cancer. Presently, the only human studies on astragalus indicate that it can prevent white blood cell numbers from falling in people given chemotherapy and radiotherapy and can elevate antibody levels in healthy people. Maitake has only been studied in animals as a way to increase immune function. The primary immuno-activating polysaccharide found in these mushrooms, beta-D-glucan, is well absorbed when taken orally and is currently under investigation as a supportive tool for HIV infection. Results from future research will improve the understanding of the possible benefits of these mushrooms and their constituents.
1 Star
Beta-Glucan
Refer to label instructions
Beta-glucan activates white blood cells, which in turn can recognize and kill tumor cells, correct oxidative damage, and speed up recovery of damaged tissue.
Beta-glucan is a fiber-type polysaccharide (complex sugar) derived from the cell wall of baker’s yeast, oat and barley fiber, and many medicinal mushrooms, such as maitake. Numerous experimental studies in test tubes and animals have shown beta-glucan to activate white blood cells. In fact, there have been hundreds of research papers on beta-glucan since the 1960s. The research indicates that beta-1,3-glucan, in particular, is very effective at activating white blood cells known as macrophages and neutrophils. A beta-glucan–activated macrophage or neutrophil can recognize and kill tumor cells, remove cellular debris resulting from oxidative damage, speed up recovery of damaged tissue, and further activate other components of the immune system. Although the research in test tube and animal studies is promising, many questions remain about the effectiveness of beta-glucan as an oral supplement to enhance immune function in humans. Controlled trials are necessary to determine whether humans can benefit from beta-glucan, and in what amounts oral beta-glucan must be taken from meaningful effects.
1 Star
Cat’s Claw
Refer to label instructions
Substances found in cat’s claw, called oxyindole alkaloids, have been shown to stimulate the immune system.
Substances found in cat’s claw, called oxyindole alkaloids have been shown to stimulate the immune system. However, little is known about whether this effect is sufficient to prevent or treat disease.
1 Star
Cordyceps
Refer to label instructions
Cordyceps has immune-strengthening actions and may be helpful in a wide range of conditions in which the immune system is weakened.
Cordyceps has immune strengthening actions in human and animal studies. Further research is needed but it may be helpful in a wide range of conditions in which the immune system is weakened. The usual amount taken is 3 to 4.5 grams twice daily as capsules or simmered for 10 to 15 minutes in water for tea.
1 Star
DHEA
Refer to label instructions
Supplementing with the hormone DHEA may improve immune functioning.
The hormone DHEA affects immunity. In a controlled trial, a group of elderly men with low DHEA levels who were given a high level of DHEA (50 mg per day) for 20 weeks, experienced a significant activation of immune function. Postmenopausal women have also shown increased immune functioning in just three weeks when given DHEA in double-blind research.
1 Star
Fo-Ti
Refer to label instructions
Preliminary research suggests that fo-ti plays a role in a strong immune system and has antibacterial action.
Preliminary research suggests that plays a role in a strong immune system and has antibacterial action. More research is needed to further understand the potential importance of these effects.
1 Star
Green Tea
Refer to label instructions
Green tea has stimulated production of immune cells and has shown anti-bacterial properties in some studies.
Green tea has stimulated production of immune cells and has shown anti-bacterial properties in animal studies. More research is needed to evaluate the effectiveness of green tea in protecting against infection and other immune system-related diseases.
1 Star
Ligustrum
Refer to label instructions
Ligustrum appears to stimulate the immune system and is often combined with astragalus in traditional Chinese medicine.
The main active compound in ligustrum is ligustrin (oleanolic acid). Studies, mostly conducted in China, suggest that ligustrum stimulates the immune system. Ligustrum is often combined with astragalus in traditional Chinese medicine. Although used for long-term support of the immune system in people with depressed immune function or cancer, more research is needed to demonstrate the optimal length of time to use ligustrum.
1 Star
Lycopene
Refer to label instructions
Large amounts of the carotenoid lycopene have been shown to increase the activity of natural killer cells in the elderly.
Large amounts of the carotenoid lycopene have been shown to increase the activity of NK cells in the elderly. In a controlled trial, 15 mg of lycopene significantly increased NK cell concentration, but no other immune functions.
1 Star
Maitake
Refer to label instructions
Complex polysaccharides present in maitake appear to increase immune function.
Complex polysaccharides present in astragalus and in maitake and coriolus mushrooms appear to act as “immunomodulators” and, as such, are being researched for their potential role in AIDS and cancer. Presently, the only human studies on astragalus indicate that it can prevent white blood cell numbers from falling in people given chemotherapy and radiotherapy and can elevate antibody levels in healthy people. Maitake has only been studied in animals as a way to increase immune function. The primary immuno-activating polysaccharide found in these mushrooms, beta-D-glucan, is well absorbed when taken orally and is currently under investigation as a supportive tool for HIV infection. Results from future research will improve the understanding of the possible benefits of these mushrooms and their constituents.
1 Star
Noni
Refer to label instructions
Studies show noni to have some immune-enhancing activity.

