Diet and IBD

The Role of Diet in the Prevention and Management of Inflammatory Bowel Disease (IBD)

In 2017 following a diagnosis of Crohn’s disease, one of the first questions I asked my doctor was “what should I eat?” His answer was disappointing – “just eat a normal healthy diet.” Given that’s what I thought I was doing, this wasn’t super helpful.

Eight years on, as a newly certified health coach with a passion for nutrition and gut health, I have pulled together some of the latest research on diet and IBD so that you can confidently start acting now to prevent or manage this chronic condition.

What is IBD?

Inflammatory bowel disease (IBD) includes Crohn’s disease (CD) and Ulcerative Colitis (UC). They are both chronic, lifelong relapsing diseases of the gastrointestinal tract and are considered medically incurable. Although CD and UC present with similar symptoms, the location and histological features are different.[1] CD can affect any part of the digestive tract from the mouth to the anus whilst UC affects the large bowel (colon) only.

CD is considered more severe as both the lining and the wall of the digestive tract are affected vs only the lining of the colon in UC. When observed via colonoscopy, the lining of the digestive tract can appear swollen, ulcerated and inflamed in patients with active disease.

Disease onset is highest between ages 20 and 40, diagnosis often taking several years as symptoms can overlap with other conditions.[1] Disease symptoms are unpredictable, occurring intermittently followed by variable periods of remission.[1]

Although gastrointestinal symptoms are most often associated with IBD, other areas of the body can be affected. Symptoms can include abdominal pain, loss of appetite, nausea, vomiting, joint pain, arthritis, skin issues, eye inflammation, mouth ulcers, nutrient deficiencies, weight loss, temperature dysregulation, hormonal effects, extreme fatigue, brain fog, fever, constipation or diarrhoea and passing of blood or mucus from the rectum.

Experiencing these symptoms can have a huge impact on quality of life for the patient and their family with patients often describing their health as poor. Many patients may require hospitalization, surgery, multiple medications, and large amounts of time off school or work.

IBD Treatment

Standard medical treatment usually involves prescription of corticosteroids and other immune suppressants, including biologics (drugs made from a living organism) to dampen the immune response and achieve remission. However, despite the development of novel medications, just 10% of patients may achieve long-term and sustained remission.[2]

Approximately 16% of UC patients will have their colon removed within 10 years of diagnosis and between 70-90% of CD patients will require surgery during their lifetime.[3,4]

IBD Prevalence

Globally approximately 7 million people are currently living with IBD and this figure is rising.[5] Australia has one of the highest rates of IBD in the world with approximately 180,000 people affected, around 50% living with active disease, and the majority being working age adults.[6]

It is estimated that the economic impact of IBD in Australia is approximately $7.8 billion.[6]

What Causes IBD?

It was long regarded that IBD resulted solely from faulty genes, genetic studies identifying over 200 loci linked to IBD susceptibility.[7]

However, genetics alone cannot explain the exponential rise in IBD incidence over the last 50 years.[1] It is now believed that genes contribute to only 19-26% of the heredity variance of IBD and that environmental factors, including diet, play a key role in pathogenesis and inflammation.[7,8] Genes may load the gun, but environment pulls the trigger.

In 2016, a large genetic study by the IBD genetics consortium involving almost 30,000 IBD patients from 16 countries across Europe, North America and Australasia found that although genes predispose to disease, they do not define disease or severity.[9] They concluded that the genetic variants studied have a small effect and that environmental factors (including diet) are more important.[9]

It is now recognised that IBD is a multifactorial disease involving a complex interplay between genetic susceptibility, certain environment triggers including diet, immune response, and the microbiome.[10] See Figure 1.

Figure 1: The role of genetics, environment, immune response and gut microbiota in the development of IBD.[10]

In healthy individuals, commensal bacteria and the host intestinal immunity are in a balanced state, helping to maintain the integrity of the protective mucus layer, and resisting the invasion of pathogenic microorganisms.[11]

However, in individuals susceptible to IBD, changes in the composition of the gut microbiota due to environmental risk factors, including diet, cause an overactive immune response which damages the mucosal barrier and triggers inflammation.[11] See Figure 2.

