Consumers are seeking products that help maintain a strong immune system. According to a 2008 International Food Information Council survey, 87% of Americans are currently consuming or interested in foods and beverages that improve immune system function. Mintel, a leading market research company, found that 69% of consumers polled said they would like products that help maintain a strong immune system. This places foods marketed to highlight such benefits in a significant category, with growth expected to continue.
There are no approved or defined health or disease prevention claims for nutrients, dietary components or herbal substances related to immune function, so product labeling statements in this area tend to be primarily structure-function claims. In its 2008 “Consumers and Nutritional Labeling” global report, Nielsen listed probiotic claims among those of highest growth in the previous year.
Healthy Benefits from Whole Foods
Discoveries continue about the goodness of foods in their whole, natural form. Along with their traditionally known ability to prevent urinary tract infections, emerging research suggests that cranberries derive immunity benefits from their anti-adhesion mechanism. Unique A-linked compounds (called proanthocyanidins) prevent bacteria from adhering to cell walls, removing the potential for infection. (See sidebar “Myth or Truth: Cranberry Juice.”)
By eating them whole, almonds can potentially boost healthy immune function, as the skins are associated with benefits, according to results of a study presented at the 109th General Meeting of the American Society for Microbiology. Almond skins may protect against viral infection and reduce inflammation for a helpful impact on the treatment of infectious disease, through an immune response and by acting as unique, novel antiviral agents.
Yogurt, required by law to be made with the lactic acid-producing bacteria Lactobacillus bulgaricus and Streptococcus thermophilus, has a cultured advantage for immunity. Lactobacillus acidophilus, L. casei and Bifidobacterium lactis, as well as a number of other microbial strains, are optional additions in some brands, such as Stonyfield Farms’ “Natural Balance.” Research, generally with individual specific microbial strains, supports the ability of specific probiotics to help strengthen the body’s natural defenses by providing a regular source of “friendly” bacteria to the intestinal tract and increasing production of antibodies and other immune cells.
How probiotics enhance immunity is under much investigation. Wikipedia lists possible mechanisms to protect against pathogens, such as competitive inhibition and/or increasing the number or proportion of the immune system’s IgA-producing plasma cells, phagocytosis, T lymphocytes and natural killer cells. An online review titled, “Proposed Model: Mechanisms of Immunomodulation Induced by Probiotic Bacteria” (Maldonado Galdeano, CM, et al. 2007. Clin Vaccine Immunol. 14:485-92), can be seen at http://cvi.asm.org/cgi/content/full/14/5/485.
Because some yogurt products are heat-treated after fermentation, which kills most of their beneficial active cultures, the National Yogurt Association (NYA), a national non-profit trade organization whose purpose is to sponsor health and medical research for yogurt, has established a special Live & Active Cultures seal to help consumers identify those yogurt products that contain the living organisms Lactobacillus bulgaricus and Streptococcus thermophilus, which convert pasteurized milk to yogurt during fermentation. The NYA seal is available to qualified producers of live and active culture, refrigerated and frozen yogurt, for use on product labels and in advertising and promotional materials. In order to place the NYA seal on a product’s label or to use it in advertising, a producer or distributor must have a state or USDA-certified independent laboratory perform tests on representative samples of its product and certify that the samples meet the criteria adopted by the NYA board of directors for live and active cultures.
Extracts and Other Components
A variety of other foods and components, which are commercially available as dietary supplements, have built a reputation for potential immunity benefits.
Shiitake mushrooms are a source of beta-glucans produced by fermentation that contain high-molecular-weight polysaccharides, which appear to improve immune function defense by fighting off infection. There has also been much interest in a mushroom extract, active hexose correlated compound (AHCC), which is an oligosaccharide believed to have the ability to strengthen the immune system. The AHCC Research Association’s website can be seen at www.ahccresearch.com.
Well-known for fighting colds and reducing the length and severity of cold symptoms, Echinacea appears to boost the immune system and help prevent infections. Both the root and the herb of the plant are used in teas, extracts and juices, and its effectiveness seems to be the greatest when taken at the first signs of an illness.
Containing the highest concentration of flavonoids among commonly consumed berries, black elderberries are rich in immune-boosting anthocyanins, and their extract is believed to contain an antiviral agent called “antivirin,” which ultimately inhibits cold and flu viruses from progressing by destroying their ability to infect. Elderberry extract also activates the healthy immune system by a strengthened role in the inflammatory process.
Oasis Health Break Immuniforce, a blend of blackcurrants and elderberries, is said to be the first juice in North America to contain an ingredient whose biological effect on the immune system has been scientifically proven. “This product represents a very interesting option for those wishing to maintain a healthy immune system,” explains Solange Doré, vice president, research and development. It contains a natural ingredient derived from yeast that activates key immune cells that defend the human body against a multitude of health threats. Clinical studies show this ingredient has a positive effect on overall health and protects against the effects of stress on physical and psychological well-being.