Animal and test tube studies show noni to have some immune-enhancing activity. Specifically, the polysaccharide component has been shown to increase the release of immune-enhancing compounds that activate white blood cells to destroy tumor cells. The usual recommendation is 4 ounces of noni juice 30 minutes before breakfast (effectiveness is thought to be best on an empty stomach). Human studies are needed to confirm the usefulness of noni.

1 Star
Vitamin B12
Refer to label instructions
A deficiency of vitamin B12 has been associated with decreased immune function. Restoring vitamin B12 levels may improve levels of immune cells.
A deficiency of vitamin B12 has been associated with decreased immune function. In a controlled trial, people with vitamin B12 deficiency anemia were also found to have markedly decreased levels of white blood cells associated with immune function. Restoration of vitamin B12 stores by means of injections improved levels of these immune cells, suggesting an important role for vitamin B12 in immune function.
1 Star
Whey Protein
Refer to label instructions
Whey protein appears to improve some aspects of immune function. One trial showed that whey protein increased blood glutathione levels in a group of HIV-infected people.

A double-blind trial showed that 45 grams per day of whey protein increased blood glutathione levels in a group of HIV-infected people. Test tube and animal studies suggest that whey protein may improve some aspects of immune function.

1 Star
Zinc
25 mg daily
Zinc supplements have been reported to increase immune function. Some doctors recommend zinc supplements for people with recurrent infections.

Most, but not all, double-blind studies have shown that elderly people have better immune function and reduced infection rates when taking a multiple vitamin-mineral formula. In one double-blind trial, supplements of 100 mcg per day of selenium and 20 mg per day of zinc, with or without additional vitamin C, vitamin E, and beta-carotene, reduced infections in elderly people, though vitamins without minerals had no effect. Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research. These studies suggest that trace minerals may be the most important micronutrients for enhancing immunity and preventing infections in the elderly.

Zinc supplements have been reported to increase immune function. This effect may be especially important in the elderly according to double-blind studies. Some doctors recommend zinc supplements for people with recurrent infections, suggesting 25 mg per day for adults and lower amounts for children (depending on body weight). However, too much zinc (300 mg per day) has been reported to impair immune function.

While zinc lozenges have been shown to be effective for reducing the symptoms and duration of the common cold in some controlled studies, it is not clear whether this effect is due to an enhancement of immune function or to the direct effect of zinc on the viruses themselves.

References

1. Chandra RK. Nutrition and the immune system: an introduction. Am J Clin Nutr 1997;66:460-3S [review].

2. Stallone DD. The influence of obesity and its treatment on the immune system. Nutr Rev 1994;52:37-50.

3. Nieman DC, Nehlsen-Cannarella SI, Henson DA, et al. Immune response to obesity and moderate weight loss. Int J Obes Relat Metab Disord 1996;20:353-60.

4. Nieman DC, Henson DA, Nehlsen-Cannarella SL. Influence of obesity on immune function. J Am Diet Assoc 1999;99:294-9.

5. Scanga CB, Verde TJ, Paolone AM, et al. Effects of weight loss and exercise training on natural killer cell activity in obese women. Med Sci Sports Exerc 1998;30:1666-71.

6. Nieman DC. Exercise immunology: practical applications. Int J Sports Med 1997;18:S91-100 [review].

7. Nieman DC. Exercise and resistance to infection. Can J Physiol Pharmacol 1998;76:573-80 [review].

8. Shephard RJ, Shek PN. Associations between physical activity and susceptibility to cancer: possible mechanisms. Sports Med 1998;26:293-315 [review].

9. Herbert TB, Cohen S. Stress and immunity in humans: a meta-analytic review. Psychosom Med 1993;55:364-79 [review].

10. Palmblad JE. Stress-related modulation of immunity: a review of human studies. Cancer Detect Prev Suppl 1987;1:57-64 [review].

11. Kemeny ME, Gruenewald TL. Psychoneuroimmunology update. Semin Gastrointest Dis 1999;10:20-9 [review].

12. Halley FM. Self-regulation of the immune system through biobehavioral strategies. Biofeedback Self Regul 1991;16:55-74 [review].

13. Whitehouse WG, Dinges DF, Orne EC, et al. Psychosocial and immune effects of self-hypnosis training for stress management throughout the first semester of medical school. Psychosom Med 1996;58:249-63.