A Nutritional Approach to Immunity

From the September 1999 Nutrition Science News

by David Wolfson, N.D.

Supplements shore up defenses during cold and flu season

The human body is continually protecting itself from the outside world. To shield itself from harmful environmental stimuli, the body employs its cells, biochemicals, organs and tissues. The complex interaction of these physiological systems produces immunity. Some of these systems have dual roles: The digestive system, for example, not only extracts and absorbs nutrients from foods but also destroys pathogenic organisms that may be present in foods. Other immune system components are more focused: White blood cells are specifically designed to destroy invading organisms.

One of the immune system's more extraordinary features is its ability to respond to the environment. When a threat is encountered, the immune system can mount an attack specifically designed to neutralize it. This is demonstrated most clearly in the antigen-antibody interaction. Antigens are proteinlike substances that identify living matter, much like biochemical name tags. When a white blood cell encounters another living organism--a bacterium, virus or normal human cell--it checks the name tag. When the system is working properly, if the tag says anything other than "self," the white blood cell considers the organism a hostile invader. Other immune cells are alerted and information gleaned from the antigen is used to design antibodies precisely configured to destroy both the antigen and the organism that carried it into the body.

Defects in any of the components of the immune system can impair its ability to recognize and neutralize invading organisms and thus increase susceptibility to infectious disease.

How can immune systems be kept at peak operating efficiency? An important clue is contained in the work of Weston Price, D.D.S., a researcher who, almost 60 years ago, observed a high degree of immunity among native cultures he encountered as he traveled the world. Price described cultures free from tuberculosis (one of the most prevalent infections in his time), dental disease, cancer and arthritis in locations including Africa, the Andes Mountains, Melanesia and New Zealand. These highly resistant peoples invariably ate whole, unprocessed foods and were physically active. Price observed that when individuals from such cultures relocated to areas where refined and processed foods were prevalent, they began to contract infectious and degenerative diseases. Upon returning to their native villages their health and immune status recovered. [ 1 ]

Modern research supports Price's observations. Many studies show that immune function depends on nutrients found primarily in whole, unprocessed foods. [ 2 ] Researchers have also confirmed that physical activity and a healthy emotional state are essential for proper immune function. [ 3,4 ]

A healthy diet and lifestyle may be the cornerstones of a strong immune system, but what specific measures can be taken when a person is faced with an immune challenge such as the annual cold and flu season?

Nutrients for Immune Support

Fortunately, a wide variety of immune-enhancing nutritional and herbal supplements is available.

Co-Q10 is one nutrient that often goes unrecognized as an immune-system supporter. Immune cells divide more rapidly than most cells and are in constant need of repair and maintenance. All of this work requires energy, and Co-Q10 is a critical factor in energy production pathways. In both animal and human studies Co-Q10 has compensated for immune deficiencies caused by aging or disease. [ 5,6 ] One study showed Co-Q10 significantly improved immune function and reduced symptoms in a number of HIV-infected individuals. [ 7 ] Daily Co-Q10 doses range from 20 to 200 mg. I recommend 10 mg twice daily for maintenance, increasing to higher doses during an infection.

Vitamin A as retinol or beta-carotene is a recognized immune-supportive nutrient. Almost a dozen studies demonstrate vitamin A's ability to reduce the incidence and severity of infectious illnesses. [ 8,9 ] Vitamin A supports immunity by maintaining the integrity of the body's mucosal surfaces. Mucous membranes such as those of the respiratory and gastrointestinal tracts act as natural barriers to pathogens. Vitamin A also improves antibody responses and increases white blood cell proliferation. Adding 10,000-15,000 IU per day of vitamin A, or 25,000 IU of mixed carotenoids, to a healthy diet can help boost immune response. Up to 100,000 IU per day can usually be taken safely on a short-term basis. [ 10 ]Pregnant women and people with liver conditions, however, should always consult a health care provider before supplementing with vitamin A. In its retinol form, vitamin A has the potential to cause birth defects and liver toxicity.