Figure 2. Graphic showing how genetics, the gut microbiota, and an uncontrolled immune response cause defects in epithelial barrier function by affecting gut barrier integrity, increasing tissue destruction and mucosal inflammation.[11]

The Role of the Western Diet and Lifestyle in IBD

IBD was first recognised in the early 1800’s but it wasn’t until the 1950’s that an explosion of cases was seen in early industrialised countries. Until recent decades, it was virtually unheard of in less developed regions.[12] However, as these regions adopt a western diet, we now see a dramatic and continuous increase in cases.[13]

Key features of a western diet which may contribute to IBD promotion include:

• decreased intake of dietary fibre[14]
• increased intake of refined sugars[14]
• increased intake of ultra-processed foods[14]
• increased intake of meat and dairy products[14]

This dietary pattern can lead to gut dysbiosis; loss of microbiota diversity, loss of beneficial microbiota and overgrowth of harmful microbiota and this may be explained by multiple mechanisms.[15]

Mechanisms

1. Dietary Fibre

Adequate dietary fibre is essential for proper functioning of the gut and multiple studies suggest a protective role for dietary fibre in IBD development. Data collected from the Nurses’ Health Study following 170,776 women over 26 years showed that higher long-term intake of dietary fibre (25g/day), especially from fruit, was associated with a 40% reduced risk of developing CD.[16]

Fibre is an indigestible component of plant foods. Instead of being absorbed in the small intestine with other nutrients, it passes intact to our colon where it is broken down and fermented by our gut microbiota to produce short-chain fatty acids (SCFA’s), including butyrate. Butyrate directly fuels the cells lining our colon, promoting their growth and maintaining the integrity of the gut barrier.[17]

Butyrate also plays a role in gene expression regulation, apoptosis (programmed cell death), and the production of mucus which helps to reduce the translocation of harmful bacteria through the lining of the small bowel.[17,18]

Meat, fish, eggs, dairy and other animal-based foods contain zero fibre, and only minimal amounts may be found in ultra-processed foods. Most Australian’s fail to meet the recommended daily intake of 25g/day for women and 30g fibre/day for men.[19]

1. Food Additives in Ultra-Processed Foods

Epidemiologic data support an association between certain emulsifier exposures and incidence of IBD.[8] Although not sufficient to cause disease alone, they may synergise with other risk factors to promote disease.

Animal studies suggest that food additives commonly present in ultra processed foods may affect host barrier function or immunity.[8] Mice exposed to common emulsifiers carboxymethyl cellulose and polysorbate-80 developed increased intestinal permeability and thinning of the protective mucus layer, leading to increased proximity of the microbiota to the intestinal epithelium which may then allow microbes to penetrate the mucus layer resulting in intestinal inflammation.[8] Both CD and UC are characterized by high penetration of the mucus layer by bacteria and increased barrier permeability.[8]

Maltodextrin, used as a thickener and sweetener, has also been demonstrated in mice to affect mucosal proximity and impair clearance of Salmonella.[8] Carrageenan’s used for texture and thickening in dairy and sauces may induce intestinal permeability and enhance bacterial adhesion.[8]

1. Animal Protein and Fat

Research shows that increased dietary intake of animal protein and fat may contribute to increased risk of developing CD. A Japanese study examining the dietary patterns of healthy Japanese subjects from 1966-1985 found a strong correlation between the development of CD and increased consumption of total fat, animal protein and milk protein. Intake of plant protein was inversely associated with CD.[20]

The E3N study following 67,581 French women for 10 years found high (2g/kg/day) total protein intake was independently associated with a significant increased risk of IBD, particularly UC.[21] Vegetable protein was not associated with IBD.

