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Can Omega-3s Help You Avoid Inflammatory Bowel Disease?
The science is young, but there’s a chance a high omega-3 diet could have real value against this challenging condition. 01/28/2021 by Temma Ehrenfeld

Inflammatory bowel disease (IBD) is the umbrella term for inflammatory conditions in the colon and small intestine. Crohn’s disease and ulcerative colitis are the two most common types.  

IBD arises when the immune system mistakenly attacks harmless food, viruses or bacteria in the gut, causing pain and injury. 

If IBD runs in the family, or you suffer from undiagnosed intestinal symptoms, there is evidence that a diet rich in omega-3s could help you avoid developing the illness. The science is moving along quickly. As one example, there’s now evidence for the long-controversial theory of “leaky gut.” 

IBD and “leaky gut”

Our intestines are lined with a layer of mucus, and with tiny holes or gaps between cell walls that allow nutrients to enter the bloodstream. For the most part, the food passing through the gut should stay in the gut until it is broken down into extremely small elemental nutrients that diffuse naturally through the intestinal walls, or remains as waste that is excreted.

Leaky Gut
Highly simplified rendering of tight and relatively open junctions between intestinal cell walls.

For years, however, researchers and some doctors have spoken about “increased intestinal permeability,” popularly known as “leaky gut.” The idea is that leaks in this layer allow only partially digested food, as well as toxins and bacteria, to enter the bloodstream and penetrate underlying tissues. Some of us might feel intestinal discomfort. In genetically vulnerable people, the leaks might trigger an immune reaction. The intestines become inflamed.  

To be clear, many doctors think “leaky gut” is nonsense. But last year, a large consortium of Canadian IBD researchers published research demonstrating that intestinal permeability may be a biomarker of future Crohn’s disease. They gave 1,420 healthy, first-degree relatives of Crohn’s disease patients a test: drinking a specific sugar solution and then seeing whether those sugars turned up in their urine. In people with a healthy gut, the urine wouldn’t be affected. It turned out that the people with more permeability were much more likely to go on to develop Crohn’s (Turpin et al., 2020). 

But why would the gut become too permeable? Here’s where omega-3s may come in. The cause may be the typical, highly processed Western diet.

The link between IBD and fatty acids

We know that fatty acids play a role in inflammatory cascades throughout the body, with the omega-6s promoting inflammation (especially when consumed to excess), and the omega-3s generally anti-inflammatory (Hsieh et al., 2020).

The typical modern Western diet gives us a ratio of 20 to 30 units of omega-6s to one unit of omega 3s. In traditional diets that relied more on fish and vegetables, the ratio was one to two units of omega 6s to one of omega-3s. That huge change is a big suspect in the rise of inflammatory diseases. As proof, epidemiologists cite the spread of IBD with the introduction of the Western diet to South America, Africa, and Asia in this century (Hsieh et al., 2020). 

One of the first epidemiological studies on nutrition and the increase in IBD in Asian countries came from Japan, showing that as the omega-3/omega-6 ratio increased, so did colitis (Schreiner, 2020).

Researchers have found evidence that links omega-6 consumption to IBD, for instance in an overview, analyzing nineteen studies that included more than 2,600 patients in all, about half with Crohn’s and half with colitis. Volunteers who ate more omega-6s had a higher risk of both illnesses in the future. Eating fiber and fruits was linked to a lower risk of developing Crohn’s and eating vegetables lowered the risk of developing colitis (Hou et al., 2011).

Research with a much bigger pool, more than 203,000 people, concluded that an estimated 30 percent of colitis cases could be attributed to a high intake of linoleic acid, the most common form of omega-6 (John et al, 2010).  Linoleic acid became a prominent source of calories in the American diet beginning in the 1970s when soybean oil became ubiquitous in processed foods (Whelan et al., 2013). 

In that group of people, the risk of developing colitis dropped 77 percent if for those who ate a great deal of docosahexanaenoic acid (DHA), an omega-3 that’s plentiful in fatty cold-water fish like salmon and black cod (Tjonneland et al., 2009).  

