tomato salad in white bowl with bread and oil

If you have ulcerative colitis, knowing what to eat can be tricky. It’s important to customize your food choices based on your current tolerance and health goals. This post will help you understand the current scientific thinking on ulcerative colitis and diet and how to move forward with the approach that is right for you.

As a registered dietitian working with clients with Crohn’s disease and ulcerative colitis for over ten years, it’s an area I am passionate about because of the massive toll these diseases take on people’s quality of life. I also believe that nutrition and foods rich in fibre can play a much larger role in the management of the diseases than is often discussed in the doctor’s office.

As a dietitian, I believe that the goal of nutrition is more than just ensuring you get all the vitamin D you need. I believe – and have seen firsthand in my practice – that creating a strong individualized approach to nutrition can help people find healing and learn how to thrive, no matter their diagnosis. Which is why it is frustrating that much of the scientific literature on ulcerative colitis is focused on either associating the risk of disease with certain foods, or acute strategies for securing remission in a flare. 

In this post, I am going to share my strategies to help people with ulcerative colitis manage their bowel movements, inflammation and improve their long term gut health. But before we get started, remember that this is general advice. Because I am not able to know your unique medical history, it’s important for you to discuss the information you read here with your dietitian or doctor to decide if it is right for you.

What is ulcerative colitis?

Ulcerative colitis is an inflammatory bowel disease that affects that affects the colon, or large intestine. Typically, the inflammation starts in the rectum and then extends continuously throughout the colon. It is commonly diagnosed in your thirties, and takes a flare and remission pattern where sometimes you feel okay and other times you don’t.

Ulcerative colitis vs Crohn’s disease

Crohn’s Disease is another inflammatory bowel disease that shares similarities to ulcerative colitis, with a few key differences. The first is that Crohn’s disease can technically occur along the entire length of the GI tract, as opposed to ulcerative colitis occurring exclusively in the colon. Crohn’s disease also presents in discontinuous ‘patches’ as opposed to the continuous diseased areas in ulcerative colitis. Imbalances in gut bacteria (known as dysbiosis) tend to be more pronounced in Crohn’s disease than ulcerative colitis. Finally, the inflammation in ulcerative colitis typically does not go as deeply into the gut tissue layers as in Crohn’s disease, but both diseases show evidence of gut barrier dysfunction, or ‘leaky gut’. I have advice on nutrition for Crohn’s disease too.

Ulcerative Colitis Diet: Foods to Eat and Foods to Avoid

Here in Canada, we have one of the highest rates of ulcerative colitis in the world; it is thought that our environment + lifestyle weigh heavily on our risk for the disease.

Most people with ulcerative colitis report that food impacts their symptoms, so it’s important that nutrition is not overlooked in the management of the disease. Recent evidence suggests that intake of certain foods is associated with a higher risk of ulcerative colitis, including:

  • Meat, particularly red meat
  • Sugar, and sugar sweetened beverages
  • Omega 6 fatty acids (arachidonic acid)

We also know that the inflammation and increased bowel movements in ulcerative colitis and Crohn’s disease can lead to malabsorption, low food intake and nutrient deficiencies along with osteoporosis. So everyone with ulcerative colitis should be receiving adequate nutrition therapy.

Foods to eat with ulcerative colitis

My long-term nutrition goal for my clients with ulcerative colitis is always to move towards an anti-inflammatory diet where they eat as many whole plant foods as possible. It is thought that a more Mediterranean or anti-inflammatory diet pattern contributes to an healthier community of gut bacteria, a stronger gut barrier and a better immune balance between tolerance and inflammation. In one clinical trial, a plant-based diet improved relapse rates in ulcerative colitis.

Other lab research suggests that a Mediterranean-style diet decreases risk of colitis. However, because of the nature of inflammation and irritation, it can often take very slow and sustained change over time to increase intake of plant-based foods comfortably. 

  • Fruits and Vegetables

Fruits and vegetables have been associated with a decreased risk of ulcerative colitis. They are high in anti-inflammatory phytochemicals and fibre, which is critical for production of short chain fatty acids by our gut bacteria that help to ease inflammation and support gut barrier function.

However, this advice has to be tempered with the current state of your tolerance. If eating a salad causes pain and diarrhea for you, you should not be eating a salad every day! Instead, in my practice we focus on adding tolerated forms of vegetable to each meal, such as eating small amounts of soft vegetables like peeled cucumber, or cooked vegetables like sweet potato, or adding spinach to a smoothie. We do this consistently, increasing portions as tolerated before moving on to harder to digest foods.

  • Omega 3 rich seeds

We all need omega 3 rich foods in our daily diet; ulcerative colitis is no exception. Data suggests that increased intake of omega 3 rich foods decreases risk of ulcerative colitis but clinical trials on fish oils have not offered conclusive benefits to disease outcomes. 

The easiest way to get omega 3s in the food world are the omega 3-rich seeds – ground flax, ground chia and hemp hearts. These foods are also usually well tolerated because of their soluble fibre content. Always eat chia and flax ground as intact may be too hard on your gut. We work up to two to three tablespoons a day slowly and sometimes, I add a supplemental form as well.