A fascinating 2014 study fed healthy volunteers a healthy plant-based diet comprising grains, legumes, fruits and vegetables or a diet of meat, eggs and dairy for four days and analysed changes in their gut microbiota.[22]

Subjects eating the meat-heavy diet developed a pro-inflammatory microbiome within days with reduced abundance of Firmicutes (digest plant fibres) and increased numbers of bile tolerant species e.g., Bilophilia, Baceroidetes, an outgrowth of which may be capable of triggering IBD.[22] However, the opposite was observed when subjects swapped to the plant-based diet.

Several compounds found in animal products may contribute to the negative effects observed on the gut microbiota via multiple mechanisms. For example, haem iron found in red meat is pro-oxidative, pro-inflammatory, and increases risk of bowel cancer.[23]

Sodium nitrite and nitrate added to processed meat to preserve it, keep its colour and add flavour are a source of nitrite and N-Nitroso Compounds (NOC’s), known carcinogens. [23,24]

Inorganic sulphate and sulphites from red meat, cheese, milk, fish, nuts, eggs, plus those used as preservatives found in commercial breads, beers, alcoholic drinks, sausages, and dried fruits are converted by gut bacteria into toxic hydrogen sulphide which may contribute to increased disease activity in UC.[25]

Compounds produced by cooked animal products may also be detrimental to digestive health e.g. polycyclic aromatic hydrocarbons, heterocyclic amines, and advanced glycation end-products are pro-inflammatory, pro-oxidative and carcinogenic.[23,24]

Evidence to support a Plant-Based Diet

Several plant-based dietary approaches have been used to treat and prevent relapse in IBD, achieving remission rates significantly higher than with medications alone.

Exclusive enteral nutrition (EEN) has been used successfully for many years as a diet therapy to induce remission in paediatric CD patients and involves the exclusive use of liquid medical formulas for 6-8 weeks. The effect is believed to be dependent on the exclusion of ordinary table food.[7]

EEN is not a long-term solution and in 2014 a group of researchers from Israel developed the Crohn’s Disease Exclusion Diet (CDED) and tested it in 47 children and young adults with mild-moderate disease. Clinical remission (including mucosal healing) was achieved in 70% of patients.[26]

The diet involves 50% EEN (partial ENT or PEN) and 50% whole foods and is based on the exclusion of foods associated with unfavourable changes to the gut microbiome and protective mucus layer.[26] The diet is low in animal fat, rich in complex carbohydrates, and excludes all food additives.

In 2017 they tested PEN and the CDED in children and adults with CD who were failing biologics. A 90.4% clinical response was found at 6 weeks, with 61% achieving clinical remission. Of the 18 patients treated with whole food only, 77% achieved remission.[27]

Multiple Japanese studies by Chiba et al have also tested a plant-based diet in conjunction with medication in IBD patients, the aim being to increase beneficial bacteria in the gut. It can be described as a lacto-ovo vegetarian diet that allows for fish once/week and meat every other week (16% protein, 18.6% fat, 66% carbohydrate, 32.4g fibre/day).[28] The intention is that patients adhere to the diet for life for maximum benefit.

In 2010, 32 Japanese patients in a CD flare were prescribed infliximab and educated on a plant-based diet. They were followed for 2 years and 100% of those who had maintained the diet remained in clinical remission at 12 months. [29]

This approach was repeated in 2017 with 44 Japanese CD patients with 96% achieving clinical remission, 47% with full mucosal healing at 6 weeks.[30] Subsequent studies in 2018 and 2019 involving UC patients have achieved similar results.[31,32]

Specific Dietary Recommendations to Prevent and Manage IBD

IBD is a polygenic disease without a single solution. However, given the role of diet in shaping out gut microbiota, growing evidence strongly supports the role of a healthy plant-based diet in significantly modulating disease onset and activity.[1,33]

This can be described as a dietary pattern which restricts animal protein, animal fat, dairy, emulsifiers, added sugars and all food additives whilst providing increased dietary fibre i.e., a whole food plant-based (WFPB) diet.

