Mediterranean and Plant-Based Diets Linked to Lower Risk of Chronic Constipation

Dealing with constipation is unpleasant, and its prevalence increases with age. Fortunately, research suggests that dietary choices can significantly impact bowel regularity. A large study of over 96,000 adults has found that following a Mediterranean or plant-based diet is associated with a substantially lower risk of developing chronic constipation compared to those who consume Western or inflammatory diets.

How Diet Impacts Constipation Risk

The study, published in Gastroenterology and conducted by researchers at Harvard and Mass General Brigham, analyzed the dietary habits and bowel movements of participants over several years. Researchers categorized participants based on their adherence to five different dietary patterns: a Mediterranean diet, a plant-based diet, a low-carbohydrate diet, a Western diet, and an inflammatory diet.

The results showed a clear correlation between diet and constipation risk:

• Mediterranean Diet: Linked to a 16% lower risk of chronic constipation.
• Plant-Based Diet: Associated with a 20% lower risk of chronic constipation.
• Western Diet: Increased the risk of chronic constipation by 22%.
• Inflammatory Diet: Increased the risk of chronic constipation by 24%.

Chronic constipation was defined as having a bowel movement every three or more days for 12 or more weeks in the past year.

Why Plant-Forward Diets Promote Regularity

These plant-focused eating patterns support regularity through several mechanisms. They provide fermentable fibers, antioxidants, and plant compounds that nurture a healthy gut microbiome and contribute to softer stools. According to Supriya Rao, MD, a physician specializing in gastroenterology and lifestyle medicine, these diets naturally offer fermentable fiber, water-rich foods, and plant compounds that maintain stool softness and optimal gut function. Harvard Health Publishing

Plant-based diets nourish beneficial gut bacteria, which ferment fiber into short-chain fatty acids. These compounds influence gut motility and fluid balance, leading to softer stools and more consistent bowel movements. Short-chain fatty acids as well bolster intestinal health by maintaining gut barrier integrity, reducing inflammation, improving colonic transit, and minimizing constipation risk.

The Role of Bioactive Compounds

While fiber is important, experts emphasize that whole foods offer benefits beyond fiber content. Leybelis Padilla, MD, a gastroenterologist and lifestyle medicine physician, explains that whole foods provide bioactive compounds – like probiotics, antioxidants, and polyphenols – that support the gut microbiome in ways supplements cannot replicate. Food & Wine

What to Limit for Optimal Gut Health

Diets high in ultra-processed foods, red meat, sugar, and saturated fats – often referred to as the Standard American Diet (SAD) – are linked to constipation. Excessive consumption of these foods can lead to sluggish bowel movements. Consider reducing your intake of:

• Swift food
• Refined sugar (cakes, candy, ice cream, sweetened drinks, soda)
• Fried foods
• Processed snacks (chips, sugary cereal, flavored crackers, instant noodles)
• Processed meat (hot dogs, bacon, pepperoni, deli meats)
• Refined grains (white bread, white rice, pastries)
• Saturated fats (butter, cream, sausage, beef tallow, mayonnaise)

How Quickly Can You Expect Results?

Some improvements in bowel regularity may be noticeable within one to two weeks of adopting a plant-based or Mediterranean diet. However, long-term benefits – such as a healthier gut microbiome, reduced inflammation, and a stronger gut barrier – require sustained dietary changes. Consistency is key, and gradual introduction of fiber is recommended to avoid bloating, gas, and abdominal discomfort.

Important Considerations

It’s important to note that the study was observational, meaning it cannot definitively prove cause and effect. The study participants were primarily older, white health professionals, which may limit the generalizability of the findings. Gut health is also highly individualized, and plant-forward diets may not be suitable for everyone, particularly those with conditions like irritable bowel syndrome. Constipation can be influenced by factors beyond diet, including medications, hormones, pelvic floor issues, and underlying medical conditions.

Reviewed by Lauren Manaker MS, RDN, LD, CLEC