Food as it relates to allergies involves more than avoiding peanuts. There are food ingredients believed to help allay the symptoms of allergies and asthma. For example, bee pollen is promoted as a remedy for seasonal allergies and the B vitamins thiamine and riboflavin have been touted as helping alleviate allergic reactions to mosquito bites.
The food-arthritis link has been investigated for centuries. For example, some researchers have suggested a causality in compounds called solanines, found in the nightshade family of plants, and includes potatoes, peppers, eggplant and tomatoes.
The FDA has not signed off on most foods promoted as disease- or symptom-ameliorating, and for a good reason: Many of the links between food and specific conditions are tenuous at best. But all maladies involve immunity, and immunity is a rapidly growing part of wellness foods, involving physical and mental function.
An Integrated System
The immune system is a highly integrated, complex web of specific and nonspecific branches. Nonspecific ("innate") immunity is provided by a system of natural protective barriers to invading microorganisms. The skin and mucus membranes act as physical barriers. Friendly gut bacteria compete with invaders. Stomach acids and chemicals in the intestines can rupture bacterial cells and mark them for destruction by the body, and inflammation dilates the blood vessels and recruits other protective factors.
|Cherrybrook Farms - both the company and its products - came about because one of its founders developed food allergies as an adult and had difficulty finding baking mixes without dairy, eggs and nuts.
Complementing the innate system is specific ("acquired") immunity. This is the part of the immune system that can recognize and eliminate a virtually endless diversity of foreign proteins. This function is carried out by two types of cells that generate specific responses: lymphocytes and antigen-presenting cells.
Lymphocytes are either B-cells or T-cells. B-cells produce antibodies (immunoglobulins) to invading proteins. Once sensitized, they'll remember the invader forever. T-cells can be either Cytotoxic Ts, which kill infected cells, or Helper Ts. Helper Ts produce chemicals called cytokines that coordinate the intricate actions of cell-based immunity.
Avoiding the Triggers
The most basic relationship between diet and immunity people face is avoiding specific foods that trigger allergies. Food allergies constitute a topic unto themselves, but a little background helps us understand how foods that help alleviate allergy symptoms might work.
Although most people have experienced a reaction to a food, it's estimated that 8 percent of children age 6 years or younger, and 1 to 2 percent of adults, suffer from a true food allergy. Food allergies kill approximately 150 Americans (usually children) each year. One in three people alter their own or a family member's diet because of a suspected food allergy.
An allergy is an exaggerated immune response to a common protein, food-based or otherwise. That response - an outpouring of histamine and other inflammatory proteins - can result in anything from gastrointestinal distress, nausea, and vomiting to rashes, swelling and bronchospasms that make breathing difficult. Symptoms can be mild, or turn fatal as blood pressure drops and swelling chokes off airways.
Eight types of food account for over 90 percent of all food allergies: dairy products, soy, shellfish, wheat, tree nuts, peanuts and egg whites. Since it's often difficult to find common foods without these proteins, many food manufacturers are finding a market in providing foods free of these common triggers.
Pacific Foods helps to fill this niche with an extensive line of organic wheat-, gluten- and casein-free soups, milks and broths. The company is now offers ready-prepared meals, too. Entire companies, such as Cherrybrook Kitchen (www.cherrybrookkitchen.com), Lawrence, Mass., began as someone's personal crusade to avoid food allergies. "My wife Patsy and I started Cherrybrook Kitchen after she developed food allergies as an adult. Patsy was suddenly faced with the difficult task of learning how to eat and cook without dairy, eggs or nuts. A self-professed chocoholic, she realized early on that there were no baking mixes on the market that could satisfy her sweet tooth and meet her allergy needs," explains Chip Rosenberg, the company's CEO and co-founder.
Responding to Inflammatory Response
The inflammatory reaction is an important interface between diet and immunity. Much of the discomfort and potentially severe complications that result from allergies is generated by our own reaction to the allergen.
The question of how to tame the defensive reaction has stimulated much nutrition research. One class of ingredients seeing an explosion of interest is omega-3 fatty acids.
The fats we eat can influence the intricate signals by which immune cells communicate. The most abundant fatty acid in cell membranes is arachidonic acid. We get it from foods like meat and eggs or indirectly by modifying linoleic acid, an omega-6 fatty acid found mostly in vegetable oils.
Arachidonic acid is converted to a group of compounds (collectively known as ecosanoids) that affect immunity, influencing fever regulation, vascular permeability, vasodilation, the proliferation of natural killer cells and lymphocytes and the production of cytokines. The result of all this action is to promote inflammation. In theory, by displacing some of the arachidonic acid in the immune cells, different ecosanoids are produced whose actions are anti-inflammatory.
