Immune-enhancing ingredients, such as probiotics, dairy peptides, vitamins, minerals and botanicals, are gaining increasing recognition
By Amanda Archibald
Trip down the aisles of the recent Natural Products Expo, and you will quickly note the rising "buzz" around immune system health.
Health status is a reflection of immunity status; the stronger the immune system, generally, the better your health. Weaken the immune system and you are susceptible to illness. Recurring infections, fatigue, inflammation, allergic responses, chronic diarrhea and slow wound healing are some signs of an impaired immune system. Factors that impact immune status may include poor nutrition, environmental pollutants, stress and overuse of antibiotics.
The Importance of Gut Health
The gastrointestinal tract functions as a defense barrier. Gut microflora prevent translocation of harmful microorganisms through the gut wall, and maintain the integrity of the gut (mucosal) lining itself. Inulin fractions, or non-digestible oligosaccharides, resist absorption in the upper intestinal tract, rendering them available as a substrate for endogenous bacteria in the colon. Ensuing production of lactic acid and short chain carboxylic acids produce a lowered pH environment, which selectively stimulates the growth of gut-friendly bifidobacteria, and is less conducive to harmful bacteria.
Probiotics are beneficial bacteria found in a healthy gut. The genera most often used as probiotic supplements are acidophilus and bifidobacteria. Specific to immunity, probiotics appear to stimulate IgA, the chief antibody in the membranes of the gastrointestinal and respiratory tracts. They also stimulate the phagocytic activity of granulocytes. Ingestion of yogurt is associated with production of cytokines which stimulate both humoral and cellular immune responses. Evidence does exist to suggest that probiotics may decrease in rota-virus-induced diarrhea.
Bioactive biopolymers in mushrooms are present both as glucans with glycosidic linkages such as (1-3), (1-6)-beta-glucans and (1-3)-alpha-glucans, or bound to protein residues such as polysaccharide protein complexes. A research report compiled by Smith, Rowan and Sullivan in conjunction with Cancer Research UK (London) states that numerous bioactive polysaccharides or polysaccharide protein complexes appear to enhance innate or cell-mediated immune responses. According to the authors, "stimulation of the host immune defense systems by bio-active polymers from medicinal mushrooms has significant effects on the maturation, differentiation and proliferation of many kinds of immune cells in the host."1 More recently, research suggests these mushroom polysaccharides may have a cytotoxic effect on cancer cells themselves. Three anti-tumor polysaccharides, namely lentinan, schizophyllan, and protein-bound polysaccharide (or polysaccharopeptide), have received specific attention.2
Balanced production of eicosanoids, derived from the polyunsaturated EFAs omega-3 (n-3) and omega-6 (n-6), modulates response to injury, trauma and infection. Eicosanoids comprise four categories: prostaglandins, prostacyclins, leukotrienes and thromboxanes. Synthesis of each category may depend upon the type of physiological event, the tissue and, importantly, the availability of the EFAs from the diet.
Since the body cannot manufacture EFAs, the "raw material" must be provided by dietary sources. Omega-6 sources are more abundant than omega-3. Omega-3 fatty acids can be synthesized from omega-6 or linoleic acid. However, synthesis is dependent upon a (metabolically) highly competitive conversion step, thus rendering the pathway an inefficient source of omega-3 fatty acids.
Recognizing the importance of EFAs, Swanson Health Products' (Fargo, N.D.) MultiOmega is "formulated to deliver a synergistic balance of omega-3 and omega-6 essential fatty acids." In a similar vein, Nature's Path (Richmond, British Columbia) Organic Pumpkin Granola Cereal "contains omega-3 fats for overall heart health and immune function." Spectrum Naturals (a subsidiary of Spectrum Organic Products Inc., Petaluma, Calif.) produces an omega-3 mayonnaise, omega-3 vinaigrettes and a trans-fat-free butter and margarine substitute called Essential Omega Spread, all which contain flaxseed oil, one of the richest sources of omega-3 fatty acids found in nature, according to Leslie Newman, marketing and public relations consultant for Spectrum Organic Products Inc.
Enzymes and Micronutrients
Jacob Teitelbaum, M.D., director of the Annapolis Research Center for Effective Fibromyalgia/Chronic Fatigue Syndrome Therapies (Annapolis, Md.), believes in the critical role of enzymes and micronutrients in immune function. According to Teitelbaum, ineffective digestion and absorption directly stresses and weakens the immune system. He points to the sheer volume of antacid prescriptions as evidence of the "digestion problem" among Americans.
