Crohn’s Disease, Ulcerative Colitis and Inflammatory Bowel Disease – An Evidenced-Based Second Opinion

Article written by Dr Renae Thomas –


There are an estimated two million people worldwide currently suffering from inflammatory bowel disease (IBD), comprising Crohn’s disease (CD), ulcerative colitis (UC), and pouchitis (1). These conditions are considered autoimmune in nature, whereby the body attacks normal healthy tissue, in these cases, the bowel, causing ulceration, pain, malabsorption, bloody diarrhoea, and damage to the intestines including perforations, strictures and obstructions, as well as an increased risk of bowel cancer. They are divided by the area they affect, with Crohn’s leading to destruction anywhere from mouth to anus, through the entire thickness of the intestinal wall, and ulcerative colitis being more localised to the colon, and surface layers only. Some people have a combined form known as ‘indeterminate colitis’, and others have disease manifestations outside of the bowel, such as arthritis, eye inflammation, skin problems and liver disorders.

Regardless of the definition, the cause and treatment is largely the same and will be discussed as such from here therein.

They are all generally considered ‘incurable’ by modern medicine, and follow a pathway of strong drugs to induce remission, repeated drug therapy and experimentation when the patient relapses, and surgeries when these fail, many of which offering little more than temporary symptom control.

As most cases are diagnosed before the age of thirty, this condition has a huge impact on one’s quality of life. Considering some of the newer drug therapies cost over $40,000 per year, and are associated with increased risk of other diseases (2), with no guarantee of remission, let alone cure, and high rates of relapse, perhaps it’s time to look if there are alternatives, or at least adjuvant treatments?


Before we start, let me preface with saying I am NOT anti-drug therapies. If one has an overwhelming infection, by all means do I say bring on the antibiotics. We live in a world where cutting yourself shaving no longer may mean a death sentence. However, what I do wish was more prevalent is true informed consent, with ALL possible options on the table. There is no denying that many drug and surgical treatments have helped many patients suffering with IBD, and I still recommend them at least temporarily in many cases, however, they only control the disease by suppressing the immune system to decrease the inflammation caused by the disease, or removing the affected area of bowel in the hope that no other area becomes affected, as opposed to addressing and removing the root cause of the disease.

This is largely because the cause is considered ‘unknown’.

This review highlights statistics of medical and surgical management:

Review article: remission rates achievable by current therapies for inflammatory bowel disease. (2011) (Peyrin-Biroulet L1, Lémann M) (3)

They found that at best, 20-55% of those on medications (ASA or steroids) went into remission. This leaves 45-80% still with active disease, which usually means stronger drugs are trialed. Of these, drugs such as azathioprine induced remission maintained for one year for only about 60%. Approximately 30-60% failed to achieve remission on methotrexate over a forty week period, with remission rates under 35% or less for infliximab, adalimumab or certolizumab. Those that cannot achieve and maintain remission under pharmaceutical therapy are often then referred to surgery. This review found that approximately one-fifth of CD and UC patients treated with biologicals require intestinal resection after 2-5 years.The authors concluded that in the era of biologics (new drug type), the proportion of patients with inflammatory bowel disease not entering remission remains high.

The risks of steroids, especially long term, is considered unsafe (4) due to severe side-effects,such as gastric ulcers, Cushing’s habitus (central obesity, moon face, red cheeks, wasted limbs), hyperglycemia, diabetes mellitus, muscle weakness, fragile skin, purple striae (stretch marks), flaring up of latent infections, delayed wound healing, cataracts, osteoporosis, glaucoma, and hypothalamic pituitary axis suppression (hormonal issues), with an increased risk of opportunistic infections and development of lymphomas (blood cancers).

There is evidence (5) to suggest that long-term use of steroid-sparing new drugs (biologics), especially infliximab, adalimumab, and certolizumab, may increase the risk of infections and malignancies, especially non-Hodgkin’s lymphoma.Combining these drug types with classical immunosuppressive drugs (such as steroids) is often contraindicated due to major adverse effects, including infection, malignancies and diverse immune reactions.


The current ‘best-practice’ medical care is the use of steroids, or steroid-sparing biological drug therapies to suppress the immune system to reduce the inflammation caused by the body attacking its own healthy tissue in the gut. When this doesn’t work, or ceases to work, portions of the bowel and/or anus are operated on or removed, often multiple times. The cause remains ‘unknown’, cures ‘are not possible’, and the treatment changes as new drug companies prove slightly (or seemingly prove) better results or less side-effects.


Despite the overwhelming amount of literature expressing improvement, remission or even cure of IBD with dietary changes, many patients are still unfortunately told things such as-

  • ‘Food has nothing to do with your disease’
  • ‘You’ll be on these drugs for the rest of your life’

‘Because the drugs are no longer working, you will need surgery to remove part of your bowel, and you will have to live with a bag through your abdomen collecting your excrement’.

Is there another option? Let’s start with prevention… because if dietary measures can predict incidence, illustrate increased risk, suggest prevention, and/or highlight mechanisms of pathogenesis, then this can support the idea that diet may have a role in disease management…


1. Epidemiological analysis of Crohn’s disease in Japan: increased dietary intake of n-6 polyunsaturated fatty acids and animal protein relates to the increased incidence of Crohn disease in Japan. (1996) Shoda R1, Matsueda K, Yamato S, Umeda N (6).

