Ulcerative colitis is a long-term condition that causes inflammation in the colon and rectum. Scientists are discovering that what you eat plays a big role in managing this disease. This review looked at how different foods and nutrients affect ulcerative colitis symptoms and inflammation. The research shows that eating more fiber, fish, and Mediterranean-style foods can help reduce inflammation, while eating lots of processed meats and ultra-processed foods can make things worse. The study also found that many people with ulcerative colitis don’t get enough important vitamins and minerals like vitamin D and iron, which should be checked regularly.

The Quick Take

  • What they studied: How different foods, nutrients, and eating patterns affect ulcerative colitis—a chronic bowel disease that causes inflammation and digestive problems.
  • Who participated: This was a review of existing research, not a new study with participants. Scientists looked at many previous studies to understand what we know about diet and ulcerative colitis.
  • Key finding: Eating a Mediterranean-style diet (lots of vegetables, fish, olive oil, and whole grains) appears to reduce inflammation and disease activity, while eating processed meats and ultra-processed foods seems to make inflammation worse.
  • What it means for you: If you have ulcerative colitis, working with a dietitian to eat more whole foods and fewer processed foods may help control your symptoms. However, everyone’s body is different, so what works best for you should be personalized to your needs and preferences.

The Research Details

This is a narrative review, which means scientists read and summarized many different research studies about diet and ulcerative colitis to understand what we currently know. Instead of doing one new experiment, the researchers looked at the big picture of existing evidence to identify patterns and important findings.

The review examined how three main things affect ulcerative colitis: specific nutrients (like fats and fiber), food additives (chemicals added to processed foods), and overall eating patterns (like Mediterranean diet or low-FODMAP diet). The researchers looked at how these dietary factors influence the disease in multiple ways—by changing gut bacteria, affecting the intestinal lining, and controlling inflammation.

This type of review is useful because it brings together information from many studies to give a complete picture of what we know. However, it’s based on summarizing other people’s work rather than collecting new data directly.

Understanding how diet affects ulcerative colitis is important because it’s one of the few things patients can actually control. Unlike genetics (which you can’t change), diet is something you can modify every day. If we can identify which foods help and which hurt, people with ulcerative colitis can make better choices to manage their symptoms without always relying on medications.

This review was published in a respected medical journal, which means it was checked by experts before publication. However, because it’s a review of other studies rather than new research, its strength depends on the quality of the studies it examined. The review is honest about areas where we need more research, which is a good sign. Readers should know that some of the studies reviewed may have been small or had limitations, so not all findings are equally strong.

What the Results Show

The research shows that certain foods and eating patterns have clear effects on ulcerative colitis. Foods high in saturated fat (like butter and fatty meats), red meat, and processed meats appear to promote harmful changes in gut bacteria and increase inflammation in the intestines. In contrast, foods rich in fiber (like vegetables, fruits, and whole grains), resistant starches (found in cooled potatoes and beans), and omega-3 fatty acids (found in fish and flaxseed) seem to protect the intestinal lining and reduce inflammation.

The Mediterranean diet—which emphasizes vegetables, fruits, whole grains, fish, and olive oil—showed particularly promising results. People following this diet had less disease activity, more diverse and healthy gut bacteria, and fewer complications. This diet appears to work because it combines many anti-inflammatory foods while avoiding processed foods.

The review also found that many people with ulcerative colitis have low levels of important nutrients including iron, vitamin D, zinc, and magnesium. These deficiencies can make symptoms worse and should be checked regularly and corrected with supplements if needed.

The low-FODMAP diet (which limits certain carbohydrates) can help reduce bloating and digestive discomfort in some people with ulcerative colitis, but it doesn’t appear to reduce the underlying inflammation. Additionally, this diet may reduce beneficial bacteria in the gut, so it shouldn’t be used long-term without professional guidance. In cases where people can’t eat normally due to severe disease, special nutrition given through a vein (parenteral nutrition) can be helpful temporarily. The review emphasizes that a personalized approach—where a nutrition specialist works with each patient based on their specific needs, cultural background, and preferences—is more likely to succeed than a one-size-fits-all diet.

This review builds on previous research by bringing together what we know about multiple dietary factors in one place. Earlier studies have shown links between diet and inflammatory bowel disease, but this review provides a more complete picture of which specific foods help or hurt, and why. The findings about the Mediterranean diet and the problems with processed foods align with what other recent research has shown. However, the review notes that we still need more long-term studies to fully understand how diet affects ulcerative colitis over months and years.

This review has several important limitations. First, because it summarizes other studies rather than conducting new research, it’s only as good as those studies. Some of the studies reviewed were small or had design problems. Second, most research on diet and ulcerative colitis has been done in developed countries, so we don’t know if the findings apply to people in other parts of the world with different foods and genetics. Third, ulcerative colitis affects different people differently, so a diet that works well for one person might not work for another. Finally, the review notes that we need more research on how long people need to follow these diets to see benefits and whether the benefits last over time.

The Bottom Line

If you have ulcerative colitis, consider working with a registered dietitian to: (1) Eat more whole foods like vegetables, fruits, fish, and whole grains while reducing processed meats and ultra-processed foods (high confidence); (2) Consider following a Mediterranean-style eating pattern, which has the strongest evidence for reducing inflammation (moderate to high confidence); (3) Get your vitamin D, iron, zinc, and magnesium levels checked and supplement if needed (high confidence); (4) Avoid the low-FODMAP diet as a long-term solution unless specifically recommended by your doctor for symptom management (moderate confidence). These recommendations should be personalized to your individual needs and preferences.

These findings are most relevant for people who have been diagnosed with ulcerative colitis and want to manage their symptoms through diet. People with other types of inflammatory bowel disease (like Crohn’s disease) may benefit from similar approaches, but the evidence is strongest for ulcerative colitis specifically. Family members of people with ulcerative colitis might also benefit from eating more Mediterranean-style foods for general health. People without ulcerative colitis don’t need to follow these specific recommendations, though eating less processed food is good for everyone.

Changes in diet typically don’t produce immediate results. Most people need to follow dietary changes for at least 4-8 weeks to notice improvements in symptoms. Some benefits, like changes in gut bacteria, may take even longer—sometimes 8-12 weeks or more. The best approach is to make gradual changes and track how you feel over time, working with your healthcare team to adjust as needed.

Want to Apply This Research?

  • Track daily intake of anti-inflammatory foods (servings of vegetables, fish, whole grains) and pro-inflammatory foods (processed meats, ultra-processed foods) alongside symptom severity scores (pain, bowel movements, energy levels) to identify personal patterns over 2-4 week periods.
  • Set a weekly goal to add one Mediterranean-style meal (like fish with vegetables and olive oil) and replace one processed food item with a whole food alternative. Use the app to plan meals, create shopping lists, and log what you eat to build awareness and consistency.
  • Monthly review of symptom patterns correlated with dietary choices to identify personal trigger foods and beneficial foods. Quarterly check-ins with your healthcare provider to monitor nutrient levels (vitamin D, iron, zinc, magnesium) and adjust supplementation as needed based on blood tests.

This review summarizes scientific research about diet and ulcerative colitis but is not a substitute for medical advice. Ulcerative colitis is a serious medical condition that requires ongoing care from a gastroenterologist. Before making major dietary changes, especially if you’re taking medications or have severe symptoms, consult with your doctor or a registered dietitian who specializes in inflammatory bowel disease. Dietary changes should complement, not replace, medical treatment prescribed by your healthcare provider. Individual responses to diet vary significantly, and what works for one person may not work for another.