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Inflammatory Bowel Disease: Nutritional Considerations

Nutritional factors may be important in IBD. The factors currently believed to help prevent or treat IBD are as follows:  

  • Breast–feeding: A large study found that the risk for ulcerative colitis was 25 percent lower and the risk for Crohn’s disease 35 percent lower in individuals who were breast–fed. Breast–feeding may protect against IBD in several ways: by protecting against gastrointestinal infection during infancy, by stimulating the early development of the gastrointestinal tract, and by delaying exposure to cow’s milk.
  • A Western dietary pattern: Western diets that are relatively high in meat, dairy products, and sugar, and low in fiber and other plant constituents have been associated with a higher risk of IBD. In contrast, traditional diets in other regions of the world are more plant–based, including higher amounts of vegetables, fruits, nuts, and seeds. It is difficult to identify specific aspects of the diet that are responsible for this pattern. Possible candidates that have been studied will be discussed below. However, it may be that interventions to reduce risk need to address the overall dietary pattern, rather than its components.
  • Animal protein: Dietary data from Japan suggest that the westernization of traditional Asian diets is associated with increased risk for IBD. A study looked at the difference in typical Japanese dietary intake from 1966 to 1985. When the incidence of Crohn’s disease and the daily intake of various dietary components were evaluated, animal protein intake emerged as the strongest independent risk factor.

    Animal protein contributes significantly to the amount of a toxin called hydrogen sulfide in the colon, which may increase disease activity in ulcerative colitis. Additionally, hydrogen sulfide may also interfere with the actions of butyrate, an important anti–inflammatory molecule in the colon.

    Among patients with ulcerative colitis, meat intake significantly increases the rate of relapse. Red meat and processed meat intake increases the rate of relapse more than five–fold. Conversely, a pilot study that restricted animal protein and other forms of sulfur resulted in a complete absence of IBD relapse. However, further studies are needed to confirm these effects.

    In contrast, diets that primarily provide vegetable sources of protein result in lower amounts of hydrogen sulfide in the colon and have been associated with a decreased risk of Crohn’s disease.
  • Dairy products: Individuals with IBD are often sensitive to cow’s milk. Further, those with IBD and documented cow’s milk allergy have been shown to develop ulcerative colitis at an earlier age than did people with this disease who were free of milk allergy. Patients with IBD often have antibodies to cow’s milk protein, and these correlate with disease activity in Crohn’s disease. Studies also indicate that cow’s milk increases both intestinal permeability and production of proinflammatory cytokines, both of which are involved in IBD.

    Preliminary research findings indicate that allergies to foods other than dairy products might be involved in IBD, but further study is required before hypoallergenic diets are established as an effective IBD treatment. 

    Some evidence suggests that a milk–borne infection may play a role in the development of Crohn’s disease. Bacteria called Mycobacteriaum avium, which are commonly found in milk products, are known to survive pasteurization and cause a Crohn’s disease–like illness (Johne’s disease) in dairy cows. Interestingly, these bacteria have been found with far greater frequency in patients with Crohn’s disease than in those with ulcerative colitis or healthy people. However, the pathogen has not yet been proven to be a causative agent in Crohn’s disease, and the benefit of treating it with antibiotics has not been established.
  • A high–fat diet: Diets that are high in fat, particularly animal fat, and cholesterol have been shown to be associated with significant increases in the risk for IBD. This may be due to increases in inflammation caused by certain fats, called omega–6 fats. These are primarily found in animal products and some vegetable oils (e.g., corn, safflower, and sunflower oil).

    The intake of foods containing partially hydrogenated fats, including fast foods, fried foods, margarine, baked goods, and packaged foods, is also associated with IBD risk. In countries where margarine consumption has increased, an increase in Crohn’s disease followed. Persons eating fast foods at least twice per week had three times the risk for Crohn's disease and four times the risk for ulcerative colitis, compared with those who avoided these foods.
  • A low–fiber diet: Compared with persons consuming small amounts of fiber, those eating 15 grams or more per day had only half the risk for developing Crohn’s disease. In particular, fiber intake from fruit appears more strongly associated with reduced risk of IBD. In addition, individuals eating high–fiber diets were more likely to remain in remission, or had significantly fewer and shorter hospitalizations and required less intestinal surgery, than a control group of patients who did not have a change in their fiber intake.

    Most high–fiber foods are also high in naturally occurring antioxidant vitamins and minerals, as well as protective plant compounds, called carotenoids and flavonoids. These substances help to limit oxidative stress, a condition found in individuals with IBD as a result of inflammation in the colon.
  • High sugar intake: Studies have consistently found an association between higher intakes of sugars and the development of IBD. However, these associations may merely reflect lifestyle patterns common in populations with IBD. A biological mechanism has not been established for sugar’s effect in IBD, and larger clinical trials have not documented significant benefits of a diet low in refined carbohydrates. Further studies are required to determine if such a diet helps prevent or treat IBD.
  • Dietary supplements: Because IBD affects areas of the intestine that are responsible for absorbing nutrients, some patients with IBD may have nutrient deficiencies. Others may have an increased need for certain antioxidants due to oxidative stress. Serum concentrations of several nutrients (beta–carotene, vitamin C, vitamin E, selenium, and zinc) were also significantly lower or deficient in IBD patients. These deficiencies indicate a need for intake of foods with high amounts of vitamins, minerals, and other essential nutrients, and possibly a multiple vitamin–mineral supplement.
  • B–vitamins: Supplements of B–vitamins may be effective in IBD patients. B–vitamins (vitamin B6, vitamin B12, and folic acid) decrease blood levels of homocysteine, which is thought to play a role in the development of IBD and has been shown to be in higher concentrations in the blood of individuals with IBD. However, clinical trials to assess benefits of homocysteine–lowering with B–vitamins in IBD have not yet been published.
  • Vitamin K: People with Crohn’s disease often have low levels of vitamin K in their bloodstreams. Although specific studies have not yet evaluated the benefit of vitamin K supplementation, a high intake of vitamin K–containing foods (e.g., green leafy vegetables) is advised.
  • Omega–3 fatty acids: Children with active disease have been shown to have lower levels of the alpha–linolenic acid, the primary omega–3 fatty acid. Long–chain omega–3 fatty acids (found in fatty fish, such as salmon) may decrease disease activity, and have been found in some studies to reduce medication requirements and help patients achieve remission more quickly than placebo. Whether plant sources of omega–3 fatty acids (e.g., flax oil) are equivalent to fish oils for this condition is not yet clear.
  • Botanical therapy:  Boswellic acids (the biologically active ingredient of Boswellia serrata) are an inhibitor of an enzyme that promotes inflammation. Bowellia acids were found to be effective in treating both Crohn’s disease and ulcerative colitis. In fact, one study showed that Boswellia achieved a remission rate greater than treatment with medical drugs. Clinical studies with larger numbers of patients are needed to assess these benefits.
  • Probiotic therapy: Lactobacilli, streptococci, bifidobacteria, Saccharomyces boulardii, and certain E. coli subspecies have been postulated to be useful by limiting the growth of harmful bacteria in the gut. A number of clinical trials have indicated reductions in disease activity and longer remission in patients with IBD who were treated with single or combined probiotics.

In addition to the nutritional interventions above, exercise can benefit IBD patients. Although only limited evidence suggests that exercise reduces risk for the onset of IBD, patients get many other benefits from regular activity. These include improvement of psychological symptoms; improvements in muscle strength and bone health, which are often impaired with steroid therapy; and a reduced risk for colon cancer.

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