  • Calcium- and magnesium-rich foods

People with ulcerative colitis are at higher risk of bone loss due chronic inflammation and corticosteroid use. Magnesium deficiency is also common in ulcerative colitis. If you are choosing to avoid dairy because you feel it flares your symptoms, you can absolutely get all of the calcium and magnesium you need from plant-based foods like tofu, hemp hearts, beans and tahini.

  • High Fibre Foods, as tolerated

Fibre is critical for improving the gut microbiota (gut bacteria) and is a key factor in lowering chronic inflammation. Higher fibre diets are also associated with lower risk of inflammatory bowel disease. However, high fiber foods like beans, intact whole grains, nuts and seeds are not always tolerated by an inflamed and irritated gut. 

Soluble fibre, which is gel-forming in the gut – such as oranges, oats, barley and psyllium – tends to be better tolerated than insoluble fibre from grains and fibrous vegetables. In practice, I will often build fibre intake very slowly, starting with soluble fibres and then cooked and blended sources of insoluble fibres. 

  • Turmeric

Turmeric is my fave anti-inflammatory spice and its active component curcumin is well-studied in ulcerative colitis. The recommended dose is 1 gram of curcumin, twice a day – which is pretty high. If that dosage is not available or affordable to you, I recommend working 1 teaspoon of turmeric into your diet each day in smoothies, mild curries or warm turmeric milk.

  • Psyllium

While it does not work for everyone, psyllium can feel like a bit of magic when it works. Psyllium is a unusual soluble fibre that regulates digestion without being highly fermentable AKA causing a lot of gas and bloating and irritation. We start with 1 teaspoon of psyllium a day with lots of water. If it is tolerated, we work up to a tablespoon daily over the course of a few weeks. Within about a month, you should know whether psyllium is helping you minimize your bowel movements alongside a healthy diet.

Foods to avoid with ulcerative colitis

  • Added sugars and hyper-processed foods

Our North American love affair with low fibre, high sugar and high fat hyper-processed food is associated with our risk of ulcerative colitis. It is this type of eating that is thought to drive gut dysbiosis – or the overgrowth of more pro-inflammatory gut bacteria that can harm gut barrier integrity leading to leaky gut and inflammation. In laboratory studies, this type of diet can decrease the number or acetate and butyrate producing bacteria and increase the risk of colitis.

Another issue with hyper-processed foods is that they contain emulsifiers like xanthan gum and carrageenan which may alter gut barrier integrity. While their true impact on gut health is still hotly debated, in one double-blinded trial, people with ulcerative colitis on a carrageenan free diet had lower relapse rates than those given two capsules of carrageenan. For me, this would not be the first place I look when adjusting someone’s diet – instead, it would be a refinement only after taking more global steps towards a more whole foods, plant-based approach.

  • Meat, particularly red meat

Red meat is associated with risk of inflammatory bowel disease. While intervention trials have not confirmed that removing red meat from the diet will improve ulcerative colitis outcomes, I do feel that the balance of research on how red meat may alter gut health is intriguing enough that this is a recommendation in my practice. For example, red meat is a source of omega 6 linoleic acid, which is metabolized to arachidonic acid, which is associated with disease risk. High iron intake – rich in red meat – may also increase inflammation in the colon. In addition, the availability of sulfur in the colon – which may be increased by a meat-heavy diet – is associated with ulcerative colitis outcomes.

If you aren’t a huge fan of red meat, ditch it entirely. If you truly love red meat, try to limit yourself to one 3-4 ounce portion every week or two, no more. 

  • Dairy

Contrary to popular belief, research has not confirmed that dairy is associated with ulcerative colitis severity or risk of developing ulcerative colitis.  In fact, data suggests that eating dairy bears a decreased risk of Crohn’s disease, but the same is not true of ulcerative colitis. There have been clinical trials testing dairy removal in UC; improvements were seen but they did not reach statistical significance.

In practice, some clients feel that they improve when they remove it from their diet which given the individualized nature of nutrition in ulcerative colitis, is reason enough to make the change. Dairy is not an essential food so if you don’t want to eat it, don’t.

Dairy could be impacting symptoms for a few reasons:

  • People are lactose intolerant and gut irritation makes these symptoms worse
  • The dairy they are eating is in the form of higher fat, higher sugar, more processed foods like ice cream or sweet coffee drinks that drive inflammation and gut issues
  • There is a connection between gut barrier dysfunction, dysbiosis and saturated fat intake; some forms of dairy like cheese and full fat yogurt or milk are higher in saturated fat.
  • Omega 6-rich cooking oils like soy, corn and safflower oils

Omega 6 fatty acids are associated with disease risk and research suggests that minimizing them in the diet is a good idea. Meat is a much bigger source of omega 6 than you might expect but the other big source are vegetable cooking oils. I recommend replacing all cooking oils with either extra virgin olive oil or avocado oil which are primarily monounsaturated fatty acids that do not drive inflammatory processes.

Is there a specific ulcerative colitis diet? 

There is not one gold standard ulcerative diet. Instead, there is evidence-informed and individualized approaches to help you feel your best. At this point, there have been a few studies looking at particular dietary styles but we don’t have a lot of evidence to go on here. 