Adoption of a WFPB diet may help prevent and improve quality of life for IBD patients by minimizing disease activity, severity, complications and the requirement for advanced medications (like biologics) and surgery.  A WFPB diet is also beneficial for overall health, IBD patients being at increased risk of comorbidities including cardiovascular disease and metabolic conditions.[34]

A WFPB diet aligns with multiple government dietary guidelines including the Australian Dietary Guidelines, the Canadian Dietary Guidelines, the UK Eat Well Guide and the EAT Lancet Planetary Health Diet.

My specific recommendations are to follow a WFPB diet containing:

• At least 30g fibre/day (ideally 40-50g/day) from whole plant foods including fruits, vegetables, legumes, whole grains, nuts and seeds. Aim to consume a total of 30 different plant foods/week to maximise gut microbiota diversity and resilience.
• Minimal intake of ultra-processed foods. Particularly avoid foods containing emulsifiers (lecithin’s, polysorbates, carrageenan, carboxymethylcellulose, sorbitan monostearate), maltodextrin (E1400), nanoparticles (titanium dioxide (E171), aluminium silicate (E599)), neotame – E961, sucralose and saccharine. Read food labels and choose foods without these ingredients where possible.
• Minimal intake of saturated fats from meat, eggs, dairy and tropical oils (coconut and palm oil). Favour mono or polyunsaturated fats from whole plant foods including avocados, olives, nuts and seeds.
• Minimal intake of added and naturally occurring trans-fat from cakes, biscuits, donuts, breads, ice-cream, dairy, beef, lamb and chicken.
• Minimal intake of dairy fats from dairy products. Choose plant-based alternatives fortified with calcium e.g., soy milk, soy yoghurt. If you wish to include dairy products, choose small amounts of low-fat fermented dairy e.g., kefir, plain yoghurt.
• Minimal intake of animal protein from red meat e.g. beef, pork, lamb. Choose plant-based sources of protein including tofu, tempeh, lentils, chickpeas, black beans etc.
• Zero intake of processed meat e.g., ham, sausages, salami etc. The WHO classifies processed meat as a class 1 carcinogen i.e., causes cancer. There is no requirement for processed meat in the Australian Dietary Guidelines.
• Aim to eat 3 main meals and 1-2 snacks where required within an 8-10 hour eating window to ensure you give your digestive tract and your gut microbiota a well-earned rest overnight. For example, have breakfast at 8am and finish eating by 6pm.

Note:

This information is not intended to replace the recommendations of your doctor. When making changes to your diet it is always best to seek professional guidance from a qualified nutritionist or dietician to ensure any changes are made safely and sustainably.

Patients experiencing active IBD may need specific guidance to incorporate dietary fibre in a way that does not aggravate a sensitive and inflamed digestive tract e.g., foods may need to be pureed or blended etc. Always seek professional support when required.

 

 

My Additional Lifestyle Recommendations

• Avoid smoking in all forms. Smoking is a known risk factor for CD development and can exacerbate symptoms.
• Minimize alcoholic beverages e.g., maximum of 1 drink/day for women and 2 drinks/day for men. Note: the safest level of alcohol consumption is zero.
• Minimize use of unnecessary medications where possible e.g., antibiotics, anti-inflammatories, oral contraceptives. Use of antibiotics in childhood, non- steroidal anti-inflammatories and oral contraceptives are risk factors for IBD.
• Undertake regular physical activity e.g., minimum 150 mins/week of moderate-vigorous activity e.g. running, swimming, tennis, netball, cycling etc.
• Get 7-9 hours restorative sleep per night.
• Practice stress management e.g., meditation, journalling, exercise, therapy. Don’t ignore the mind-gut connection!
• Spend quality time with friends and loved ones.
• Build a support network. Join support groups where the conversation around living with IBD is positive. Many IBD social media pages and groups are full of horror stories about the negative health effects of IBD which can amplify feelings of anxiety. Follow groups/people who are thriving and living well with IBD.
• Get regular blood work done to check inflammation and nutrient levels. Take a B12 supplement, especially if you eat 100% plant based. Vitamin D may also be required, especially in Winter.

If you need support implementing healthy diet and lifestyle habits to prevent or manage IBD, please seek help from a qualified nutritionist or dietician who works with IBD patients.

References

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