- Inflammatory bowel disease (IBD) is an umbrella-term that covers several conditions affecting the intestines, including Crohn’s disease and ulcerative colitis.
- It occurs when the immune system mistakenly attacks cells in the bowel, causing inflammation and symptoms such as pain, changes in bowel movements and weight loss.
- People with IBD can often relieve their symptoms by modifying their diet, excluding certain foods and including others.
- Now, a study has found that a plant-based diet made up of mainly nutrient-dense plant foods may help reduce the risk of developing IBD and reduce the need for surgery in those who have the condition.
Inflammatory bowel disease (IBD) describes many long-term conditions that affect the intestines and lead to a range of digestive symptoms.
Around the world, in 2019, there were around 5 million people living with the condition, which is more common in women and is usually diagnosed before the age of 30.
The two main types of IBD are:
- ulcerative colitis, which causes inflammation in the large intestine, usually the colon
- Crohn’s disease, linked to inflammation in any part of the digestive tract but most frequently in the end of the small intestine and the large intestine.
Both types cause a number of symptoms, which may include pain, diarrhea, fatigue, nausea, weight loss, lack of appetite, intestinal bleeding and anemia. The symptoms tend to flare up for short periods of time then go into remission.
Although there is currently no cure for IBD, several treatments, such as anti-inflammatories (
Sometimes surgery is required to remove severely affected parts of the intestine.
Modifying diet can help control symptoms for some people. Dietary changes that may help include:
- keeping a food diary to track whether certain foods lead to symptoms
- limiting intake of dairy products
- restricting intake of unhealthy fats and increasing omega-3 fats
- avoiding or limiting spicy foods, caffeine, and alcohol
- limiting high fiber foods, particularly if the bowel has narrowed
- frequent small meals instead of fewer large ones
- drinking plenty of water
- taking vitamin and mineral supplements to prevent deficiencies.
Now, a study has found that eating a healthy plant-based diet may both reduce the risk of developing IBD, and reduce the need for surgery in those already diagnosed with the condition.
The study, published in
Researchers found that those who adhered to a healthy plant-based diet had a lower risk of IBD, whereas those eating an unhealthy plant-based diet (high in processed plant foods) showed an increased risk of the conditions.
Kelsey Costa, MS, RDN, a registered dietitian nutritionist and owner of Impactful Nutrition, not involved in the study, explained for Medical News Today that “this observational study analyzed data from two large cohorts, strengthening the validity of findings through its size and methodologies.”
“However,” Costa pointed out, “the participants were predominantly European and white adults, limiting the applicability of results to other populations.”
“The study explored important IBD outcomes like surgery, comorbidities, and death. But, it overlooked key aspects like disease activity, relapse rates, and quality of life — these are critical factors that future research should address.”
– Kelsey Costa, MS, RDSN
Plant-based diets may be healthful, including lots of fresh fruit and vegetables, and little processed food or additives.
However, the researchers emphasize that many plant-based products are highly processed, such as meat substitutes and refined plant oils, which may dilute the Health-benefits of traditional plant-based diets if they are not properly accounted for.
For this study, they identified three types of plant-based diets:
- overall plant-based, which included all healthy and unhealthy plant foods
- healthy plant-based, in which nutrient-dense plant foods — whole grains, fruits, vegetables, nuts, legumes and vegetarian protein alternatives, as well as tea and coffee — were positively scored, while refined grains, potatoes/fries, sugary drinks, fruit juices and desserts gained negative scores
- unhealthy plant-based, with positive scores for less nutritious plant foods, and negative scores for healthier plant-based options.
In all cases, highest intake scored 5 points and lowest scored 1.
The researchers also scored a healthy omnivorous diet, with positive scores given to healthy animal products such as dairy, eggs, fish and seafood, for sensitivity analysis.
Ashkan Farhadi, MD, a board-certified gastroenterologist at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, who was not involved in the study, pointed out some of the difficulties of investigating the Health effects of diet.
“There’s a limitation in all nutritional studies, particularly longitudinal,” Farhadi told us.
He also noted: “It’s really hard to define diets. When people say what they are eating, they may also be eating other things. Things may change during the course of a longitudinal study. They may eat cookies for 6 years, then change to the Mediterranean diet and report that!”
However, he added that “the good thing about this study is that they pulled a huge amount of data.”
The researchers concluded:
“In two large cohorts covering more than 500,000 participants across [eight] nations, we found that a Healthy [plant-based diet] was inversely associated with IBD incidence and IBD-related surgery, whereas an unHealthy [plant-based diet] was positively associated with the same outcomes.”
Costa commented on this finding, saying that “the results indicate that a ‘healthy omnivorous diet,’ which includes plants, dairy, eggs, and fish or seafood, may have a slightly stronger association with IBD prevention after accounting for dietary fiber intake.”
“This implies that the protective effects of a healthy plant-based diet against IBD might not only come from fiber but potentially other factors as well. But, it doesn’t necessarily mean one diet is better than the other; both may offer benefits through different mechanisms,” she explained.
“More research is needed to fully understand the impact of different diets on IBD risk and disease course, but we can say without doubt that a healthy diet rich in nutrient-dense, plant-based foods is essential,” Costa added.
In addition, in people already diagnosed with IBD, the healthy plant-based diet reduced the likelihood of the condition becoming more severe and requiring surgery.
“It is very encouraging to see that it [a healthy plant-based diet] not only helps prevent the disease, but slows it down or halts progression to severe cases. That’s a very interesting finding.”
– Ashkan Farhadi, MD
Previous studies have suggested that a vegan, but not a vegetarian diet may be linked to lower levels of inflammatory markers, and in this study the researchers suggest that the beneficial effects of a healthy plant-based diet may be partially, but not entirely, mediated by inflammation.
The researchers also observed that benefits may be greater for participants with a moderate or high genetic risk of developing IBD.
Farhadi told Medical News Today that the gut microbiome could be the mediator between diet and inflammation.
“One theory is that when you are eating refined plant-based foods, you are feeding particular microbes and changing the gut flora. When there is dysbiosis — a disturbed ratio in the microbiome — we see illness,” he said.
“Unrefined foods encourage another group in the microbiome. By using nonprocessed plant-based foods we may be improving the beneficial microbiome population,” Farhadi explained.