Plant-based diet for Ulcerative Colitis

Given the association with a more Western, pro-inflammatory diet style with negative outcomes in ulcerative colitis, I highly recommend that an anti-inflammatory diet become the end goal for anyone with the disease. In my mind, this is a mostly whole foods, plant-based diet. As I mentioned earlier, one trial found that a plant-based diet improved outcomes; another trial looked at a ‘semi-vegetarian’ diet which was also shown to be successful versus an standard meat-based diet.

Plant-based diets, in addition to their decrease in meat and increase in fibre and phyto-chemicals, are also rich in potassium – which may be important for offsetting the risk of excess sodium in the diet with respect to inflammation. Of course, moving towards this diet needs to be done in a slow and consistent way, one that is mindful of dietary intolerances. When on a plant-based diet, it is important to be mindful of protein + mineral-rich choices such as beans, nuts and seeds as protein, zinc and iron are all important for supporting the immune system and gut barrier integrity.

SCD and Low FODMAP Diet for Ulcerative Colitis

There is a lot of interest – but limited clinical evidence – for the use of the specific carbohydrate diet (SCD) and low FODMAP diet for ulcerative colitis. 

In one trial, a low FODMAP diet did appear to improve quality of life and symptoms of ulcerative colitis, without improving fecal calprotectin or C-reactive protein, two markers of inflammation. If you are experiencing a lot of IBS-like symptoms, it may be a temporary option to help get symptoms under control.

I have also used low FODMAP foods as a lower fermentation framework for increasing fruit and vegetable intake for those who are currently eating a low fiber diet. I worry about the adoption of a long-term low FODMAP diet in ulcerative colitis as I believe that it might be simply tamping down symptoms by further altering the gut microbiome…which could be detrimental for long term gut health.

The specific carbohydrate diet is based on a decades-old book called Breaking the Vicious Cycle. To my mind, it is similar to (but not the same as) a low FODMAP approach in that it alters the types of carbohydrates available for fermentation in the gut. 

It is not uncommon for those who have UC to feel that an SCD diet is helping; if that is the case, we will support our client on that chosen path – however, I don’t believe it is a solution for long term gut health and won’t advocate for it in practice. It is a complex diet to follow and isn’t supported by the evidence.

What to eat during an ulcerative colitis flare up

When you’re in a flare, the most important thing to do is follow your doctor’s advice and avoid high fibre, irritating foods. For my clients who are already plant-based, this can take some work to lessen fibre while maintaining your nutrient intake. You may need doctor-supervised bowel rest, where nutrition is provided via other means. Or, you may need a low residue diet until the flare subsides. 

However, you may also be advised to simply eat whatever you can – if this is the case, I find is that so often, the foods chosen are not very healthy and may further the inflammatory response. So here, I recommend juicing small amounts of fruits and vegetables, and enjoying a lot of blended foods like smoothies, blended soups and easy to digest foods like noodles, nut butters, plant-based yogurts and rice.

Supplements for ulcerative colitis

Supplements will play less of a role in healing from ulcerative colitis than you might expect! There are few evidence-informed options here; be sure to talk with your doctor or dietitian before beginning any new supplement.

Vitamin D for Ulcerative Colitis

People with inflammatory bowel diseases are often deficient in vitamin D and low vitamin D levels are associated with disease severity in the research. It is thought that vitamin D has an important role to play in immunity, helping to modulate the inflammatory response. To support bone health, as well as improve outcomes in ulcerative colitis, I recommend taking vitamin D daily. Ask your doctor how much vitamin D they think you should take in order to get your blood levels up over 75 nmol/L. In the absence of that advice, 2000IU Vitamin D3 daily is a safe and conservative dose and vegan options are now available.

Probiotics for Ulcerative Colitis

While the degree of dysbiosis – bacterial imbalance – in those with ulcerative colitis is often not as pronounced as in those with Crohn’s disease, I do recommend that initially my clients trial a probiotic, particularly if they are having more than 3 bowel movements a day. However, I do not recommend that a probiotic be taken without also improving the diet. If poor diet is driving dysbiosis, it’s less likely that a probiotic can create long-lasting change.

The research isn’t extensive, but some supports the use of probiotics as one option to help maintain remission in ulcerative colitis. It is important not to buy just any probiotic that is on sale. There is a huge selection of probiotics on the shelves and many have zero research to prove their efficacy. The probiotic I recommend most often with ulcerative colitis is Visbiome, as it has randomized controlled trials to support its use in ulcerative colitis. My second choice, if Visbiome doesn’t fit the budget or improve symptoms, is Bio-K+ (note, I am a spokesperson for this brand) as it has evidence to suggest that it can help prevent clostridium difficile infection, which is more common in ulcerative colitis. 

There you have it! I hope that this overview of how we approach ulcerative colitis in practice gives you some guidance to pursue your own unique path. If you have questions, just pop them in the comments…and please share this post with anyone you think might benefit! And of course, if you’re ready to get some one-on-one advice for eating with ulcerative colitis, our dietitians are ready to help!

Photo by Monika Grabkowska on Unsplash