Vitamin C is the most widely known immune-stimulating nutrient. Numerous studies show that vitamin C, also known as ascorbic acid, works on several levels to support immune function. In addition to enhancing the activity of immune cells, vitamin C acts as a cofactor in the production of collagen, the principal protein found in all connective tissues. By helping maintain the strength and integrity of connective tissue structures, vitamin C keeps infections from spreading throughout the body. [ 11 ]

I recommend 1 g of vitamin C daily as a preventive measure. Customers should increase their dose at the first sign of a cold, flu or other illness but should not exceed 10 g daily unless they are advised to do so by a health care practitioner. [ 12,13 ]

Vitamin E is present in higher concentrations in immune cells than in any other cells of the body. Interestingly, white blood cells often use free radicals to help destroy pathogenic organisms. The high concentrations of antioxidant nutrients, including vitamin E, allow the white blood cells to use the destructive power of free radicals without being harmed. Studies show that people with lower serum levels of vitamin E are significantly more susceptible to infection than those with higher levels [ 13 ] and that supplemental vitamin E can improve immune responses in both sick and healthy individuals. [ 14,15 ]I recommend 200­400 IU daily and up to 800 IU at the first sign of infection. [ 13-15 ]

Zinc accelerates the growth of immune cells while inhibiting the replication of the cold-causing rhinoviruses. [ 16 ] Zinc also helps maintain the health of the thymus gland and improves the function of lymphocytes and phagocytic immune cells, all of which are vital to immune system function. [ 17,18 ] Clinical trials confirm zinc's usefulness in combating infectious disease. In one study, zinc gluconate lozenges were tested against placebo in a group of 100 patients with cold symptoms. Each zinc lozenge contained 13.3 mg of elemental zinc. Patients took one lozenge every two hours while awake. Those in the zinc group experienced significantly less coughing, headaches, nasal congestion, hoarseness and sore throats than the placebo group. Side effects were minimal--mostly harmless reactions to the taste of the lozenge. [ 19 ] These positive effects of zinc in adults have not been proven in children.

Zinc supplementation can range from 15 mg daily for prevention to 100 mg daily for acute infections. If a cold is accompanied by a sore throat, recommend zinc lozenges. These are usually more effective because they bring the zinc in direct contact with oral mucosa. One cautionary note: Taking high doses of any mineral long-term can cause other mineral imbalances and zinc is no exception. A zinc-copper imbalance can be particularly problematic--several studies suggest that high levels of zinc relative to copper may promote atherosclerosis and increase mortality due to coronary artery disease. [ 20 ]

Probiotic microorganisms, although technically not nutrients, are nonetheless important to immune function. Lactobacillus and bifidobacteria species have been shown to increase numbers of circulating lymphocytes, [ 21 ] stimulate phagocytic activity of white blood cells, [ 22 ] elevate antibody responses [ 23 ] and increase production of immune-modulating chemicals such as gamma interferon. [ 24 ] I recommend probiotic products that also contain a prebiotic such as fructooligosaccharides (FOS). FOS are carbohydrates that support the growth of probiotic organisms in the gastrointestinal tract. A recent study in Lancet showed that oligosaccharide molecules can bind to pathogenic microbes, thereby preventing their attachment to host cells. [ 25 ] For immune support, direct your customers to refrigerated probiotic products that contain 3 billion to 4 billion organisms per gram. For maintenance I recommend 1 g either several times a week or daily. For therapeutic purposes, increase the dose to 1 g three times daily.

Herbs for Immune Support

Herbal medicines have been used throughout history to enhance human resistance to disease. Modern herb research and new understanding of the immune system have explained many mechanisms by which these herbs work.

Echinacea (Echinacea spp.), one of the most widely known immune-supporting herbs, exerts some direct antimicrobial action but primarily boosts immune-cell activity and prevents bacterial enzymes from breaking down the body's tissues. [ 26,27 ] Clinical trial results are mixed, some showing little or no activity, [ 28 ] others demonstrating a marked ability to reduce cold symptoms. [ 29 ] (For more on echinacea, see "Doctor's Insight" on page 411.)