This study examined dietary changes in a relatively homogeneous (similar) population in Japan, from 1966 to 1985, to see how this correlated with the rising incidence of Crohn’s disease. Daily intake of dietary components, as well as incidence (new diagnosed cases) was assessed yearly for 19 years. They found a strong (P < 0.001) correlation of Crohn’s disease incidence with increased dietary intake of total fat, animal fat and omega six polyunsaturated acids, animal protein, milk protein, and increased omega six to omega three ratio, with increased animal protein being the strongest independent risk factor for developing Crohn’s disease.

2. Advances in nutritional therapy in inflammatory bowel diseases: Review. (2016) Andrzej Wędrychowicz, Andrzej Zając, and Przemysław Tomasik (7).

This review supported the prediction that an increased omega-six polyunsaturated fatty acid to omega-three polyunsaturated fatty acid ratio was associated with an increased risk of IBD. The foods high in omega-six polyunsaturated listed were beef, pork, corn/sunflower oils and margarine.

3. Dietary patterns and risk for Crohn’s disease in children. (2008) D’Souza S1, Levy E, Mack D, Israel D, Lambrette P, Ghadirian P, Deslandres C, Morgan K, Seidman EG, Amre DK (8).

This case-control study of children and adolescents found positive correlation between dietary patterns and the development of Crohn’s disease. The foods most associated with development of Crohn’s disease were higher intakes of meat, fatty foods, and desserts. Foods associated with decreased risk included vegetables, fruits, grains and nuts. The authors concluded- ‘There has been a rapid increase in IBDs as countries develop, and transition to a more ‘Western’ diet’.

4. Animal protein intake and risk of inflammatory bowel disease: The E3N prospective study. (2010) Jantchou P1, Morois S, Clavel-Chapelon F, Boutron-Ruault MC, Carbonnel F. (9)

The results of this ten year study concluded high total protein intake, specifically animal protein (including fish), was associated with a significantly increased risk of IBD. High animal protein intake was associated with a three-fold increase in inflammatory bowel disease risk.

5. A prospective study of long-term intake of dietary fiber and risk of Crohn’s disease and ulcerative colitis. (2013) Ananthakrishnan AN1, Khalili H, Konijeti GG, Higuchi LM, de Silva P, Korzenik JR, Fuchs CS, Willett WC, Richter JM, Chan AT. (10)

Long-term high intakes of dietary fiber, especially from fruits, was found to be associated with the lowest risk of Crohn’s disease in this study.

6. Lifestyle-related disease in Crohn’s disease: Relapse prevention by a semi-vegetarian diet. (2010) Mitsuro Chiba, Toru Abe, Hidehiko Tsuda, Takeshi Sugawara, Satoko Tsuda, Haruhiko Tozawa,Katsuhiko Fujiwara, Hideo Imai. (11)

This study discusses how epidemiology shows that IBD is more prevalent in wealthy nations where dietary westernisation inevitably occurs. Dietary westernisation is characterised by increased consumption of animal protein, animal fat, and sugar, with decreased consumption of grains. Increased intakes of animal fat and animal protein were especially related to the increased rates of Crohn’s disease. Other associated foods included sugar, fast foods, chocolate, bread, and cola drinks, as well as a decrease in fruit and vegetable fiber, and traditional Japanese foods (grains, vegetables, soy). The traditional Japanese diet, low in red meat, oils and fats and dairy products, was found to be a preventive factor against Crohn’s disease. Similar results in Canada are also included, outlining a positive association with a Western Diet, high in meat, fatty foods and desserts, and Crohn’s disease, whereas a protective effect was associated with diets higher in vegetables, fruits, grains and nuts. Diets rich in animal protein and animal fat cause a decrease in beneficial bacteria in the intestine, which is likely a contributing factor and/or risk factor for the development of Crohn’s disease.

7. Role of Diet in Inflammatory Bowel Disease. (2016) Ruemmele F.M. (12)

This article concluded there is an evident link between the change of food habits/food production and the incidence of IBD. Food additives/processing agents, such as maltodextrin, and emulsifying agents or thickeners, such as carboxymethyl cellulose, carrageenan and xanthan gum were shown to have detrimental effects on intestinal homeostasis. This is significant given that inflammatory bowel diseases are characterised by chronic inflammation and dysbiosis of the gut microbiota (13).

8. Diet and Inflammatory Bowel Disease: Review of Patient-Targeted Recommendations. (2013) Jason K. Hou, Dale Lee, James Lewis. (14)

This paper mentions how there are several pathways where diet may influence intestinal inflammation in inflammatory bowel disease, such as by direct dietary antigens, alterations of the gut microbiome, and effects on gastrointestinal permeability.

9. High-protein, reduced-carbohydrate weight-loss diets promote metabolite profiles likely to be detrimental to colonic health. (2011) Wendy R Russell, Silvia W Gratz, Sylvia H Duncan, Grietje Holtrop, Jennifer Ince, Lorraine Scobbie, Garry Duncan, Alexandra M Johnstone, Gerald E Lobley, R John Wallace, Garry G Duthie, and Harry J Flint. (15)

This study was able to demonstrate that in just four weeks, a high-protein, reduced carbohydrate diet could alter the microbiome and decrease beneficial gut bacteria, increasing risk for colonic diseases.

