By Kim Robson:
Most of the time, your immune system does an amazing job of protecting you from infectious microorganisms. While the idea of boosting immunity sounds good, actually doing so remains elusive. The immune system is just that — a system, and not a simple one. To function well, it requires balance and harmony, but researchers don’t fully understand the intricacies and interconnectedness of the immune response. They’re still figuring out how the immune system works and how to interpret measurements of immune function. We can measure certain blood components like lymphocytes or cytokines, but no one really knows what these measurements mean in terms of any individual’s ability to fight disease.
Researchers are studying the effects of many factors on immunity — from foods and herbal supplements to exercise and stress. There are thousands of products that claim to boost or support immunity, but the concept of boosting immunity actually makes little sense scientifically. Attempting to boost immune cells is especially complicated because in the immune system there are many different kinds of cells that respond to many different microbes in many different ways. Which cells to boost, and to what degree?
Some preparations have been found to alter some aspects of immune function, but there is no evidence yet that they actually bolster immunity to the point where you are better protected against infection and disease. Demonstrating whether a substance can enhance immunity is still a highly complicated matter. Researchers are investigating the immune boosting potential of a number of different substances:
Selenium – Combined with vitamin E, it may help prevent prostate cancer.
Vitamin A – Vitamin A deficiency is associated with impaired immunity and increased risk of infectious disease.
Vitamin B2 – Vitamin B2 enhances resistance to bacterial infections in mice, but how that translates to human immune response is unclear.
Vitamin B6 – Vitamin B6 deficiency can suppress the immune response, such as lymphocytes’ ability to mature and spin off into various types of T and B cells. Supplementing with moderate doses restores immune function, but megadoses don’t produce additional benefits.
Vitamin C – Vitamin C may work best in concert with other micronutrients rather than providing benefits by itself.
Vitamin D – Vitamin D, when produced by skin exposure to sunlight, signals an antimicrobial response to the bacterium responsible for tuberculosis.
Vitamin E – 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 not for diphtheria and pneumococcal vaccines.
Zinc – Zinc deficiency affects the ability of T cells and other immune cells to function as they should. Get 15–25 mg of zinc per day into your diet, but no more: too much zinc can inhibit the immune system.
Aloe vera – There’s no evidence yet that aloe vera can boost immune response.
Astragalus membranes – The quality of studies demonstrating the immune-stimulating properties of astragalus are poor. Plus, it can be dangerous.
Echinacea – Harvard Medical School physicians note that studies of the cold prevention capabilities of echinacea were not well designed and that it can cause potentially serious side effects. A 2005 study of 437 volunteers found that echinacea didn’t affect the rate, progress or severity of cold infections.
Garlic – In the lab, researchers have seen garlic work against bacteria, viruses and fungi. One promising 2006 study looked at cancer rates and garlic and onion consumption in southern European populations, and found a lower risk of some common cancers.
Ginseng – The National Center for Complementary and Alternative Medicine (NCCAM) is currently supporting research to understand Asian ginseng more fully.
Licorice root (Glycyrrhiza glabra) – Most studies of licorice root have been done in combination with other herbs. There are potential side effects and little is known about its benefits.
Probiotics – Probiotics are good bacteria, such as Lactobacillus and Bifidobacterium, which safely dwell in your digestive tract. Researchers at Harvard Medical School are finding evidence of a relationship between “good” bacteria and the immune system. Certain gut bacteria influence the development of aspects of the immune system, correcting deficiencies and increasing T cells. Exactly how the bacteria interact with the immune system isn’t well known.
The best ways to optimize your immune system are still about healthy living:
Get plenty of sleep and reduce stress. Sleep deprivation and stress overload increase the hormone cortisol, prolonged elevation of which suppresses immunity.
Avoid tobacco smoke. It undermines basic immune defenses, and raises the risk of bronchitis and pneumonia.
Drink less alcohol. Excessive consumption impairs the immune system.
Eat plenty of vegetables, fruits, nuts, seeds and whole grains. Boosting fruit and vegetable intake improves antibody response to vaccines.
Catch some rays. Sunlight triggers the skin’s production of vitamin D. This is far superior to supplements. 10-15 minutes of exposure (minus sunscreen) is all you need.
Eat medicinal mushrooms such as shiitake and maitake. A recent study showed that concentrated shiitake extract enhanced immune function in women with breast cancer.
Exercise regularly and maintain a healthy weight. Get outside in nature. Soil microbes exercise your immune system and have been found to have antidepressant effects on the brain.