How to boost your immune system- Part 02
Diet and supplements
What about diet?
Like any fighting force, the immune system army marches on its stomach. Immune system warriors need good, regular nourishment. Scientists have long recognized that people who live in poverty and are malnourished are more vulnerable to infectious diseases. Whether the increased rate of disease is caused by malnutritions effect on the immune system, however, is not certain. There are still relatively few studies of the effects of nutrition on the immune system of humans, and even fewer studies that tie the effects of nutrition directly to the development (versus the treatment) of diseases.
There are studies of the effects of nutritional changes on the immune systems of animals, but again there are few studies that address the development of diseases in animals as a result of changes in immunity. For example, one group of investigators has found that in mice, diets deficient in protein reduce both the numbers and function of T cells and macrophages and also reduce the production of immunoglobulin A (IgA) antibody.
are finding evidence of a relationship between such good bacteria and the immune system. For instance, it is now known that certain bacteria in the gut influence the
development of aspects of the immune system, such as
correcting
deficiencies and increasing the
numbers of certain
T cells.
There is some evidence that various micronutrient deficiencies for example, deficiencies of zinc, selenium, iron, copper, folic acid, and vitamins A, B6, C, and E alter immune responses in animals, as measured in the test tube. However, the impact of these immune system changes on the health of animals is less clear, and the effect of similar deficiencies on the human immune response has yet to be assessed. But the research at this stage is promising, at least for some of the micronutrients.
So what can you do? If you suspect your diet is not providing you with all your micronutrient needs maybe you dont like vegetables or you choose white bread over whole grains taking a daily multivitamin and mineral supplement brings health benefits of many types, beyond any possibly beneficial effects on the immune system. Taking megadoses of a single vitamin does not. More is not necessarily better. Researchers are investigating the immune boosting potential of a number of different nutrients.
Selenium. Some studies have suggested that people with low selenium levels are at greater risk of bladder, breast, colon, rectum, lung, and prostate cancers. A large-scale, multiyear study is currently in progress to look at the effects of combining selenium and vitamin E on prostate cancer prevention.
Vitamin A. Experts have long known that vitamin A plays a role in infection and maintaining mucosal surfaces by influencing certain subcategories of T cells and B cells and cytokines. Vitamin A deficiency is associated with impaired immunity and increased risk of infectious disease. On the other hand, according to one study, supplementation in the absence of a deficiency didnt enhance or suppress T cell immunity in a group of healthy seniors.
Vitamin B2. There is some evidence that vitamin B2 enhances resistance to bacterial infections in mice, but what that means in terms of enhancing immune response is unclear.
Vitamin B6. Several studies have suggested that a vitamin B6 deficiency can depress aspects of the immune response, such as lymphocytes ability to mature and spin off into various types of T and B cells. Supplementing with moderate doses to address the deficiency restores immune function, but megadoses dont produce additional benefits. And B6 may promote the growth of tumors.
Vitamin C. The jury is still out on vitamin C and the immune system. Many studies have looked at vitamin C in general; unfortunately, many of them were not well designed. Vitamin C may work in concert with other micronutrients rather than providing benefits alone.
Vitamin D. For many years doctors have known that people afflicted with tuberculosis responded well to sunlight. An explanation may now be at hand. Researchers have found that vitamin D, which is produced by the skin when exposed to sunlight, signals an antimicrobial response to the bacterium responsible for tuberculosis, Mycobacterium tuberculosis. Whether vitamin D has similar ability to fight off other diseases and whether taking vitamin D in supplement form is beneficial are questions that need to be resolved with further study.
Vitamin E. A study involving healthy subjects over age 65 has shown that increasing the daily dose of vitamin E from the recommended dietary allowance (RDA) of 30 mg to 200 mg increased antibody responses to hepatitis B and tetanus after vaccination. But these increased responses didnt happen following administration of diphtheria and pneumococcal vaccines.
Zinc. Zinc is a trace element essential for cells of the immune system, and zinc deficiency affects the ability of T cells and other immune cells to function as they should. Caution: While its important to have sufficient zinc in your diet (1525 mg per day), too much zinc can inhibit the function of the immune system.
Herbs and other supplements
Walk into a store, and you will find bottles of pills and herbal preparations that claim to support immunity or otherwise boost the health of your immune system. Although some preparations have been found to alter some components of immune function, thus far there is no evidence that they actually bolster immunity to the point where you are better protected against infection and disease. Demonstrating whether an herb or any substance, for that matter can enhance immunity is, as yet, a highly complicated matter. Scientists dont know, for example, whether an herb that seems to raise the levels of antibodies in the blood is actually doing anything beneficial for overall immunity.
But that doesnt mean we should discount the benefits of all herbal preparations. Everyones immune system is unique. Each persons physiology responds to active substances differently. So if your grandmother says shes been using an herbal preparation for years that protects her from illness, whos to say that it doesnt? The problem arises when scientists try to study such a preparation among large numbers of people. The fact that it works for one person wont show up in the research data if its not doing the same for a larger group.