10. The urban diet and Crohn’s disease: is there a relationship? (2001) Mahmud N1, Weir DG. (16)

Another study discussing how patients with Crohn’s disease have higher dietary intakes of sucrose, refined carbohydrates and omega-six fatty acids (high in meat and dairy products), and a reduced intake of fruits and vegetables.

11. Diet and Crohn’s disease: characteristics of the pre-illness diet. (1979) Thornton JR, Emmett PM, Heaton KW. (17)

As above, another study finding that a diet high in refined sugar, low in fiber, and low in fruits and vegetables precedes and may favour the development of Crohn’s disease.

12. Diet, gut microbes , and genetics in immune function: can we leverage our current knowledge to achieve better outcomes in inflammatory bowel diseases? (2014) Vanessa A Leone, Candace M Cham, Eugene B Chang. (18)

This paper describes how a shift towards a Westernised high fat, high refined carbohydrate diet results in changes to gut microbiota structure and function that may trigger and perpetuate autoimmune diseases, by promoting pathological gut bacteria which alters immune function.

13. Diet and Inflammatory Bowel Disease. (2015) Karina Knight-Sepulveda, RD, Susan Kais, MD, Rebeca Santaolalla, PhD, and Maria T. Abreu, MD. (19)

This paper discusses how consuming a Western diet, high in fat (particularly saturated fat), can induce endotoxemia (even in healthy subjects), that may be sufficient to cause a leaky gut, with increased permeability and changes in the microbiota, resulting in systemic low-level inflammation. The increased omega-six to omega-three ratio is also discussed, with regard to its promotion of the pathogenesis of inflammatory bowel disease, and the increase in disease incidence over the past century correlating with a dietary over-reliance on vegetable oils (corn, safflower and cottonseed). The modern standard American diet (SAD) typically contains a ratio of 20-30:1 of omega-six to omega-three fatty acids, as opposed to the traditional ratio of 1-2:1. As omega-six fatty acids tend to be pro-inflammatory they are likely to contribute to the inflammation in Crohn’s disease. Omega-three fatty acids in contrast have strong anti-inflammatory effects and suppress pro-inflammatory players such as interleukins-1 and 6, and TNF-alpha.


So despite the common cry that ‘diet has nothing to do with inflammatory bowel disease’… there seems to be a few trends emerging. Based on the published evidence discussed above, for the best chance at preventing inflammatory bowel conditions, one should minimise or eliminate the following foods-

  • Animal protein (beef, pork, lamb, chicken, turkey, fish, seafood, milk, yoghurt, cheese, ice cream, eggs etc…)
  • Animal fat (as above)
  • Total fat (animal foods, fried foods, fast foods, processed foods, desserts, cakes, cookies, oils)
  • Milk protein (milk, cheese, yoghurt, ice cream, whey, buttermilk solids, skim milk solids, calcium caseinate, sodium caseinate, milk chocolate)
  • Omega six fatty acids- beef, pork, corn/sunflower oil, margarine
  • Food additives/processing agents (such as maltodextrin), and emulsifying agents or thickeners (such as carboxymethyl cellulose, carrageenan and xanthan gum) (processed foods, fast foods)
  • High sugar intakes (fast food, candy, soft drinks, cordial drinks, sweetened yoghurts, flavoured milk drinks, desserts)
  • Junk/refined/processed foods (cookies, candy, cake, fast foods, chocolate, soft drink)
  • Junk/refined/processed foods (cookies, candy, cake, fast foods, chocolate, soft drink)
  • Gluten, at least temporarily (wheat, rye, barley, triticale and products containing these, such as bread, cakes, cookies, cereals, pasta)

And focus on increasing the following foods-

  • Vegetables (all, cooked or raw, not fried or cooked in oil)
  • Fruit (all, cooked or raw, not stewed in sugar or made into jelly)
  • Grains (preferably whole grains- oats, brown rice, millet, cornmeal, buckwheat, barley, quinoa)
  • Traditional Japanese foods (rice, miso, yam, seaweed, fermented soybeans, edamame, radish, beancurd, potatoes, onion, corn, tomato, sesame, banana, tofu, eggplant, pumpkin, snow peas, citrus fruit)
  • Foods high antioxidants, vitamin C and vitamin E, not supplements (fruits, vegetables, turmeric)


Whilst they say prevention is better than cure, what if one already has the disease? Is there evidence to suggest diet can play a role, or perhaps even be better than current standard treatment? It is already known that elemental diets play a role, but why do patients relapse when food is introduced??? If an elemental diet can induce remission, which leads to relapse when food is reintroduced, how can it be denied that certain foods must be a cause, or at least a trigger?

Elemental diets are usually a prescriptive liquid formula containing nutrients such as amino acids, mono- or oligosaccharides, and medium-chain triglycerides, that require minimal to no digestion prior to absorption (37). These effectively work by allowing the bowel to rest, without fasting, and have been proven to be be as effective in producing remission of Crohn’s disease as corticosteroid treatment (38). The issue however, is this is not considered a long term dietary solution, and food is reintroduced. Most patients, soon after resumption of a normal diet have symptoms again, and almost all relapse during the first year (38, 39).

