IBD Diet: What the Evidence Supports for Crohn's and Colitis

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An IBD diet is not a single plan that controls Crohn's disease or ulcerative colitis, and no diet replaces medical treatment. What the evidence does support is narrower and more practical: a healthy, Mediterranean-style way of eating for most people with inflammatory bowel disease, softer food textures for people with narrowed sections of bowel, specific liquid nutrition therapies for some people with Crohn's disease, and regular checks for malnutrition and vitamin and iron deficiencies. This page walks through that evidence for adults in Arlington, Annandale, and the rest of Northern Virginia who live with IBD, or who were recently diagnosed and are trying to sort useful diet advice from the rest.

This article is general education, not medical advice. Please do not stop, skip, or change an IBD medication because of a diet, and talk with your gastroenterologist before starting any restrictive eating plan.

Why the IBD diet question is so confusing

Food is one of the first things people ask about after an IBD diagnosis, and the answers they find online often conflict. The American Gastroenterological Association (AGA) Clinical Practice Update on diet and nutritional therapies in IBD, published in the journal Gastroenterology in March 2024, opens by acknowledging this: guidance about diet for people with IBD is often controversial and a source of uncertainty for physicians and patients alike.

Part of the confusion is that diet has been studied in two very different ways. One question is whether diet plays a role in who develops IBD in the first place. The other is whether a diet can treat active disease or keep it quiet. The answers are not the same, and a finding about one does not automatically apply to the other.

The AGA update is an expert review rather than a formal guideline. Its authors drew practical advice from the published research combined with expert opinion, and because it was not a systematic review, the statements do not carry formal ratings of evidence quality. It is still the most recent document from a US gastroenterology society focused on this topic, and it is the main source for this page.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) adds a useful starting point for patients: researchers have not found that specific foods cause or worsen Crohn's disease symptoms, and its ulcerative colitis page says the same for ulcerative colitis. Individual foods may still bother an individual person, which is why NIDDK suggests talking with your doctor about foods that seem related to your symptoms and, if your doctor suggests it, keeping a food diary.

The everyday IBD diet: a Mediterranean pattern

The first statement in the AGA update applies to almost everyone with IBD. Unless there is a reason not to, the AGA advises that all patients with IBD follow a Mediterranean diet for their overall health and general well-being. It describes that diet as:

• Rich in a variety of fresh fruits and vegetables
• Rich in monounsaturated fats, such as those in olive oil
• Built on complex carbohydrates and lean proteins
• Low in ultraprocessed foods, added sugar, and salt

The wording matters. The AGA recommends this pattern for overall health. In the same statement it says plainly that no diet has consistently been found to decrease the rate of flares in adults with IBD. A Mediterranean pattern is a sound base for eating well while living with a chronic condition, not a treatment for the inflammation itself.

NIDDK makes a related point about gut bacteria. Some experts believe the microbiome may play a role in Crohn's disease, and NIDDK notes that eating a variety of healthy foods can support healthy bacteria in the gut and that your doctor may recommend eating more fruits and vegetables.

Red and processed meat and ulcerative colitis

One narrow finding stands out in the AGA update. A diet low in red and processed meat may reduce flares of ulcerative colitis, but it has not been found to reduce relapse in Crohn's disease. That fits naturally inside a Mediterranean pattern, which already leans on fish, poultry, beans, and other lean proteins. It is a "may," not a promise, and it does not replace the medication that keeps ulcerative colitis in remission.

IBD diet with strictures: texture matters

Some people with IBD, more often those with Crohn's disease, develop strictures: narrowed segments of intestine caused by inflammation or scarring. For them, the general advice to eat plenty of fruits and vegetables can run into a practical problem. The AGA notes that people with symptomatic strictures may not tolerate fibrous, plant-based foods such as raw fruits and vegetables because of their texture.

The answer the AGA offers is not to give up plant foods altogether. It suggests careful chewing and cooking or processing fruits and vegetables to a softer, less fibrous consistency, which may help people with strictures include a wider variety of plant foods and fiber. Cooked, peeled, pureed, or blended produce often fits that description.