According to Doug Bibus, a researcher at the Univ. of Minnesota's Hormel Institute and scientific advisor to the Coromega Co. (www.coromega.com), Carlsbad, Calif., an important determinant of immune response is the ratio of omega-6 to omega-3 fatty acids in our diet. We consume a great deal of omega-6-rich vegetable oils that were scarce in the human diet only a few generations ago. The result is a ratio of omega-6 to omega-3 that can be as high as 25/1. Bibus describes this as "adding wood to the fire of inflammation," viewing a ratio of 5/1 to be a more healthy balance.
Arthritis, Asthma and Fish Oil
The main omega-3 fatty acids in fish are EPA and DHA. In clinical studies, rheumatoid arthritis sufferers reported some relief from morning stiffness following supplementation of their diets with fish oil. Also, in a recent prospective study of over 330 children, increased incidence of asthma was linked with a higher ratio of omega-6 to omega-3 fatty acids in their diets.
In yet another study, a high ratio of omega-6 to omega-3 at birth was associated with the children developing eczema at 18 to 30 months of age, and the onset of wheezing at 30 to 42 months of age. The suggestion was that - at least in some children - more omega-3 fatty acids in the diet may provide some protection against symptoms of asthma and associated conditions.
There is still much to be learned, but good reason exists to suggest that shifting the balance of fatty acids to a lower ratio of omega-6 to omega-3 ratio by eating more omega-3 rich foods such as greens, fish, flax and walnuts or omega-3-enriched products may lessen an overreactive immune response.
Algae also are an important source of omega-3s, but algae, seaweed and other ocean plants do not take up much space on the American plate. Earthrise Nutritionals (www.earthrise.com), Irvine, Calif., the world's leading producer of spirulina and spirulina-based products, is on a mission to fill the algae nutrition gap by farming spirulina for use in meal replacements, beverages and healthy snack formulations.
In addition to omega-3, spirulina is rich in antioxidants and vitamins E, C, B-complex, beta-carotene and carotenoids, and in the trace minerals zinc, copper and iron. All of these micronutrients are necessary for immune system health.
Spirulina has been shown to help reduce levels of cytokines which indicate increased probability of cytokine-mediated hypersensitivity, which is one of the main factors responsible for allergic reactions.
Another type of nutraceutical compound showing promise for combating symptoms of arthritis is the antioxidant polyphenolic group. The primary polyphenol in green tea, epigallocatechin gallate (EGGC), is a potent anti-inflammatory. Taiyo International Inc. (www.taiyointernational.com), Minneapolis, has been supplying green tea to beverage manufacturers for decades. The company pioneered research into naturally occurring functional food and beverage ingredients that aid the body's ability to protect and manage health.
|Inulin is a prebiotic that can be incorporated into a wide range of food products, such as baked goods, confections, dairy products and beverages.
In the last 15 years asthma in the United States jumped 50 percent among preschool-aged children, and 74 percent among school-aged children. While there's no indisputable evidence that this increase is related to diet, it can be no coincidence that it closely matches the epidemic of obesity and type II diabetes, diseases that are unquestionably linked to the modern low-nutrient/high calorie diet.
One theory behind the increased prevalence of asthma among developed nations is people reduced intake of antioxidants, leaving the lungs more susceptible to oxidative damage.
Another fundamental link between diet and immunity is the integrity of the intestinal lining, which protects us from ingested pathogenic bacteria. An important part of innate immunity is the stimulation of friendly bacteria - probiotics - that reside in the intestines.
Probiotic bacteria thrive on carbohydrates that escape digestion. Dietary prebiotic compounds (for example, inulin and oligofructose, which are made up of chains of fructose that cannot be digested, or resistant starch, the portion of starch that escapes starch-digesting enzymes) may thus be beneficial.
Friendly lactic acid-producing bacteria convert these compounds into short-chain fatty acids and use them for energy. Recent studies in animals suggest that inulin and oligofructose may also stimulate the proliferation of natural killer cells and the production of immunoglobulin A, the gut-associated antibody that guards against invading bacteria in response to the invader.
Orafti Active Food Ingredients (www.orafti.com), Malvern, Pa., producers of inulin and oligofructose, point to studies linking consumption of those polysaccharides to lower incidence of fever, fewer doctor visits and fewer sick days from daycare for infants and children as evidence for the benefit of prebiotics. According to the company, the benefit for formulators is that inulin and oligofructose can be incorporated into a wide range of food products, such as baked goods, confections, dairy products and beverages.