Remission, for modern medicine, is not elusive. There are relatively good results, using the elemental diets without meals, drugs such as steroids (such as prednisolone) or biologicals (such infliximab), and surgical resection, or a combination of these. The biggest problem for modern medicine in Crohn’s disease is maintaining this remission, and so life becomes a pattern of relapses, interspersed with bouts of remission, that require increasingly more complex methods to induce and maintain, with rarely over 25% in remission in a one year follow up (38).

So let’s take a step back… We have a condition that goes into remission when we remove food and most of the digestive process, that returns relatively promptly when food is reintroduced. Is it a stretch to suggest perhaps the types of foods that people are reintroducing, and perhaps the speed of which the digestive system is inundated with difficult to digest foods again, may have a role in disease relapse? Could there be certain types of foods responsible, that if avoided, could maintain remission?…

Let’s look at the literature again, this time for active cases, not just prevention…


1. Review article: evidence-based dietary advice for patients with inflammatory bowel disease. (2013) Richman E1, Rhodes JM. (20)

This 2013 review of the best available evidence of nutritional treatment and inflammatory bowel disease supported the recommendation of low intake of animal fat, meat, margarine, and processed fatty foods containing emulsifiers.

2. Environmental factors in a population-based inception cohort of inflammatory bowel disease patients in Europe–an ECCO-EpiCom study. (2014) Burisch J, et al. (21) This study found increased risk of relapse with high intakes of sugars, especially sucrose, and fast foods. These foods were also associated with worse disease severity and increased need for surgery.

3. Partial enteral nutrition with a Crohn’s disease exclusion diet is effective for induction of remission in children and young adults with Crohn’s disease.(2013) Sigall-Boneh R, Pfeffer-Gik T, Segal I, Zangen T, Boaz M, Levine A. (22) This study discusses how partial enteral nutrition, plus a very strict diet avoiding animal fat, high sugar intake, gliadin, and consumption of emulsifiers and maltodextrin, obtained excellent response and remission rates in both adults and children with Crohn’s disease (70-80%). The subjects also had normalisation of previously elevated C- reactive protein (a marker of inflammation) in 70% of the patients who achieved remission.

4. High Amount of Dietary Fiber Not Harmful But Favorable for Crohn Disease. (2015) Mitsuro Chiba, Tsuyotoshi Tsuji, Kunio Nakane, Masafumi Komatsu. (23) This study concluded that a plant-based diet not only is effective for gut inflammation but also promotes the general health of IBD patients… A high amount of dietary fiber is not harmful and seems to be favorable for Crohn’s disease.

5. Treatment of Crohn’s disease with an unrefined-carbohydrate, fibre-rich diet. (1979) K W Heaton, J R Thornton, and P M Emmett. (24) These researchers treated cases of Crohn’s disease with a fibre-rich, unrefined-carbohydrate diet in addition to conventional management, and followed them for a mean of four years and four months, comparing them to a control group not on the diet. For those with dietary intervention, hospital admissions were significantly fewer and shorter (111 days compared to 533 days in control group), and there was 1/5th the amount of surgeries in the diet group compared to controls. Despite many programs suggesting a low-fiber/low-residue diet, these results show that treatment with a fibre-rich, unrefined-carbohydrate diet appears to have a favourable effect on the course of Crohn’s disease and does not lead to intestinal obstruction.

6. Crohn’s disease: maintenance of remission by diet. (1985) Jones VA, Dickinson RJ, Workman E, Wilson AJ, Freeman AH, Hunter JO. (25)

Diets excluding specific foods patients are intolerant to, such as in this study can show remission rates of approximately 70% at 6 months to over four years, with annual relapse rates less than 10%.

7. Diet in the management of Crohn’s disease. (1984) Workman EM, Alun Jones V, Wilson AJ, Hunter JO. (26) This study describes how over 70% of Crohn’s disease patients remained in remission for over one year, using only a diet devoid of their specific triggers. The most important foods provoking symptoms were wheat and dairy products.

8. The value of an elimination diet in the management of patients with ulcerative colitis. (1995) Candy S1, Borok G, Wright JP, Boniface V, Goodman R. (27) This study again used elimination diets, excluding foods that appeared to provoke their symptoms. Compared to the control group, those in the dietary intervention group displayed significantly fewer symptoms, and had more improved sigmoidoscopic findings.

9. Lifestyle-related disease in Crohn’s disease: Relapse prevention by a semi-vegetarian diet. (2010) Mitsuro Chiba, Toru Abe, Hidehiko Tsuda, Takeshi Sugawara, Satoko Tsuda, Haruhiko Tozawa,Katsuhiko Fujiwara, Hideo Imai. (11)

