Immune Function

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Immune Function

Need to Know

Immune Function

Related Topics

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.

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.1 , 2 Nevertheless, immune function has been increased by stress-reducing techniques such as relaxation exercises, biofeedback, and other approaches,3 , 4 although not all studies have shown a significant effect.5

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

Choose fats wisely

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.6 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.7

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.8 , 9 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.10

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.11 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.12

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.13 However, diets high in omega-6 fatty acids have suppressed immunity in other reports.14 , 15

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.

Cut down on sugar

All forms of sugar (including honey) interfere with the ability of white blood cells to destroy bacteria.16 , 17 Animal studies suggest diets high in sucrose (table sugar) impair some aspects of immune function.18 , 19 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).

Give yogurt a go

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.20
Avoid alcohol binges Limit alcohol intake to avoid damaging effects to your immune system.

Avoid alcohol binges

Alcohol intake, including single episodes of moderate consumption, interferes with a wide variety of immune defenses.21 , 22 Alcohol’s immune-suppressive effect may be one mechanism for the association between alcohol intake and certain cancers23 and infections.24 , 25 However, moderate alcohol consumption (up to three to four drinks per day) has been associated in preliminary studies with either no risk26 or a decreased risk for upper respiratory infections in young nonsmokers.27

Supplements

What Are "Star" Ratings?

a7_3star   Reliable and relatively consistent scientific data showing a substantial health benefit.

a7_2star   Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

a7_1star   For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

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 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.


Supplement Amount Why
Andrographis
 48 to 60 mg andrographolides in two to three divided doses daily 3 stars   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.

3 stars  Andrographis

48 to 60 mg andrographolides in two to three divided doses daily

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.28 , 29 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,30 , 31 respectively.

Supplement Amount Why
Ashwagandha
 3 to 6 grams daily of the dried root as tea or in a capsule 2 stars   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.


2 stars  Ashwagandha

3 to 6 grams daily of the dried root as tea or in a capsule

Ashwagandha is considered a general stimulant of the immune system,32 and has been called a tonic or adaptogen33—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.

Supplement Amount Why
Asian Ginseng
 100 mg of a standardized extract twice per day 2 stars   Asian ginseng has a long history of use in traditional herbal medicine for preventing and treating conditions related to the immune system.


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. 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.34

Supplement Amount Why
Beta-Carotene
 25,000 to 100,000 IU per day for nonsmokers only 2 stars   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.

2 stars  Beta-Carotene

25,000 to 100,000 IU per day for nonsmokers only

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,35 , 36 but not all,37 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.38 Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research.39 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.40 , 41 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.42 , 43

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,44 but not several other measures of immunity.45

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.46 Beta-carotene has also prevented immune suppression from ultraviolet light exposure.47 Effects on immunodefiency in HIV-positive people have been inconsistent using beta-carotene.48 , 49

Supplement Amount Why
Echinacea
 3 to 5 ml of liquid extract three times per day 2 stars   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.


2 stars  Echinacea

3 to 5 ml of liquid extract three times per day

In general, human studies have found that echinacea taken orally stimulates the function of a variety of immune cells, particularly natural killer cells.50 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).51 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.52 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.

Supplement Amount Why
Eleuthero
 10 ml of tincture three times per day 2 stars   Eleuthero has historically been used to support the immune system.


2 stars  Eleuthero

10 ml of tincture three times per day

Eleuthero (Siberian ginseng) has also historically been used to support the immune system. Preliminary Russian research has supported this traditional use.53 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.

Supplement Amount Why
Glutamine
(Post-Exercise Infection)
 Refer to label instructions 2 stars   A study giving athletes glutamine, an amino acid important for immune system function, reported significantly fewer infections with glutamine.

2 stars  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.54 , 55 Endurance athletes are susceptible to upper respiratory tract infections after heavy exercise, which depletes glutamine levels in blood.56 Although the effects of glutamine supplementation on immune function after exercise have been inconsistent,57 , 58 a double-blind study giving athletes glutamine (2.5 grams after exercise and again two hours later) reported significantly fewer infections with glutamine.59

Supplement Amount Why
Probiotics
 10 billion colony-forming units a day of acidophilus or bifidobacteria-only for intestinal infections 2 stars   Probiotics help stimulate the intestine’s immune system and slow the growth of infectious organisms.


2 stars  Probiotics

10 billion colony-forming units a day of acidophilus or bifidobacteria-only for intestinal infections

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,60 , 61 including controlled62 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.63 , 64

Supplement Amount Why
Thymus Extracts
 1 to 1.5 mg thymus polypeptides per 2.2 lbs body weight 2 stars   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.

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. 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.65 , 66 , 67 , 68 , 69 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.70 , 71 , 72 , 73

Supplement Amount Why
Vitamin A
 Consult a qualified healthcare practitioner 2 stars   Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms.

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.74 However, most research shows that while vitamin A supplementation helps people prevent or treat infections in developing countries where deficiencies are common,75 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.76 , 77 , 78 , 79 , 80 , 81 , 82 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.83 A double-blind trial of vitamin A supplementation in Tanzanian children with pneumonia confirmed its lack of effectiveness for this condition.84 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.85

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.86 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.87 To what extent immune-boosting combinations of antioxidants actually reduce the risk of infection remains unknown.