Prescription for Wellness Dr. Wolfson recommends the following natural immune enhancers to ready your customers for the cold and flu season. Co-Q10 10 mg twice daily; 50-100 mg twice daily during illness Probiotics with FOS 4 billion organisms/day; 4 billion organisms three times/day during illness Vitamin A 10,000-15,000 IU/day (or 25,000 IU mixed carotenoids); 100,000 IU/day during short-term illness* Vitamin C 1 g/day; up to 10 g/day during illness Vitamin E 200-400 IU/day; 800 IU during illness Zinc 15 mg/day; 100 mg/day during illness, lozenges for sore throats *Pregnant women and people with liver conditions should always con- sult their health care provider before supplementing with vitamin A.

At the first signs of a cold or flu, several 1-mL droppers of echinacea tincture taken every two to three hours may help abort the illness. During the course of an infection, a similar dose can be taken at less frequent intervals. Standardized echinacea formulations should be taken according to package directions.

Berberine-containing herbs have long been used for their antibiotic action and toning effects on the respiratory tract. Barberry (Berberis vulgaris), goldenseal (Hydrastis canadensis) and Oregon grape (Berberis aquifolium) all contain the antimicrobial phytochemical berberine.

Studies confirm berberine's antimicrobial activity against a wide variety of bacterial, fungal and parasitic species. [ 27 ] In one study berberine was shown to block streptococci from adhering to epithelial cells, the type of cell found lining the respiratory passages. [ 30 ] This suggests berberine-containing herbs may be particularly useful in strep infections. Other studies have shown the compound has a protective effect on thymus gland cells [ 31 ] and supports other immune cells. [ 32 ] Any of the berberine-containing herbs can be taken on their own, or with echinacea and other immune-supportive herbs. All berberine-containing herbs should be avoided during pregnancy because they may cause premature uterine contractions.

Garlic (Allium sativum) has more lore surrounding its ability to fight illness than any other herb. In vitro and animal testing seem to support garlic's use as a broad-spectrum antimicrobial, [ 33,34 ] but there are few human clinical trials. Epidemiological evidence suggests garlic may reduce the incidence of certain types of cancer, [ 35 ] but whether this is the result of improved immune function is not clear. It seems prudent to include garlic in the diet on a regular basis as a preventive measure and to increase its consumption, either fresh or in extract form, during cold and flu season.

Other herbs are also reported to have either antimicrobial or immune-enhancing effects. Licorice (Glycyrrhiza glabra), St. John's wort (Hypericum perforatum) and Lomatium (Lomatium dissectum) seem particularly suited for treating viral infections. All three have demonstrated virucidal activity in vitro. [ 36,37 ] Licorice has also been shown to increase the activity of macrophages and natural killer cells--critical elements of the immune system. [ 38 ]People with high blood pressure, however, should consult a health care practitioner before using licorice. Astragalus (Astragalus membranaceus), ginseng (Panax ginseng), and several species of mushroom including shiitake (Lentinus edodes), reishi (Ganoderma ludidum) and maitake (Grifolia frondosa) have been used historically to increase resistance. Astragalus enhances T cell function. [ 39 ] Panax ginseng has been shown to increase numbers and activity of lymphocytes, neutrophils and T cells. [ 40 ] And shiitake, reishi and maitake mushrooms all contain polysaccharide and protein complexes that stimulate immune cells and their ability to produce antimicrobial substances. [ 41 ] All of these medicinal plants can be taken alone or in combination with other immune-supportive supplements.

Immune health is ultimately our last defense against disease-causing organisms. The antibiotics upon which we have grown so dependent do nothing to support our own resistance and in fact have created antibiotic-resistant organisms. If we are to maintain our ability to ward off harmful environmental organisms we must shift our focus from reliance on drugs to enhancing our innate immunity.

David Wolfson, N.D., is a naturopathic physician, nutrition educator, and writer as well as a consultant to the natural products industry.

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