This study used a semi-vegetarian diet based on traditional Japanese diets, high in brown rice, miso, yam, seaweed, fermented soybeans, edamame, radish, beancurd, potatoes, onion, corn, tomato, sesame, banana, tofu, eggplant, pumpkin, snow peas, and citrus fruit. Small amounts of animal foods were included to make the diet more acceptable, including egg wrapper, plain yoghurt, half a boiled egg, a half serve of fish once per week, and a half serve of meat once every two weeks. Dietary protein was 16%, fat was 18.6% and carbohydrate was 66%. In all 22 cases, there were no adverse effects such as gaseous distress, abdominal discomfort, or diarrhea as a result of the diet. Upon discharge, patients were encouraged to follow the diet and avoid known risk factor foods for IBD, including sweets, white bread, cheese, margarine, fast foods, carbonated beverages and juices. The semi-vegetarian diet was highly effective in preventing relapse in Crohn’s disease, with 100% remission at one year, and 92% at two years, compared with relapse rates of 60-70% at one year with standard medical care. C-reactive protein (a marker of inflammation) was normal at the final visit in more than half of the patients on the dietary treatment, indicating they will be free from relapse as long as they maintain the diet. The authors concluded that semi-vegetarian diets significantly decrease rates of relapse over a two year period (94% remission Vs 33% on an omnivorous diet).

10. Influence of dietary factors on the clinical course of ulcerative colitis: a prospective cohort study. (2004) Jowett SL1, Seal CJ, Pearce MS, Phillips E, Gregory W, Barton JR, Welfare MR. (28)

This study concluded that ulcerative colitis patients who consume more meat (especially red and processed meat), eggs, protein, and alcohol had a greater risk of relapse. Alcohol, burgers, red meat, and soft drinks were shown to be linked to increased disease activity.

11. Plant-Based Diets in Crohn’s Disease. (2014) Mitsuro Chiba, MD, Hideo Ohno, MD, Hajime Ishii, MD, and Masafumi Komatsu, MD. (29)

This paper provides further comment on the semi-vegetarian diet for treatment of Crohn’s disease and prevention of its relapse. Relapse rates in control group were 60-70% at one year, and 33% and 75% at one and two years on an omnivorous diet. On the semi-vegetarian diet, relapse rates fell to 0% and 8% at one and two years respectively, a significant difference and obtained in the absence of scheduled infliximab maintenance therapy or immunosuppressive agents, unlike the control group.

12. A Controlled Therapeutic Trial of Various Diets in Ulcerative Colitis. (1965) Ralph Wright and S. C. Truelove. (30)

This study identified triggers of milk, wheat, tomatoes, oranges, potatoes and eggs. They found that giving milk to patients in remission from ulcerative colitis can cause relapse and that they have much higher levels of antibodies to cow’s milk proteins. The results showed twice as many patients avoiding milk and milk products remained symptom free over one year.

13. Treatment of irritable bowel syndrome in outpatients with inflammatory bowel disease using a food and beverage intolerance, food and beverage avoidance diet. (2007)MacDermott RP. (40)

This study used a food and beverage intolerance avoidance diet. Foods associated with increased irritable bowel-type symptoms (gas, bloating, diarrhoea, constipation, pain) included milk and milk containing products, caffeine containing products, alcoholic beverages, some fruits, some fruit juices, spices, seasonings, diet beverages, diet foods, diet candies, diet gum, fast foods, condiments, fried foods, fatty foods, multigrain breads, sourdough breads, bagels, salads, salad dressings, some vegetables, beans, red meats, gravies, tomato pasta sauce, stews, nuts, popcorn, cookies, crackers, pretzels, cakes, and pies. Foods and beverages that were found more tolerable included water, rice, plain pasta or noodles, baked or broiled potatoes, white breads, plain fish, chicken, turkey, or ham, eggs, dry cereals, soy or rice based products, peas, applesauce, cantaloupe, watermelon, fruit cocktail, margarine, jams, jellies, and peanut butter.


As we can see… the treatment, and long-term management strategy/cure, looks very similar to the prevention plan, with additional thought given to spiced foods, condiments, wheat, caffeine, artificial sweeteners, all dairy, nuts, citrus fruits, nightshades, and alcohol.

So let’s put it all together… In inflammatory bowel diseases we have inflammation and oxidative stress in the gut, an overactive immune response, an altered gut microbiome, and an increased risk of colon cancer. We know that what we eat spends a significant amount of time in the gut. We know a plant-based diet is high in antioxidants, reduces inflammation, feeds a healthy microbiome, supports healthy immune function, decreases our risk of cancer, is high in many of the preventive and treatment foods, and avoids many of the common triggers. Could it be worth a try??


There are numerous factors supported by research as to why plant-based foods are useful in healing inflammatory bowel conditions

1. Gut microbiome profile

A healthy microbiome is absolutely essential to a healthy gut (41), and whilst new research in this area is emerging almost daily at the moment, we know the bacteria in our guts vary between people and populations, suggesting influence of genetics, diet and environment. Both long term and short term dietary intake influences the structure and activity of the microorganisms as well as their type (42). A study (42) comparing two diets, a plant-based one (granola, rice, fruits, vegetables, vegetable and lentil curry) and an animal-based one (bacon, eggs, coffee, cream, pork, beef, cheese, processed meats) found that in less than five days, dietary intake alters microbial community structure and microbial gene expression. The animal-based diet lead to increased levels of bile-tolerant microorganisms (Alistipes, Bilophila and Bacteroides) and decreased levels of Firmicutes that metabolise dietary plant polysaccharides (sugars) (Roseburia, Eubacterium rectale and Ruminococcus bromii). The increased abundance and activity of Bilophila wadsworthia on the animal-based diet illustrates a link between dietary fat, bile acids and the outgrowth of microorganisms capable of triggering inflammatory bowel disease (42).