"Synbiotic" is the term for the combination of probiotics and prebiotics that feed them, a combination that may be even more effective than adding one or the other. On the horizon are new probiotic strains selected specifically as synbiotic combinations with resistant starch.
The Original Probiotic
One of the oldest known probiotic foods is yogurt. Its custard-like texture, tart taste and probiotic ability stem from characteristic bacteria that ferment the milk and convert lactose (milk sugar) into lactic acid. Lactobacillus bulgaricus is the main strain of bacteria in yogurt, but Streptococcus thermophilus, Lactobacillus casei, Lactobacillus acidophilus and Bifidobacteria lactis may also be in yogurt and have similar health-promoting properties.
Stonyfield Farm (www.stonyfield.com) Londonderry, N.H., has furthered enhancing the basic probiotic profile of yogurt further by adding another type of lactobacillus, reuteri (as well as inulin) to its formulae. In a January, 2005 study in several Israeli daycare centers, L. reuteri proved to be more effective than B. lactis when comparing days with fever, fewer doctor visits, diarrhea episodes, childcare absences and antibiotic prescriptions in subjects.
Protein and Minerals
Whole-body health is intricately linked to whole-body nutritional balance. For example, sufficient dietary protein is critical to immune function, but excessive protein may have a detrimental effect. A number of essential vitamins and minerals, such as vitamin A, beta-carotene, folic acid, vitamin B12, vitamin C, riboflavin, iron, zinc and selenium also have important immune-related functions.
Vitamin A has been called the anti-infective vitamin because of the close association between severe vitamin A deficiency and increased infection-related illness and death. This may relate to the necessary of vitamin A for the maintenance of healthy levels of circulating T cells in children. Even a mild deficiency may increase the risk of infection.
Vitamin A plays a crucial role in the health and normal functioning of the skin and mucosal cells that line the airways, digestive tract, and urinary tract, limiting the colonization of pathogenic microbes. Both vitamin E and vitamin B6 are critical to immune health, especially as we age.
|Enhanced beverages are increasingly becoming destinations for immune-support nutrients. Glaceau, for example, offers "Defense," a raspberry-apple-flavored water fortified with zinc, vitamin C, and four of the B vitamins.
Research conducted over the past 20 years has demonstrated that large doses of vitamin C do not significantly reduce the incidence of the common cold, supplemental vitamin C may lessen severity and duration of colds by lowering histamine release.
Zinc has great scientific support for its abilities to reduce the severity and duration of colds, too. (For more on zinc, see "Heavy Metal," Feb. 2006) The vital mineral plays an indisputably central role in immune health, and zinc deficiency increases susceptibility to a variety of pathogens. It's also a nutrient most Americans are lacking in their diet. In addition, zinc functions as an antioxidant, stabilizing membranes and protecting the integrity of the skin as a barrier, and assuring the normal development of immune cells.
Another trace mineral, selenium, helps regulate the production of cytokines by T cells, which in turn control the immune response. This may be why selenium deficiency has been linked with impaired immune function. Selenium supplementation has been shown to enhance the production of antibodies in response to foreign antigens.
Copper is important to the development and maintenance of immune function through an as yet unknown mechanism. Abnormally low white blood cell count is a clinical sign of copper deficiency in humans.
Drink to Your Health
Beverages have taken a leading role in the pro-immunity sphere. Tropicana Products Inc., Bradenton, Fla., has enjoyed strong sales from its "Tropicana Pure Premium Immunity Defense" orange juice, enhanced with vitamins C and E, as well as selenium and folate.
With the motto "hydrate responsibly," Glaceau (www.glaceau.com), Whitestone, N.Y., is a pioneer of enhanced water beverages, with several lines of waters supplemented with B vitamins, vitamins C and E, zinc, selenium, beta-carotene, and other antioxidants in combination with fruit and plant extracts. Under the company's Vitaminwater category, Glaceau features "Defense," a raspberry-apple-flavored water fortified with zinc, vitamin C, and four of the B vitamins.
Such anti-inflammation, anti-allergy and pro-immune benefits to foods and beverages are becoming increasingly important to consumers. From beverages and bars to cereals and snacks, the inclusion of proactive and protective components is only increasing. Even breath mints are taking the opportunity to protect us against more than social ills. Dyna-Tabs Products (www.dynatabs.com), Brooklyn, N.Y., includes citrus-flavored, vitamin C-laced "Immune Health Support" to its line of dietary supplement-enhanced breath strips.
Immune protection is like a chain of barriers to disease. But this chain is only as good as its weakest link. "Boosting" the immune system is a whole body event that is intimately linked to balanced, healthy diet.