As part of his protocol to improve digestion (and subsequent immune function) for the antacid-dependant population, Teitelbaum recommends plant-derived digestive enzymes such as CompleteGest™ by Enzymatic Therapy (Green Bay, Wis.) and Similase® by Tyler (Gresham, Ore.). "Plant-based enzymes work more effectively than animal-based in the acid stomach environment," notes Teitelbaum. Up to 40% of digestion occurs before food leaves the stomach, and animal-based enzymes "do not even begin to work significantly until they get past the stomach because of the acidity," he adds.
On the topic of micronutrients, Teitelbaum emphasizes the importance of zinc and glutathione in immune function. Not only is a lack of zinc a common dietary deficiency, it also is easily depleted in the recurrent infections/illnesses that Teitelbaum observes in his patients.
Clinical nutritionist Ellen Speare, Wild Oats Markets Inc. (Boulder, Colo.), agrees that zinc deficiency is prevalent in people with recurrent immune problems. While fresh whole foods are a cornerstone of immune health, Speare additionally recommends that people get adequate intakes of manganese, essential fatty acids, and the antioxidants selenium, vitamin A and vitamin C. Others have backed this up. 3
Concurring with Teitelbaum, Carla Sorensen of the Whey Protein Institute (Eden Prairie, Minn.) emphasizes the role of glutathione in immune defense. Whey protein is naturally rich in the sulfur-containing amino acid cysteine, which serves as a precursor to glutathione production. Glutathione is a powerful antioxidant and, says Teitelbaum, a "suit of armor" for the immune system. According to Sorensen, "low glutathione levels are often seen in individuals with HIV, Parkinson's and Alzheimers disease."
A Different Perspective
Auto-immune disorders such as Celiac Disease are affected significantly by nutrition. In celiac disease (CD), food-derived gluten damages the mucosal lining of the gut by causing an immunologically toxic reaction. Constant exposure to gluten blunts effective nutrient absorption and, in time, depletes effective immune response. Cindy Kaplan, vice president of marketing, EnJoy Life Foods (Chicago) cites a study published in the Archives of Internal Medicine, "as many as 1:133 Americans are gluten intolerant, although only 10% are currently diagnosed".4 Review of Mintel's Global New Product Database (Chicago) indicates that only 10% of worldwide reported new gluten-free products were introduced in the U.S. between September 2002 and August 2003.
The Impact of at Least 5-a-Day
According to Rick Weissinger, senior communications manager with the Produce for Better Health Foundation (Newark, Del.), the research is very clear: Lack of most nutrients will eventually impair immune function.
Fruits and vegetables are naturally abundant sources of antioxidants and phytochemicals. Antioxidants, including carotenoids, flavonoids, vitamins C and E, and selenium, function as "damage controllers" that scavenge the free-radical by-products of the body's defense system. As scavengers, antioxidants prevent damage to immune cells and effectively further strengthen immune response.5
Some studies imply an immune-enhancement role for carotenoids. Too much histamine (a potent vasodilator) can adversely impact T-cells. Vitamin C and certain phytochemicals (flavonoids) can—respectively—reduce blood levels of histamine and inhibit its release.
Rising Botanical Stars
Discussing immune function, Mark Blumenthal, founder and executive director of the American Botanical Council (Austin, Texas), noted four botanicals of significance. Historically used to enhance energy, clinical trials using both Asian Ginseng and Eleuthero Ginseng (formerly known as Siberian Ginseng) appear to be immune modulators. Ginseng is thought to function as an adaptogen, which, according to Blumethal, "increases the biological response of an organism in a non-specific way, or helps the body to respond to non-specific stressors."
Significant research from Sweden using the Asian herb Andrographis has demonstrated the herb to be a safe and effective treatment for conditions related to colds and flu. Clinical trials published in Phytomedicine using an Andrographis-Eleuthero combination also demonstrated their effectiveness in reducing the severity and duration of cold and flu symptoms.6,7
Using Astragalus, a Chinese herb, a study performed with dogs 10 years ago found that dogs with cancer demonstrated the same response (effect) when treated with Astragalus as with Interleukin-2 (IL-2), an immune stimulant for cancer patients. Astragalus appears to strengthen the immune-stimulating effect of IL-2. Astragalus is also a potent antioxidant and a source of high-molecular-weight polysaccharides known to increase immune function. Blumenthal specifically tags this herb as one to monitor for future science and applications in the future.
Specific to Echinacea, Blumenthal states that despite popular opinion, there is no evidence that it works long-term, or that it can prevent colds and flu. Research does support its role in reducing the severity of colds and flu.