Another study (23) concluded that based on knowledge of gut microflora, the greatest environmental factor in IBD is diet-associated gut microflora. Consumption of a Westernised diet, high in animal fat, animal protein, and sugar, and low in dietary fiber causes disruption of the microflora in IBD (23).

2. High Fiber intake

Fiber is found only in plant foods, thereby every portion of animal foods included in the diet decreases the amount of fiber contained in the diet. Increased dietary fiber has favourable effects on the microbiome and is related to both increased remission and decreased risk of development of IBD (23). Even just meeting the recommended dietary intake of fiber (which is more than most of the Western population consume) showed benefit for Crohn’s disease, most likely by altering microbiome bacteria (23). Switching to a plant-based diet can easily raise fiber intake rose to over 25g/1,000kcal (42), more than double typical minimum requirements, and far more than typical intakes. Mechanisms for which fiber is useful in IBD include improved laxation, increased stool bulk, decreased stool transit time through the bowel, increased excretion of bile acids, estrogens, fecal procarcinogens and carcinogens, anti-inflammatory properties, and improved general health and wellbeing (lower cholesterol, improved insulin sensitivity, lower blood pressure, healthier body weight) (23).

3. Anti-inflammatory

Soluble fiber, found only in plant-based foods, is the best way to generate short-chain fatty acids, such as butyrate in the gut, which have anti-inflammatory effects (43, 44). Vegetarians with long-term consumption of fruits and vegetables have lower levels of C-reactive protein (marker of inflammation) (45). Vegetarian diets are high in important sources of dietary salicylates as well as other anti-inflammatory compounds (45). Plant foods high in polyphenols and antioxidants have been found to be extremely beneficial in the prevention and mitigation of IBD due to their intrinsic ability to scavenge free radicals, induce anti-inflammatory responses, maintain a homeostatic regulation of the gut microbiota, and activate the intestinal T regulatory cells(46). Flavonoids are high in plant-based foods, especially fruits and vegetables, and have been demonstrated to exhibit a broad spectrum of biological activities for human health including anti-inflammatory properties (47).

4. Less sulphur compounds

Animal products are the main sources of sulfur containing amino acids, which leads to the production of hydrogen sulfide by intestinal bacteria when these foods are consumed. Hydrogen sulfide has been found to be toxic to the cells of the colon, and hence is suggested to play an important role in IBD causation and treatment (48).

5. More antioxidants and phytochemicals

Polyphenols (high in vegetables and fruits) are considered the most abundant antioxidants in the human diet. Phytochemicals (such as polyphenols, flavonoids) have been shown to modulate inflammatory immune cells such as TNF-alpha, IL-1, and IL-6 in a way that could be favourable for IBD (49).

6. Avoidance of fillers, processed foods and artificial foods

Focusing on consuming whole plant foods minimises exposure to microparticles (such as titanium dioxide and aluminosilicates/anti-caking agents) known to be triggers for IBD. These are found in processed foods (for example baked goods, desserts, and cake mixes). A microparticle- free diet has been shown to be helpful in IBD, decreasing inflammation and disease activity (51, 52). Titanium dioxide, used as a food colourant, is another microparticle suggested to contribute to intestinal inflammation (53, 54), and hence likely to be best avoided in IBD. Mixed silicates and titanium dioxide can accumulate in the immune cells of the gut and some evidence suggests this exacerbates inflammation in Crohn’s disease (55).

7. Overall health benefits

Treatment with a vegetarian diet also reduces the risk of common diseases that people with IBD face in common with all of society, including coronary artery disease, heart disease, cancers, and type II diabetes mellitus (50).


As all medicine is supposed to be, medical treatment protocols should be based on the outcomes of the most credible and accurate research. Whilst there are no absolutes in medicine, the best available evidence discussed so far definitely suggests altering food intake could be manipulated to a beneficial degree. So where to now if you (or a loved one) is suffering from inflammatory bowel disease??

I always recommend starting at the least restrictive option with dietary changes, and increasing the level of food elimination as needed. This allows for as much flexibility as possible, maximises micronutrient intake, increases compliance, and minimises the temptation to stray from the diet. The nutritional guidelines I recommend for optimal health, based on the best available evidence, doesn’t change much, it’s a whole food plant based diet and it works wonders for almost all health conditions. However there are some tweaks that can make recovery from inflammatory bowel conditions more successful and long lasting.


The first step would be to remove common allergens and triggers identified in the scientific literature, and as discussed above. These would be-

  • Meat, fish, seafood, poultry, eggs
  • All dairy products
  • Oils (yes, even extra virgin olive oil and coconut oil, or whatever oil is flavour of the month!), margarine, butter and ghee
  • Fast foods, processed foods, cookies, cakes, candies, chocolate, soda etc…
  • Gluten containing grains (wheat, rye, barley, triticale)
  • Alcohol
  • Spicy foods
  • Artificial sweeteners, diet foods and drinks
  • Potentially citrus fruit, corn, tomatoes, nightshades and strawberries (usually only temporarily whilst the inflammation gets under control)

Foods to enjoy include-

  • Fruits
  • Vegetables and salads
  • Starchy vegetables such as sweet potatoes, winter squashes, pumpkin, carrots, beetroot
  • Legumes such as kidney beans, lentils, chickpeas, black beans etc…
  • Gluten-free whole grains such as gluten-free oats, brown/red/black rice, millet, quinoa, cornmeal, tapioca etc…

Sample menu-

1. Bowel rest phase-

  • You may start with water to get symptoms under control (no more than 2 days without medical supervision), or use green juices instead (no more than 3 days unsupervised).

