Nutritional Immunity Enhancements

By Marie Spano, M.S., R.D., Contributing Editor

Nutrition has a profound effect on immune-system function. In fact, 70% of the immune system is located in the digestive system, so a digestive system that is operating in a healthy fashion is only going to help the immune system," notes Carl Freund, vice president of consumer products, Ganaden, Cleveland. Therefore, immune-boosting products, from vitamins to probiotics to phytochemicals, are rising market stars. But the science needs to support the marketing claims.

Vital vitamins

Vitamin A is essential for maintaining the lining of mucous membranes, helping immune-system cells fight infections more effectively and regulating the immune system (Nutrition and Health, 1996; 10(4):285-312). Though vitamin A can be toxic in very large doses, provitamin A carotenoids are considered safe because the bodys conversion to vitamin A stops when stores are full. However, because of conflicting studies about the potential adverse effects of beta-carotene in some populations, the Institute of Medicine Food and Nutrition Board, Washington, D.C., indicates that beta-carotene is not advisable for the general population

Epidemiological studies have linked inadequate vitamin D levels to a greater susceptibility of chronic infections and autoimmune diseases such as type 1 diabetes (Current Opinions in Pharmacology, 2010; 10:482-496). And, because many experts and scientific papers describe a state of vitamin D deficiency and insufficiency across the globe (American Family Physician, 2009; 80:841-846), the media attention to vitamin D has put this vitamin on the radar of many consumers.

Vitamin E affects the immune system, and supplementation above currently recommended levels can improve overall immune-system function and reduce the rate of upper-respiratory infections in the elderly (Journal of Lueukocyte Biology, 2008; 84:900-914; Immunological Reviews, 2005; 205:269-284).

Micro-importance

Some strains of probiotics, beneficial microorganisms, can replace the healthy bacteria in our bodies, enhance immune functioning, improve colonic integrity and help protect us against microorganisms that could cause disease, according to the National Institutes of Health National Center for Complementary and Alternative Medicine, Bethesda, MD.

For a probiotic to be effective, it must survive the manufacturing process, as well as shipping and storage. However, there is some debate about whether or not probiotics must adhere to mucosal cells in order to be effective. Probiotics pass through the small intestine, and those that survive intestinal transit establish themselves for a short period of time in the large intestine (American Journal of Clinical Nutrition, 1991; 73(2):399S-405S).

Because only a certain percentage of probiotics survive their trip through the intestines, and they may or may not adhere to intestinal mucosal cells, supplemental probiotics need to be taken continuously for a sustained effect, making frequently consumed foods and beverages the most effective candidates for probiotic fortification. Each species and strain of probiotics is different, and if immune health is the objective, it is critical to choose a species and strain that is backed by sound clinical research.

Prebiotics such as fructooligosaccharides and oliogosaccharides also benefit the immune system by stimulating the production of nonpathogenic intestinal microflora (Journal of Physiology and Biochemistry, 2009; 65:315-328).

Polysaccharide balance

With the popularity of gluten-free diets, one may think that going gluten-free has no disadvantages. However, two studies examining gluten-free diets in healthy individuals found that this diet resulted in a decrease in healthy gut bacteria and an increase in unhealthy gut bacteria (Gut Microbes, 2010; 1:135-137; British Journal of Nutrition, 2009; 102:1,154-1,160).

Gluten-containing foods may affect immune function because they are rich in polysaccharides. Both animal and human studies show that several polysaccharides, particularly glucans, modulate the immune system. Though polysaccharides show promise for immune functioning, scientists havent determined how polysaccharides are best consumedcontinuously or intermittently, and if continuous consumption always results in increased tolerance (Nutrition Journal, 2010; 9:54).

Dairy for health

Dairy colostrum, the milk produced by the mom within the first few days after giving birth, is packed with immune-boosting compounds called immunoglobulins (British Journal of Nutrition, 2000; 84:S75-S80). Food scientists have found ways to produce milk with elevated concentrations of immunoglobulins, notably IgA, which is one of the most common and stable immunoglobulins in milk. Milk and dairy products with higher levels of immune components may be used as a prophylactic or therapeutic treatment to boost immune-system functioning (Journal of Animal Science, 2009; 87:3-9).

Several peptides and proteins found in milk have potential antibacterial, antifungal or antiviral properties. Whey protein is rich in immunoglobulins, as well as both cysteine and methionine, two amino acids that promote glutathione production. Glutathione enhances immune-system function by protecting cells from oxidative stress. Cysteine is the rate-limiting amino acid in the production of glutathione, and whey-protein concentrate and whey-protein isolate contain at least four times the concentration of cysteine as other high-quality proteins (Biomedicine & Pharmacotherapy, 2003; 57:145-155; Journal of Sports Science and Medicine, 2004; 3(2):60-63).

Boosting glutamine

Glutamine, though typically a conditionally essential amino acid, becomes essential during times of physical stress and during severe illness, because the consumption rate exceeds the bodys supply. While recovering from illness or injury, or during extreme training in athletics, supplemental glutamine can help keep the bodys immune system running strong (Current Opinions in Clinical Nutrition and Metabolic Care, 2010; 13:58-64; The Proceedings of the Nutrition Society, 2009; 68:261-268).

With several naturally occurring immune-boosting compounds in food, as well as formulated ingredients, companies have many options for developing foods that keep the immune system running strong.

Marie Spano, M.S., R.D., CSCS, is a nutrition communications expert whose work has appeared in popular press magazines, e-zines and nutrition-industry trade publications. She has been an expert guest on NBC, ABC and CBS affiliates on the East Coast. For more information, visit mariespano.com.