Scientists have looked at a number of herbs and vitamins in terms of their potential to influence the immune system in some way. Much of this research has focused on the elderly, children, or people with compromised immune systems, such as AIDS patients. And many of the studies have had design flaws, which means further studies are needed to confirm or disprove the results. Consequently, these findings should not be considered universally applicable.
Some of the supplements that have drawn attention from researchers are these:
Aloe vera. For now, theres no evidence that aloe vera can modulate immune response. Because many different formulations and compounds have been used in studies, comparing the results is difficult. However, there is some evidence that topical aloe vera is helpful for minor burns, wounds, or frostbite, and also for skin inflammations when combined with hydrocortisone. Studies have found aloe vera is not the best option for treating breast tissue after radiation therapy.
Astragalus membranes. The astragalus product, which is derived from the root of the plant, is marketed as an immune-system stimulant, but the quality of the studies demonstrating the immune-stimulating properties of astragalus are poor. Furthermore, it may be dangerous.
Echinacea. An ocean of ink has been spilled extolling echinacea as an immune stimulant, usually in terms of its purported ability to prevent or limit the severity of colds. Most experts dont recommend taking echinacea on a long-term basis to prevent colds. A group of physicians from Harvard Medical School notes that studies looking at the cold prevention capabilities of echinacea have not been well designed, and other claims regarding echinacea are as yet not proven. Echinacea can also cause potentially serious side effects. People with ragweed allergies are more likely to have a reaction to echinacea, and there have been cases of anaphylactic shock. Injected echinacea in particular has caused severe reactions. A well-designed study by pediatricians at the University of Washington in Seattle found echinacea didnt help with the duration and severity of cold symptoms in a group of children. A large 2005 study of 437 volunteers also found that echinacea didnt affect the rate of cold infections or the progress and severity of a cold.
Garlic. Garlic may have some infection-fighting capability. In laboratory tests, researchers have seen garlic work against bacteria, viruses, and fungi. Although this is promising, there havent been enough well-designed human studies conducted to know whether this translates into human benefits. One 2006 study that looked at rates for certain cancers and garlic and onion consumption in southern European populations found an association between the frequency of use of garlic and onions and a lower risk of some common cancers. Until more is known, however, its too early to recommend garlic as a way of treating or preventing infections or controlling cancer.
Ginseng. Its not clear how the root of the ginseng plant works, but claims on behalf of Asian ginseng are many, including its ability to stimulate immune function. Despite the claims of a number of mainly small studies, the National Center for Complementary and Alternative Medicine (NCCAM) considers there have been insufficient large studies of a high enough quality to support the claims. NCCAM is currently supporting research to understand Asian ginseng more fully.
Glycyrrhiza glabra (licorice root). Licorice root is used in Chinese medicine to treat a variety of illnesses. Most studies of licorice root have been done in combination with other herbs, so its not possible to verify whether any effects were attributable to licorice root per se. Because of the potential side effects of taking licorice and how little is known about its benefits if any for stimulating immune function, this is an herb to avoid.
Probiotics.
There are hundreds of different species of bacteria in your digestive tract, which do a bang-up job helping you digest your food. Now researchers, including some at Harvard Medical School, are finding evidence of a relationship between such good bacteria and the immune system. For instance, it is now known that certain bacteria in the gut influence the development of aspects of the immune system, such as correcting deficiencies and increasing the numbers of certain T cells. Precisely how the bacteria interact with the immune system components isnt known. As more and more intriguing evidence comes in to support the link that intestinal bacteria bolster the immune system, its tempting to think that more good bacteria would be better. At least, this is what many marketers would like you to believe as they tout their probiotic products.
Probiotics are good bacteria, such as Lactobacillus and Bifidobacterium, that can safely dwell in your digestive tract.
Youll now find probiotics listed on the labels of dairy products, drinks, cereals, energy bars, and other foods. Ingredients touted as prebiotics, which claim to be nutrients that feed the good bacteria, are also cropping up in commercially marketed foods. Unfortunately, the direct connection between taking these products and improving immune function has not yet been made. Nor has science shown whether taking probiotics will replenish the good bacteria that get knocked out together with bad bacteria when you take antibiotics.
Another caution is that the quality of probiotic products is not consistent. Some contain what they say they do; some do not. In a 2006 report, the American Academy of Microbiology said that at present, the quality of probiotics available to consumers in food products around the world is unreliable. In the same vein, the FDA monitors food packages to make sure they dont carry labels that claim the products can cure diseases unless the companies have scientific evidence to support the claims.
Does this mean taking probiotics is useless? No. It means the jury is still out on the expansive health claims. In the meantime, if you choose to take a probiotic in moderation, it probably wont hurt, and the scientific evidence may ultimately show some benefit. (to be continued).
Source: Harvard Health Publications, Harvard Medical School
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