2. Nutrient-rich healing phase-

  • Fruit and green juices (another 1-2 days). Use simple combinations, such as watermelon/celery, apple/celery/cucumber, pear/cucumber/spinach. No citrus fruits.
  • Salt and sugar free vegetable broths (homemade by boiling water with vegetables).

3. Gentle, soothing phase-

Incorporate foods such as-

  • Some fruits- very ripe papaya, watermelon, cooked peaches/apricots/plums
  • Well cooked and pureed zucchini/summer squash, pumpkin/winter squash, or sweet potato.
  • Pureed vegetable soups

4. Rebuilding and healing phase-

Slowly add in more complex foods, always assessing for triggers-

  • Smoothies with ripe bananas, spinach and celery
  • Apple sauce
  • Well cooked (and initially pureed) vegetables
  • Rice congee
  • Pureed beans

5. Maintenance phase-

Slowly add in foods in the following order-

  • Well cooked vegetables and starchy vegetables
  • Soft, ripe fruits and cooked fruits
  • Rice, then other gluten free whole grains
  • Salad and raw fruits
  • Legumes
  • Nuts/seeds (start with nut and seed butters and ground flax before whole), and avocado
  • Nightshade vegetables
  • Citrus fruits
  • Unprocessed/minimally processed soy foods, if desired (edamame, tofu, tempeh, nutto)
  • Gluten containing whole grains, if desired


  • Minimise use of pain-killers, such as acetaminophen/paracetamol, and ibuprofen. There are studies illustrating they are associated with increased IBD disease activity (31, 32). Non-steroidal anti-inflammatory drugs (such as ibuprofen), can exhibit harmful effects in IBD by altering the natural process of inflammation and healing (33).
  • Minimise/eliminate oral contraceptive use, especially if you are/have been a smoker (of which you definitely should seek help to quit) as they have been associated with risk of Crohn’s disease and ulcerative colitis (34).
  • When re-introducing foods, consider starting with low FODMAP foods (I recommend a plant-based version only). A recent study showed approximately 50% improvement rate in functional gut symptoms (bloating, abdominal pain, wind, diarrhoea) in IBD patients using FODMAPs (35). A FODMAP chart can be found here-
  • Optimise the rest of your health. The last thing someone with IBD needs is another acute or chronic illness or disease! Along with diet be sure to be physically active (walk or exercise for at least 30-90 minutes per day), get plenty of restful sleep, quit smoking/alcohol/caffeine/drugs, get daily sunshine (if possible), manage stress via yoga/meditation/mindful practices, maintain a positive attitude, and be social, whether with friends, family, volunteering or work-related.
  • Rebuild the body. One in remission and eating a wide variety of foods, focus on incorporating high energy, easily digestible foods, with high nutritional value, as malnutrition can be common when one is suffering IBD (56). This could include foods such as nut and seed butters, applesauce, homemade hummus and bean dips, sweet potatoes, oatmeal, fruit smoothies, and bananas. Lean body mass, and bone mineral density in people with IBD is often lower than the healthy population, so adding some resistance training and weight bearing exercise will be beneficial to health (56).


Is there a role for supplementation?

Because people are so used the the pill /drug treatments of illness, it is very common that those seeking ‘alternative medicine’ look to supplements that may help them. The key to remember with these is conveniently in their name… they can only supplement a healthy diet and lifestyle, not correct it or override it! I recommend cautious use of supplements, as evidence is emerging many cause more harm than good, especially long term (see 36 for referenced articles on this topic). However, there is research supporting that there are a few that may be considered in IBD, as follows-

1. Dr Klaper’s Leaky-gut protocol (57)

‘Leaky gut’ or increased intestinal permeability is exaggerated in those with inflamed intestines, such as in IBD. Gut permeability believed to play an important role in Crohn’s disease, with abnormalities in tight junctions between cells in the gut allowing increased antigen uptake, which may increase inflammation (58). The gut ‘leakage’ can be decreased by stopping damage to the intestinal wall or intestinal flora, by following the diet and lifestyle advice as described above, and this can be enhanced by incorporating the following supplement regime for 90 days (a few cycles of new gut lining) (57)

  • 650-1000 mg L-glutamine, twice daily, half to one hour before meals (feeds intestinal cells to support healing)
  • 650-1000 mg Quercetin, twice daily, half to one hour before meals (tightens gaps between cells)
  • 2 capsules of a non-dairy probiotic, 1 hour before meals or 1 hour before bed.

Probiotics vary greatly, and for this purpose the ideal is one that is non-dairy, and contains some of the following strains- Lactobacillus acidophilus, Lactobacillus. plantarum, Lactobacillus. salivarius, Lactobacillus. bulgaricus, Lactobacillus. casei, Lactobacillus. bifidus, Lactobacillus. rhamnosus, Bifidobacteria. longum. Whilst I do not endorse any particular brand, three studies on the probiotic mix sold as VSL#3 have been evaluated, finding 44% rate of remission in ulcerative colitis patients treated with VSL#3 compared to 25% with placebo (59).

