Mediterranean diet linked to reduced risk of inflammatory bowel disease

A review highlights the potential benefits of nutrients like omega-3 fatty acids, polyphenols, and plant-based proteins for IBD management, emphasizing the need for further research to personalize treatments.

Study: The Key Nutrients in the Mediterranean Diet and Their Effects in Inflammatory Bowel Disease: A Narrative Review. Image Credit: Uriya Ganor/Shutterstock.com

In a recent review published in Nutrients, researchers explored how specific nutrients abundant in the Mediterranean diet (MD) affect the gut microbiome and the management of inflammatory bowel diseases (IBD).

They found that MD is linked to a lower risk of chronic diseases such as IBD, and the plant-derived proteins, omega-3 fatty acids, polyphenols, chitosan, resveratrol, and fructo-oligosaccharides (FOS) may support these benefits.

Background

The gut microbiome, comprising microorganisms that colonize the human gut, plays a key role in IBD, such as Crohn’s disease (CD) and ulcerative colitis (UC). Disruptions in the microbiome can damage the intestinal wall and cause inflammation, causing symptoms like abdominal pain, weight loss, and diarrhea.

Diet appears to be a promising way to manage IBD by modulating the community of gut microbiota. The MD, which is high in olive oil, nuts, legumes, whole grains, vegetables, fruits, and fiber and low in animal fats and processed foods, has been linked to reduced IBD risk and better gut health.

This diet promotes beneficial gut bacteria that produce short-chain fatty acids (SCFAs), which support a healthy gut environment. In contrast, Western diets that are high in processed foods can negatively affect the microbiome and intestinal barrier.

Clinical evidence supports the MD for IBD management and prevention, as it is less restrictive and encourages adherence in the long term. However, the specific mechanisms of how the MD affects the gut microbiome in individuals with IBD remain unclear.

The authors conducted a literature search on PubMed using specific terms related to the MD, gut microbiome, and IBD, focusing on preclinical data from articles published from 2019 to 2024.

Carbohydrates, proteins, and fats

Carbohydrates, including prebiotics like inulin, β-glucans, and FOS, have been examined for their potential benefits in IBD by promoting the growth of beneficial gut bacteria, such as Bifidobacteria and Lactobacilli, which may help alleviate symptoms.

Some studies showed positive effects on intestinal permeability and gut microbiota composition in patients CD, while others reported no clinical improvements with FOS.

Interestingly, more restrictive carbohydrate diets may improve inflammation in CD in pediatric populations, though the MD has shown similar or better effects.

In UC, prebiotics like galacto-oligosaccharides (GOS) were found to normalize the microbiota without improving clinical outcomes, indicating the need for more robust clinical trials.

Other compounds, such as chitosan, native starches, and polyphenols from fruits like cranberries, have demonstrated the potential to improve gut health in animal models. Chitosan, in particular, is being explored for its safe long-term use in IBD therapy.

Proteins in the MD, particularly plant-based proteins, show anti-inflammatory effects, while animal proteins from red and processed meats may exacerbate IBD symptoms.

Kefir, a fermented dairy product, has gained attention for its ability to modulate the gut microbiota and improve IBD symptoms in humans. Some amino acids, like tryptophan, are being studied for their role in IBD pathophysiology, with promising findings linking tryptophan metabolism to immune response regulation.

The MD’s fats, mainly unsaturated fats like olive oil, have shown protective effects against inflammation and IBD symptoms.

Omega-3 fatty acids, commonly found in fish and plant sources, also have anti-inflammatory properties, though the evidence in humans remains inconclusive. In general, dietary fats play a significant role in modulating IBD, and further research is needed to refine recommendations for IBD management.

Other important nutrients

The MD includes various plant-derived nutrients that have anti-inflammatory, antioxidant, and gut health benefits.

Quercetin, found in fruits and vegetables like onions, berries, and grapes, has protective effects against oxidative stress and inflammation. It can promote gut health by increasing beneficial bacteria and enhancing intestinal cell regeneration.

Astaxanthin from seafood is another powerful antioxidant with anti-inflammatory properties, while lycopene from tomatoes helps reduce inflammation and maintain intestinal integrity.

Curcumin, found in turmeric, and epigallocatechin gallate (EGCG) from green tea also show promise in reducing inflammation and oxidative stress.

Vitamin D, important for gut health, is often low in IBD patients but can be better absorbed through the MD. Though individual compounds are beneficial, the MD’s combination of nutrients may work synergistically to support gut health and reduce inflammation, especially in IBD.

Conclusions

The MD offers a multifaceted approach to managing inflammation in IBD through beneficial compounds that influence gut microbiota and the intestinal environment.

American guidelines suggest this diet for patients in remission or with mild symptoms. It has fewer harmful additives, like emulsifiers, that may worsen IBD.

While clinical evidence is limited, studies indicate the diet’s potential to support IBD treatments, including fecal microbiota transplantation. However, adherence can be challenging due to gastrointestinal symptoms and psychological factors.

Future research should focus on personalized dietary strategies, including preclinical studies and clinical trials, to optimize treatment for IBD patients based on genetics, microbiome, and lifestyle factors.