Strictures can cause cramping, bloating, nausea, or vomiting after meals, and a stricture that blocks the bowel is an emergency. If you have Crohn's disease and these symptoms, the texture of your food is a question for your gastroenterologist, who can tell you whether a stricture is present and what is safe for you to eat.

When nutrition is part of Crohn's disease treatment

There is one area where a specific diet does act as treatment, and it applies mainly to Crohn's disease. These therapies are prescribed and supervised, not something to start from a website.

Exclusive enteral nutrition

Exclusive enteral nutrition means getting all of your nutrition from a liquid formula for a period of time, with no regular food. The AGA describes it as an effective therapy for bringing Crohn's disease into clinical remission and improving how the bowel lining looks on endoscopy, with stronger evidence in children than in adults. It says exclusive enteral nutrition may be considered as a bridge therapy that spares a person from steroids.

The AGA also says exclusive enteral nutrition may be effective for people with Crohn's disease who are malnourished before elective surgery, to improve their nutritional status and reduce complications after the operation.

The Crohn's disease exclusion diet

The Crohn's disease exclusion diet is a form of partial enteral nutrition: it combines a liquid formula with a structured list of allowed and excluded foods. According to the AGA, it may be an effective therapy for bringing about clinical remission and endoscopic response in mild to moderate Crohn's disease of relatively short duration. The AGA lists anyone following this diet among the people who should have their care co-managed with a registered dietitian.

Neither therapy has the same standing for ulcerative colitis in the AGA update, and both work alongside the rest of a treatment plan, not in place of it.

IBD diet and malnutrition: the risk that gets missed

The AGA calls malnutrition an underrecognized condition among people with IBD. It can come from the disease itself and from the eating restrictions people place on themselves. NIDDK explains how Crohn's disease affects nutrition: symptoms can reduce appetite, inflammation in the small intestine can reduce how well nutrients are absorbed, and some medicines and surgeries can reduce absorption too.

This is one reason self-directed elimination diets carry risk. Cutting out one food group after another, without a plan, can leave a person eating less overall and missing nutrients at a time when the body needs them.

Screening for malnutrition

The AGA advises that everyone with IBD be screened regularly for malnutrition by looking for signs such as:

• Unintended weight loss
• Swelling (edema) and fluid retention
• Loss of fat and muscle mass

When those signs are present, the AGA says a more complete evaluation by a registered dietitian is indicated. It also notes that blood protein levels are no longer recommended for diagnosing malnutrition, because they are not specific to nutrition and they shift with inflammation. If you have lost weight without trying, our page on unexplained weight loss explains why it deserves attention.

Vitamin D, iron, and vitamin B12

The AGA advises that everyone with IBD be monitored for vitamin D and iron deficiency. People with extensive disease in the ileum (the last part of the small intestine) or prior ileal surgery, such as a resection or an ileal pouch, should also be monitored for vitamin B12 deficiency, because the ileum is where B12 is absorbed.

Iron deficiency is common in IBD, and active inflammation can limit how well oral iron is absorbed. Our page on iron deficiency anemia explains the 2024 AGA iron guidance, including when intravenous iron is advised for people with IBD. NIDDK notes that your doctor may recommend dietary supplements if your body does not absorb enough nutrients, and advises talking with your doctor before taking supplements, vitamins, or complementary therapies.

IBD diet support from a registered dietitian

The AGA describes registered dietitians as an essential part of the team for people with IBD. It advises co-management with a dietitian for everyone with complicated IBD, especially people who have:

• Malnutrition
• Short bowel syndrome
• An enterocutaneous fistula (an abnormal connection between the bowel and the skin)
• More complex nutrition therapy, such as exclusive enteral nutrition, other enteral nutrition, or nutrition by vein
• A Crohn's disease exclusion diet

It also suggests that everyone newly diagnosed with IBD have access to a registered dietitian. If you have not met with one, it is reasonable to ask your gastroenterologist about a referral.

