Don't Be Deceived!
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 don’t 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 doesn’t mean we should discount the benefits of all herbal preparations. Everyone’s immune system is unique. Each person’s physiology responds to active substances differently. So if your grandmother says she’s been using an herbal preparation for years that protects her from illness, who’s to say that it doesn’t? The problem arises when scientists try to study such a preparation among large numbers of people. The fact that it works for one person won’t show up in the research data if it’s 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, there’s 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 don’t 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 didn’t 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 didn’t 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 haven’t 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, it’s too early to recommend garlic as a way of treating or preventing infections or controlling cancer.
Ginseng. It’s 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 it’s 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 isn’t known. As more and more intriguing evidence comes in to support the link that intestinal bacteria bolster the immune system, it’s 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. You’ll 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.