Supplement Amount Why
Vitamin C
 Consult a qualified healthcare practitioner 2 stars   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.

2 stars  Vitamin C

Consult a qualified healthcare practitioner

Most,88 , 89 but not all,90 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.91 Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research.92 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 levels93 and enhancing the activity of certain immune cells.94 , 95 Two studies came to opposite conclusions about the ability of vitamin C to improve immune function in the elderly,96 , 97 and two other studies did not agree on whether vitamin C could protect people from hepatitis.98 , 99 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.100 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.101 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.102 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.103 To what extent immune-boosting combinations of antioxidants actually reduce the risk of infection remains unknown.


Supplement Amount Why
Astragalus
 Refer to label instructions 1 star   Complex polysaccharides in astragalus affect the immune system. One study showed that astragalus elevate antibody levels in healthy people.

1 star  Astragalus

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.104 Maitake has only been studied in animals as a way to increase immune function.105 The primary immuno-activating polysaccharide found in these mushrooms, beta-D-glucan, is well absorbed when taken orally106 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.

Supplement Amount Why
Beta-Glucan
 Refer to label instructions 1 star   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.

1 star  Beta-Glucan

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.107 , 108 , 109 , 110 , 111 In fact, there have been hundreds of research papers on beta-glucan since the 1960s.112 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.113 , 114 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.

Supplement Amount Why
Cat’s Claw
 Refer to label instructions 1 star   Substances found in cat’s claw, called oxyindole alkaloids, have been shown to stimulate the immune system.

1 star  Cat’s Claw

Substances found in cat’s claw, called oxyindole alkaloids have been shown to stimulate the immune system.115 However, little is known about whether this effect is sufficient to prevent or treat disease.

Supplement Amount Why
Cordyceps
 Refer to label instructions 1 star   Cordyceps has immune-strengthening actions and may be helpful in a wide range of conditions in which the immune system is weakened.


1 star  Cordyceps

Cordyceps has immune strengthening actions in human and animal studies.116 , 117 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.

Supplement Amount Why
DHEA
 Refer to label instructions 1 star   Supplementing with the hormone DHEA may improve immune functioning.


1 star  DHEA

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.118 Postmenopausal women have also shown increased immune functioning in just three weeks when given DHEA in double-blind research.119

Supplement Amount Why
Fo-Ti
 Refer to label instructions 1 star   Preliminary research suggests that fo-ti plays a role in a strong immune system and has antibacterial action.

1 star  Fo-Ti

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.

Supplement Amount Why
Green Tea
 Refer to label instructions 1 star   Green tea has stimulated production of immune cells and has shown anti-bacterial properties in some studies.

1 star  Green Tea

Green tea has stimulated production of immune cells and has shown anti-bacterial properties in animal studies.120 , 121 , 122 More research is needed to evaluate the effectiveness of green tea in protecting against infection and other immune system-related diseases.

Supplement Amount Why
Ligustrum
 Refer to label instructions 1 star   Ligustrum appears to stimulate the immune system and is often combined with astragalus in traditional Chinese medicine.


1 star  Ligustrum

The main active compound in ligustrum is ligustrin (oleanolic acid). Studies, mostly conducted in China, suggest that ligustrum stimulates the immune system.123 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.

Supplement Amount Why
Lycopene
 Refer to label instructions 1 star   Large amounts of the carotenoid lycopene have been shown to increase the activity of natural killer cells in the elderly.


1 star  Lycopene

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.124

Supplement Amount Why
Maitake
 Refer to label instructions 1 star   Complex polysaccharides present in maitake appear to increase immune function.


1 star  Maitake

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.125 Maitake has only been studied in animals as a way to increase immune function.126 The primary immuno-activating polysaccharide found in these mushrooms, beta-D-glucan, is well absorbed when taken orally127 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.

Supplement Amount Why
Noni
 Refer to label instructions 1 star   Studies show noni to have some immune-enhancing activity.


1 star  Noni

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.128 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.


Supplement Amount Why
Vitamin B12
 Refer to label instructions 1 star   A deficiency of vitamin B12 has been associated with decreased immune function. Restoring vitamin B12 levels may improve levels of immune cells.


1 star  Vitamin B12

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.129 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.

Supplement Amount Why
Whey Protein
 Refer to label instructions 1 star   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.


1 star  Whey Protein

A double-blind trial showed that 45 grams per day of whey protein increased blood glutathione levels in a group of HIV-infected people.130 Test tube131 , 132 and animal133 studies suggest that whey protein may improve some aspects of immune function.


Supplement Amount Why
Zinc
 Refer to label instructions 1 star   Zinc supplements have been reported to increase immune function. Some doctors recommend zinc supplements for people with recurrent infections.

1 star  Zinc

Most,134 , 135 but not all,136 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.137 Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research.138 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.139 , 140 This effect may be especially important in the elderly according to double-blind studies.141 , 142 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.143

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.144

References

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