Can food be a cause of Rheumatoid Arthritis?

G enetics, pathogenic organisms, food compo­nents, and intestinal permeability (leaky gut) can all play a complex role in the development of rheumatoid arthritis. One hypothesis, which was presented in a review article published by the British Journal of Nutrition (BJN) in 2000', explains that food protein sequences, just like proteins from pathogenic organisms, can activate autoim­mune reactions in genetically susceptible people. Additionally, if the gut isn't "leaky", as described in last issue's article, then these proteins don't cross the intestinal barrier and initiate the reaction. This review article re­flects the extensive work of a research team at Colorado State University, Fort Collins, CO, of which I was honored to be a par­ticipant. I co-authored a review article entitled, "Modulation of Immune Func­tion by Dietary Lectins in Rheumatoid Arthritis," published in the BJN. The Molecular Mimicry Theory The review article delves into pin­pointing immune activation in rheuma­toid arthritis. The theory that non-hu­man protein sequences (food, bacte­ria, viruses) can be similar enough to cause the human body to initiate an attack on itself is referred to as "mo­lecular mimicry". The theory is gaining credence as a viable theory, as evi­denced by the recent appearance in the New England Journal of Medicine of an article entitled, "Mecha­nisms of Disease: Molecular Mimicry and Autoimmunity'V The NEJM article ponders how foreign antigens, such as viruses, can activate immune responses (in genetically susceptible people) against human tissue, by exhibiting similarities with hu­man protein. In our ft/Af article, however, we ponder how actual dietary constituents found in common foods can trigger the molecular mimicry process and result in the attack on self tissue. Genetics, of course, will play a major role in how an individual manages an immune response, and will determine, to some ex­tent, how an individual is going to respond to simple common foods. One of the take-home messages is that, if you combine the genetic susceptibility with the right dietary antigens (and possi­bly viruses which interact in the process), and then you throw in a leaky gut, the increased intestinal permeability can allow for the translocation of these antigens into the circulation where they can activate autoimmune diseases, such as rheuma­toid arthritis. In other words, a leaky gut can be a setup for autoimmune disease. In the molecular mimicry model, when these sub- stances activate the immune system (in genetically sus­ceptible people), antibodies arc formed to attack the foreign substances, or antigens. The problem is that the antibodies also recognize the protein sequences in the self or human tissue that are similar to the foreign protein in the bacteria or vims (or food). This is called cross reactivity. As an example of molecular mimicry and cross reactivity, the NEJM article cites the case of MS. "The host's (virus's) antiviral immune response cross-reacts with central nervous system self-antigens, such as myelin basic protein (MBP), leading to dcmyclination."- Molecular Mimicry and Rheumatoid Arthritis There is ample evidence that the same kind of molecular mimicry sus­pected in MS could be at play in RA, with the major difference being the self tissue that gets attacked. Whereas in MS it is myelin basic protein, in RA it is suspected to be collagen tissue. Not only can certain undigested food par­ticles cause a problem by mimicking human self-proteins, such as collagen, but other substances found in some foods, such as lectins, can increase intestinal permeability and allow these mimicking proteins into systemic circulation. Mimicking proteins include bovine serum albumin (BSA) from cow's milk, which contains a protein se­quence similar to human collagen, and glycine-rich protein (found in grains and legumes), which contains a protein sequence simi­lar to connective tissue. Dietary Lectins Particular lectins to watch are wheat germ agglutinin (WGA) from wheat, phytohaemagglutinin (PHA) from kidney beans, and the peanut lectin (PNA) from peanuts. Other lectin-containing foods include lentils, peas, and jack beans. Lectin activity has also been demonstrated in rye, barley, oats, and maize,3 and even rice.4 This is not meant to alarm people about eating these types of foods. Remember one of the key points of this article: People with hereditary predispositions for autoimmune disease are the ones who are particularly susceptible to food interac- tions with the immune system. This ar­ticle is also not meant to imply that every­one who exhibits rheumatoid arthritis re­acts to food. It is just presenting a viable scientific theory for why SOME people