Vitamin C and zinc improve symptoms and shorten the duration of respiratory tract infections, including the common cold, and improve the outcome of pneumonia, malaria and diarrhea infections, especially in children. New Juicy Juice® Immunity Fruit Juice Beverage contains vitamin C and zinc to help support the immune system, plus prebiotic fiber for digestive health.
The Pre- and “Pro-tection” of It
The value of yogurt is an example of how digestive health has strong links with immunity, since about 70% of the human immune system is located in the digestive tract and about 60-80% of immune cells are associated with the gut.
Prebiotics are non-digestible food components or ingredients that improve health by stimulating the growth activity of “good” digestive tract bacteria and preventing the colonization of “bad” bacteria. In certain amounts, probiotics (live microorganisms that impart a health benefit) enhance immune function by competing with invading infections, correcting any abnormal ratio of beneficial vs. “bad” bacteria, keeping the digestive tract’s bacterial environment in a normal, healthy balance.
Clinical effectiveness of specific strains of probiotics have been shown in the prevention or treatment of certain gastrointestinal disorders, respiratory infections, allergic conditions, AIDS and urinary tract infections. Pre- and probiotic mixtures could also become a viable means of countering allergies--pre- and probiotic mixtures may lower allergic response to cows’ milk.
Because friendly bacteria in the digestive system improve how vitamins, nutrients and synergistic enabling co-factors are absorbed, overall immunity is boosted when gut health is preserved; conversely, poor gut health is more likely to predispose to a virus or other chronic illness. Smaller, emerging studies suggest that gluten-free diets could compromise optimal gut health, as lesser “good” bacteria activity is seen in the gut, when gluten is consistently avoided. An association between suppressed immune health in the mother was recently identified as a possible contributing factor for the risk of autism in a newborn.
The Journal of Food Science recently published a study revealing that encapsulating probiotics in various forms of coating materials, including alginate, guar gum, xanthan gum, locust bean gum and carrageenan gum, may help survival in the gastrointestinal tract. Encapsulated bacteria survived better than the control group, strongly suggesting that microencapsulation may prove to be an important method of improving the viability of probiotic bacteria in acidic food products; this would allow the delivery of viable bacteria to the host’s gastrointestinal tract, while protecting probiotic cells from harsh environmental conditions.
Probiotic food products are growing beyond the traditional yogurt and fermented dairy product sector. Max Muscle recently introduced the first-ever probiotics protein bar. Considering the demands placed on the digestive systems of athletes and others who supplement with protein, it is imperative that the digestive system function optimally to properly utilize the added protein, and research shows probiotics help with protein digestion and assimilation.
A range of food manufacturers anticipate offering consumers a greater variety of probiotic-enhanced food products. These items include nutrition bars, frozen yogurt and muffins. NS
Lauren Swann, MS, RD, LDN, is a freelance writer and president of Concept Nutrition Inc. (Bensalem, Pa.), which offers consulting services specializing in food labeling, nutrient analyses, marketing communications and cultural dietary practices. She can be reached at 215-639-1203, LS@FoodFactsWork.com or www.FoodFactsWork.com.
Myth or Truth: Cranberry Juice
Cranberry juice has long been consumed for its urinary tract benefits. While “old wives’ tales” often fall by the wayside, cranberries’ benefits are so well-documented that even a review in the conservative Cochrane Database (a collection of systematic reviews and meta-analyses of high-quality medical research) gives cranberries the “thumbs up.” (Jepson, RG, Craig, JC. 2008. Cochrane Database Syst Rev. Jan 23;
Rather than enhancing the immune system, defined in Merriam-Webster Online as “the bodily system that protects the body from foreign substances, cells and tissues, by producing the immune response,” researchers believe that cranberries’ proanthocyanidins inhibit bacterial adhesion to bodily tissues, an activity possibly related to the reduction of microbial hydrophobicity
-- Claudia D. O’Donnell, Chief Editor
Fruits, Vegetables and Immunity
At least one research study shows fruit and vegetable consumption positively impacts immunity, as well as antioxidant levels in the blood serum (Nantz, MP, et al. 2006. J Nutr. 136:2606-10). In a double-blind, randomized, placebo-controlled study, 59 participants received an encapsulated fruit and vegetable juice powder concentrate (FVJC). After 77 days, the FVJC group experienced a 30% increase in circulating gamma delta-T cells and a 40% reduction in DNA damage in lymphocytes. The study’s abstract also reports, “Plasma levels of vitamin C and of beta-carotene, lycopene and lutein increased significantly from baseline in the FVJC group, as did plasma oxygen radical absorptive capacity (50%).”
Opportunities are not lost on the food industry. For example, Chiquita’s Fresh Express Farms website notes its products contain, “Phytonutrients that have health-promoting properties, such as helping boost immunity and providing antioxidant protection.” Besides salads, Mintel’s GNPD reports this description also accompanies Chiquita’s recently introduced Apple Grape Bites and Pineapple Bites.
-- Claudia D. O’Donnell, Chief Editor