Another study analyzed consumption of omega-3s, following more than 25,600 people, ages 45-74, who completed seven-day food diaries and were monitored for between two and eight years. Eating more omega-3s appeared to help protect volunteers from colitis (John et al., 2010).

Should you take a fish oil supplement if you have IBD?

The best evidence that a supplement could affect the processes of IBD comes from animals (Barbalho et al., 2016). Human studies are small and the results are mixed. Taking a supplement has helped colitis patients take less medication when ill. It may help reduce pain (Barbalho et al., 2016). But studies suggest it won’t substitute for medication or prevent flares (Farrukh et al., 2014). 

Designing a diet for IBD

Researchers set out to design a diet specifically for Crohn’s and colitis patients, dubbed the Anti-Inflammatory Diet (IBD-AID), which encouraged consumption of foods with omega-3 fatty acids, especially fish and seafood. In a small test, 24 patients had either a good or very good response after reaching compliance and three had mixed results. All of them were able to discontinue at least one of their IBD medications, and all patients needed fewer trips to the bathroom (Olendzki, 2014).

How People With IBD Eat

Most IBD patients assume that diet influences their condition and could trigger relapses in symptoms.  But as much as half say they haven’t received any dietary advice from their doctors. Acting on their own, they tend to avoid certain foods rather than aim for a healthier diet overall.  They typically steer clear of spicy foods, vegetables, fruits, nuts, milk, red meat, soda, popcorn, dairy, high-fiber foods, coffee, and beans (Schreiner et al., 2020).

If the early research on the IBD-AID diet is confirmed by more studies, they would be better off eating an abundance of cooked vegetables, choosing from a long list of fruit, and perhaps most importantly, favoring fish and seafood for their protein.   


Barbalho SM, Goulart Rde A, Quesada K, Bechara MD, de Carvalho Ade C. Inflammatory bowel disease: can omega-3 fatty acids really help?. Ann Gastroenterol. Published Jan-March, 2016.

Farrukh A, Mayberry JF. Is there a role for fish oil in inflammatory bowel disease?. World J Clin Cases. Published July 16, 2014.

Hou JK, Abraham B, El-Serag H. Dietary intake and risk of developing inflammatory bowel disease: a systematic review of the literature. Am J Gastroenterol.  Published April, 2011.

Hsieh MS, Hsu WH, Wang JW, Wang YK, Hu HM, Chang WK, Chen CY, Wu DC, Kuo FC, Su WW. Nutritional and dietary strategy in the clinical care of inflammatory bowel disease.

Journal of the Formosan Medical Association. Published December, 2020.

John, S, Luben, R, Shrestha, S, Welch, A, Khaw, KT, Hart, A.  Dietary n-3 polyunsaturated fatty acids and the aetiology of ulcerative colitis: a UK prospective cohort study, European Journal of Gastroenterology & Hepatology. Published May, 2010.

Khalili, H., Chan, S.S.M., Lochhead, P., Ananthakrishnan, A., Hart, A., Chan, A. The role of diet in the aetiopathogenesis of inflammatory bowel disease. Nat Rev Gastroenterol Hepatol 15   Published May 22, 2018.

Limketkai BN, Wolf A, Parian AM. Nutritional Interventions in the Patient with Inflammatory Bowel Disease. Gastroenterol Clin North Am. Epub  Dec 7, 2017.

Olendzki, B.C., Silverstein, T.D., Persuitte, G.M. et al. An anti-inflammatory diet as treatment for inflammatory bowel disease: a case series report. Nutr J 13, 5 Published January, 2014.

Schreiner P, Martinho-Grueber M, Studerus D, et al. Nutrition in Inflammatory Bowel Disease. Digestion.  Published Jan. 10, 2020.

Tjonneland A, Overvad K, et al. Linoleic acid, a dietary n-6 polyunsaturated fatty acid, and the aetiology of ulcerative colitis: a nested case-control study within a European prospective cohort study. Gut.  Published Dec., 2009.

Turpin W, Lee S-H, Garay JAR, et al. Increased Intestinal Permeability Is Associated With Later Development of Crohn's Disease. Published August 10, 2020.

Whelan J, Fritsche K. Linoleic acid. Adv Nutr. Published May 1, 2013.


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