Nutrition by vein and short bowel syndrome

A smaller group of people with IBD need nutrition delivered through a vein, called parenteral nutrition. The AGA describes several situations:

• Short-term parenteral nutrition may be used before surgery when an abscess or inflamed mass in the abdomen limits how much nutrition a person can take by mouth or tube, giving the bowel rest and helping reduce infection and inflammation until surgery.
• The AGA suggests parenteral nutrition for a high-output fistula, a prolonged ileus (when the bowel stops moving food along), short bowel syndrome, and severe malnutrition when eating and tube feeding have been tried and failed or are not possible.
• For people with IBD and short bowel syndrome, the AGA advises moving from long-term parenteral nutrition toward customized hydration (intravenous electrolytes or oral rehydration solutions) and eating by mouth whenever possible, to lower the risk of long-term complications. It notes that a class of medicines called GLP-2 agonists can help with that transition.

These decisions are made by a care team, often including a gastroenterologist, a surgeon, and a dietitian, and usually in a hospital setting at first.

Can diet prevent IBD?

Family members of people with IBD often ask this. The AGA's answer is limited to associations, not proof. Breastfeeding is associated with a lower risk of IBD diagnosis during childhood. A healthy, balanced Mediterranean diet rich in fruits and vegetables, with less ultraprocessed food, has been associated with a lower risk of developing IBD. NIDDK says the same thing in simpler terms: healthier diets appear to be associated with less risk of developing IBD.

An association means people who eat this way develop IBD less often in studies. It does not show that changing your diet will prevent the disease in you or your children.

What the IBD diet evidence does not support

Reading the AGA statements together, a few limits are clear:

• No diet replaces medication. No diet has consistently reduced flares in adults with IBD, and the nutrition therapies that do work in Crohn's disease are supervised treatments used alongside a care plan.
• No single food list fits everyone. NIDDK says researchers have not found that specific foods cause or worsen Crohn's disease or ulcerative colitis. A food that bothers one person may be fine for another.
• Restriction has a cost. Cutting out foods without guidance can contribute to malnutrition, which the AGA says is already underrecognized in IBD.
• Symptoms are not the same as inflammation. Feeling better on a diet does not confirm that the bowel has healed. That is measured with tests and, at times, endoscopy.

Some people with IBD in remission still have bloating, gas, or loose stools that resemble irritable bowel syndrome. Our page on the low FODMAP diet explains how that diet is used for IBS-type symptoms and why it should never stand in for evaluation of inflammation. The AGA IBD update does not make a recommendation on it for IBD, so it is a conversation to have with your gastroenterologist rather than a plan to start alone.

IBD diet questions to bring to your gastroenterologist

An IBD visit is a good time to raise food directly. Questions that tend to be useful:

• Is there anything about my disease, such as a stricture, that should change what I eat or how I prepare it?
• Have my vitamin D and iron levels been checked, and do I need vitamin B12 monitoring?
• Am I losing weight or muscle in a way that suggests malnutrition?
• Would a registered dietitian be helpful for me, and can you refer me to one?
• If I have Crohn's disease, is exclusive enteral nutrition or the Crohn's disease exclusion diet an option for me?
• Are any supplements I take safe with my medications?

Bringing a few weeks of a food and symptom diary can make that conversation more concrete.

Symptoms that should not wait

Diet changes are never a reason to delay care for a flare or a complication. Contact your gastroenterologist promptly for more frequent bloody stools, a return of symptoms after a period of remission, fever, or weight loss you cannot explain. Our pages on blood in the stool and chronic diarrhea explain more. Severe abdominal pain, repeated vomiting, a swollen belly, or being unable to pass stool or gas can signal a blockage: call 911 or go to an emergency department.

IBD care in Northern Virginia with GC of NoVA

Gastroenterology Center of Northern Virginia cares for adults with Crohn's disease and ulcerative colitis across Arlington, Annandale, and the surrounding communities. Our five gastroenterologists can review how your disease is behaving, check for the deficiencies the AGA advises monitoring, talk through how food fits with your treatment, and coordinate with your primary care physician and other members of your care team. Our IBD page covers diagnosis and the general categories of treatment, and our page on your first gastroenterologist visit explains what to bring.

We see patients at our Arlington office at 1715 N George Mason Drive, adjacent to VHC Health, and our Annandale office at 3299 Woodburn Road in the Woodburn Medical complex. To schedule a visit, call Arlington at (703) 522-7476 or Annandale at (703) 560-6106, or learn more at gcofnova.com.

This article is for general education and is not medical advice. Talk with a qualified gastroenterologist about your symptoms, diagnosis, and treatment options.