2. Omega-three fatty acids

Whilst the research is somewhat hard to reach a conclusion from, especially when the studies tend to use a fish oil, there is some evidence (60), that increasing omega three fatty acids can have an anti-inflammatory effect (as does decreasing omega six fatty acids). This can come from dark leafy green vegetables, walnuts, chia seeds, ground flax seeds, or hemp seeds. DHA/EPA supplements from algae, evening primrose oil, and/or GLA (gamma-linolenic acid) capsules are also sometimes used, especially during healing when oral intake may be poor (57).

3. Turmeric

Curcumin, the active compound in turmeric, has been shown in a few studies to help maintain remission in IBD (60). This is likely due to its anti-inflammatory and antioxidant properties, but more research is probably needed to confirm this (61). As adding a dash of turmeric to meals is likely harmless, it could be worth a try!

4. Vitamin D

Addition of vitamin D, or increasing levels of vitamin D at least into the normal range (30-45 ng) for those with malnutrition and/or low levels has been shown to increase the efficacy of IBD therapy. This can be via safe sun exposure or through a supplement (62), though I do caution use of vitamin D supplements, until their safety is conclusive (63), and recommend supplements only when clinically low and not responsive to, or unable to utilise safe sun exposure.

5. Reversing deficiencies that can occur in IBD (if present)

If a deficiency is clinically identified, short term supplementation with vitamins and minerals, such as zinc, selenium, iron, iodine, folate, and/or B vitamins, may be of benefit (7). I suggest judicious use, with medical monitoring, if using supplements. Foods high in these nutrients, that could be worth increasing in the diet include dark leafy greens, prunes, raisins, beans, lentils, red pepper, strawberries, berries, sea vegetables, and whole grains.

6. Wheat grass

A small, but clinically controlled trial assessing the efficacy of daily wheatgrass in a treatment protocol for active ulcerative colitis found significant reductions in overall disease activity index and severity of rectal bleeding, based on patient records, a sigmoidoscopic evaluation, and global assessment by a physician (64).

7. Other

Other, weaker evidence suggests potential benefits from aloe vera juice, licorice tea, slippery elm, ginger, buckwheat, parsley, and apricot (46).


Whilst case-studies or stories of individuals cannot be regarded as highly as clinical trials and published, peer-reviewed literature, it can be helpful for some people to know they aren’t alone, and that real people (as opposed to statistical patients) are using this advice and curing their disease! As such I have included some here-

1. A case study of a man who brought on ulcerative colitis by following a low-carbohydrate, high-meat, high-fat, Atkins style weight loss diet, and his subsequent hospital remission following a plant-based/semivegetarian way of eating-

2. Suzie’s three year remission from Crohn’s disease following a plant-based protocol from Dr Carney –

3. Somer’s journey of how she went from using the bathroom up to 30 times a day, in extreme pain, and suffering drug side effects, to using the Forks over Knives plan to heal and come off all prescription drugs and enter full remission from ulcerative colitis-

4. Ryan’s story of how he went from a weightlifting, high-protein diet following veterinarian and athlete, to suffering with Crohn’s disease so badly that could barely eat, was in severe pain, fatigued and depressed, with little improvement from the best medical care. On finding the McDougall Elimination Diet, he is off all his medications, and feels better than before he was even diagnosed!-

5. Shamiz’s well documented pathway to wellness from ulcerative colitis with copies of his medical reports showing his colon healing from the inside!-

6. Peter’s description of how eating whole-food, plant-based, with especially no dairy, and lots of high fiber, low-fat plant-based foods has kept him free of Crohn’s symptoms for over thirty years-

7. Another McDougall success story Andrew details how, after being told 99% of people with ulcerative colitis as bad as his would have died by age 35, got off all of his strong medications (and rid of their negative side-effects) and has been free from any symptoms since 2010-

8. Gabrielle went from being in constant pain, with bleeding bowel movements, and fatigue to coming off all medications through the McDougall Program and True North Health Centre, and now has no pain or blood in her stools, and has regained her life-


I do hope that this information will help you, or your loved ones heal from, or at least improve their life with IBD. Worst case scenario, even if this diet change has absolutely NO impact on the IBD, at least a wholefood plant-based diet can prevent and reverse our number one killer, heart disease… as the last thing someone with IBD needs is another illness as well! Plant-based diets are known to provide therapeutic and/or preventive effects against almost all current major chronic diseases (23). So you are giving yourself the best chance of living in optimal health, in all other areas of life, even if you still struggle with some symptoms of IBD. My prediction however, is that you wish you knew this sooner…

Let food be thy medicine and medicine be thy food.

Be well 🙂

Dr Renae Thomas


































































Shukul Kachwalla

Shukul Kachwalla is a Certified Wholistic Health & Natural Healing Counsellor from the Vibrant Health & Wealth Academy. Shukul has recovered from severe Hayfever, Acne, and Chronic Migraines and recommends a Whole Foods Plant based diet to people who want to improve their quality of life and experience optimal health.