who experience rheumatoid arthritis may have it. The Leaky Gut Factor One of the most important factors in this theory is the leaky gut, because it is the intestinal permeability that allows the for­eign antigens into systemic circulation. We sometimes forget that the gut does more than digest our food. It is an im­mune barrier that protects us from for­eign attack. Immune protection in the gut is sup­plied by a number of mechanisms includ­ing: The intestinal mucosa (physical bar­ rier) Intestinal secretions (such as secretory IgA antibodies) Intramural lymphocytes (white blood cells) There arc laboratory tests that can be done for leaky gut, which include the lactulose-mannitol test. This test mea­sures the excretion of these two sugars into urine, and the ratio gives a good idea of the degree of leakiness. However, many people support the leaky gut with nutri­tion, and are satisfied with the results with­out sending urine samples away to the lab. Lab tests can also verify low secre­tory IgA antibody levels; but then, again, zinc is known to fortify the intestinal bar­rier and increase the level of these protec­tive factors. Zinc "enhances immuno-logic mechanisms for the clearance of in­fection, including cellular immunity and higher levels of secretory antibodies/'5. Helpful Nutrition Basically, the gut is an immune barrier; and, when it fails to do its job, autoim­mune reactions can develop. It is clearly important to build and strengthen that im­mune barrier. This is why one whole ar­ticle was devoted to the leaky gut (last issue). As a review, following are some of the nutrients you need to strengthen the leaky gut: Glutamine is the main fuel that the in­testinal cells need for maintenance and repair. Vitamins C and E, lipoic acid, zinc and ginkgo biloba are all antioxidants, which protect the lining from free radical dam­age. DGL (deglycyrrhizinated licorice) in­creases the integrity of the mucosal cells.6 NAG (N-acetyl glucosamine) helps heal extracellular tissue and decreases the bind­ing of some lectins. NAG also increases the quantity and quality of mucus.7 It is even listed as an antiarthritic in the Merck index.'1 Probiotics counteract bad bacteria and help to fortify the integrity of the gut. Ad­ditionally, "Patients with RA have also been shown to maintain a high frequency of small-intestinal bacterial overgrowth."9 The Importance of Hydrochloric Acid and Digestive Enzymes As we have seen, undigested food par­ticles that cross a leaky gut can become antigens that can stimulate the immune system. Healing a leaky gut is part of the answer, but another key is addressing the incomplete digestion of the food particles in question. Amino acids arc not anti-genic; they are only longer protein se­quences that are antigenic, and they can only activate the immune system when they have not been properly broken down. This happens sometimes due to a lack of hydrochloric acid and pancreatic enzymes. This is described in the arthritis article... "Clearly implicit in this model is the ability of intracpithclial pathogens and intact pro­teins to escape enzymatic digestion and to cross the gastrointestinal barrier and enter peripheral circulation." In summary, if you combine genetic sus­ceptibility with the right dietary antigens and then you throw in a leaky gut as an­other factor, it could possibly activate au­toimmune diseases. The beneficial nutri­ents mentioned here offer support for this condition. | Dr. Toohey received her Ph.D. in nutrition from Colorado State University in Ft. Collins, CO. She has lectured to chiropractors and other health professionals across the country and also in Canada and Europe. She has been invited by the Canadian MS Society to he a guest speaker at their annual convention in Vancouver (Nov. I6'h). Various lecture engagements have included speaking /or the International Col­lege of Applied Kiiwsiology, the United Chiro­practors of New Mexico, and the Florida Chiro­practic Association. You may reach Dr. Toohey by e-mail at See page 50 for References NUTRITION-Pg 18 Can Food be a Cause for Reumatold Arthritis? by Lynn Toohey Ph.D. (Ordain L., Toohey L, Smith MJ and Mickey MS. Modulation of Immune Function by Dietary I.ectins in Rheumatoid Arthritis. Brit­ ish Journal of Nutrition 2000;X3:(>00-000. Albert LJ & Inman RD, 2000:341 (27):206K-2074. Licncr, The Lectins. .Orlando. FL, Academic Press. 1986:527-552. Tsuda, M. Purification and characterization of a lectin from rice bran. J Biochem. 1979;86:1451-1461. NE.IM Sept. 28, 1995. 333:839-844.p. 842. Glick I.. Lancet ii:XI7. 1982. J llelminthol. 1993:67(3): I 79-88. Merck Index. 11th ed. 19X9 Merck and Co.. Inc. Railway. N.I p. 4353. llcnriksson. el ill. Annals of the Rheumatic Diseases 1993:52:503-510.