Scientists reviewed dozens of studies about how different foods affect constipation—that uncomfortable problem where it’s hard to have bowel movements. They found that eating Mediterranean-style foods (like olive oil, vegetables, and fish), plant-based meals, and foods high in fiber can all help your digestive system work better. On the flip side, eating too much fatty food can make constipation worse. The research also shows that special bacteria called probiotics and certain plant compounds can help too. The key takeaway? What you eat directly impacts how well your digestive system functions, and personalized eating plans based on your individual needs might work best.

The Quick Take

  • What they studied: How different types of diets and food ingredients affect constipation and help people have regular, healthy bowel movements
  • Who participated: This was a review of many existing studies, so it combined findings from thousands of people across different research projects rather than studying one specific group
  • Key finding: Mediterranean diets, plant-based diets, and high-fiber foods all help reduce constipation by improving gut bacteria and making bowel movements easier, while high-fat diets tend to make constipation worse
  • What it means for you: You can likely improve constipation by eating more vegetables, fruits, whole grains, and plant-based foods, and by cutting back on fatty foods. However, what works best varies from person to person based on their unique gut bacteria, so you may need to experiment to find what works for you

The Research Details

This research is a comprehensive review, meaning scientists looked at and summarized findings from many different studies about diet and constipation. Instead of doing one new experiment, they analyzed what other researchers had already discovered about how foods like Mediterranean diets, plant-based diets, high-fiber foods, and fatty foods affect constipation. They also examined how special ingredients like probiotics (good bacteria), prebiotics (food for good bacteria), and plant compounds called polyphenols and polysaccharides help with bowel movements.

The researchers organized all this information to understand the ‘why’ behind the results—not just that certain diets help, but how they actually work in your body. They looked at how these foods change the bacteria in your gut, affect your digestive system’s movement, and influence your body’s chemical messengers that control digestion.

This approach is valuable because it brings together evidence from many different studies to give us a bigger picture. Instead of relying on one small study, a review like this shows patterns across hundreds of research projects. This helps doctors and nutritionists give better advice because they can see what consistently works across different groups of people. It also helps identify which specific foods and ingredients are most helpful and explains the science behind why they work.

This review was published in a well-respected scientific journal focused on food research. The strength of this type of research depends on the quality of the studies it reviewed. The findings are based on established scientific evidence, though individual results can vary from person to person. Since this summarizes existing research rather than conducting a new experiment, it’s considered a high-level type of evidence, but readers should know that not all the original studies may have been equally rigorous

What the Results Show

Mediterranean and plant-based diets emerged as the most effective dietary approaches for reducing constipation. These diets work by improving the balance of bacteria in your gut and increasing beneficial compounds called short-chain fatty acids (SCFAs), which help your intestines move food along more efficiently. These diets also reduce inflammation in your digestive system, which can contribute to constipation problems.

High-fiber diets help constipation in a different way: fiber acts like a sponge that holds water in your stool, making it softer and easier to pass. Fiber also feeds the good bacteria in your gut, which then produce gases and SCFAs that help move things along in your intestines. In contrast, high-fat diets had the opposite effect—they were linked to more constipation and unhealthy changes in gut bacteria.

Special supplements like probiotics (live good bacteria) and prebiotics (food for good bacteria) can help relieve constipation by restoring balance to your gut bacteria and increasing helpful compounds. Plant compounds called polyphenols (found in berries, tea, and nuts) help by strengthening your intestinal lining and reducing inflammation. Another plant compound called polysaccharides helps by activating genes that improve how your intestines move and absorb water.

The research identified several important supporting findings. High-fat diets not only change gut bacteria negatively but also reduce the availability of a chemical messenger called serotonin (5-HT) that helps control intestinal movement. Additionally, high-fat diets reduce mucin secretion, which is a protective coating your intestines need. The combination of probiotics and prebiotics together (called synbiotics) appears to work better than either one alone for relieving constipation. The research also emphasizes that individual responses to diet vary significantly based on each person’s unique gut bacteria composition, suggesting that a one-size-fits-all approach to treating constipation through diet may not be optimal.

These findings align with and strengthen previous research showing that fiber helps constipation, but this review provides more detailed explanations of how fiber actually works in your body. The positive effects of Mediterranean and plant-based diets on constipation are consistent with their known benefits for overall digestive health. The research also confirms earlier findings that probiotics can help with constipation, while adding new information about how they work. The negative effects of high-fat diets on constipation have been observed before, but this review explains the specific mechanisms—changes in gut bacteria, reduced serotonin, and decreased protective mucin.

As a review of existing studies, this research is limited by the quality and design of the studies it examined. The review doesn’t provide a specific number of people studied because it combines many different studies with varying sizes and methods. Some dietary interventions may have been studied more thoroughly than others, which could bias the findings. Individual responses to diet vary greatly, so recommendations that work for most people may not work for everyone. The research doesn’t provide clear guidance on exactly how much fiber or which specific foods work best for each person. Additionally, most studies on this topic have been conducted in developed countries, so findings may not apply equally to all populations worldwide

The Bottom Line

If you struggle with constipation, consider gradually increasing fiber intake through whole grains, vegetables, fruits, and legumes (moderate to strong evidence). Adopting a Mediterranean-style diet or increasing plant-based foods may help (moderate evidence). If dietary changes alone don’t work, probiotics or prebiotic supplements may provide additional benefit (moderate evidence). Reduce high-fat foods, which appear to worsen constipation (moderate evidence). Drink plenty of water, especially when increasing fiber intake. Work with a healthcare provider or dietitian to develop a personalized plan based on your specific needs and gut bacteria composition, as individual responses vary significantly

Anyone experiencing constipation should consider these dietary approaches as a first-line treatment before turning to medications. People with chronic constipation, irritable bowel syndrome, or digestive disorders may find this especially helpful. However, people with certain medical conditions (like severe inflammatory bowel disease) should consult their doctor before making major dietary changes. Those with food allergies or intolerances need to adapt these recommendations to their specific situation. Older adults and people taking certain medications that cause constipation may benefit from these dietary strategies

Most people see improvements in bowel regularity within 1-2 weeks of increasing fiber intake, though it may take 4-6 weeks to see full benefits as your gut bacteria adjust. Probiotic supplements may show effects within 2-4 weeks. Dietary pattern changes like switching to Mediterranean or plant-based eating may take 4-8 weeks to show noticeable improvement. Individual timelines vary significantly based on the severity of constipation and how well your body responds to dietary changes

Want to Apply This Research?

  • Track daily bowel movements (frequency and ease on a 1-10 scale), daily fiber intake in grams, and water consumption in ounces. Also note which specific foods or meals seem to help or worsen constipation to identify personal patterns
  • Use the app to set a daily fiber goal (gradually increasing to 25-35 grams per day) and log meals to monitor progress. Set reminders to drink water throughout the day and track which foods from Mediterranean or plant-based categories you’re eating. If using probiotics, log when you take them and note any changes in bowel regularity
  • Create a weekly summary showing bowel movement frequency, average ease rating, fiber intake trends, and correlation with specific foods or supplements. Use this data to identify which dietary changes work best for your individual body, and share patterns with your healthcare provider to refine your personalized approach over time

This review summarizes scientific research about diet and constipation but is not a substitute for professional medical advice. Constipation can have many causes, including medical conditions and medications, so consult your doctor or registered dietitian before making significant dietary changes, especially if you have chronic constipation, inflammatory bowel disease, or other digestive disorders. Individual responses to dietary interventions vary significantly. If constipation persists despite dietary changes, seek medical evaluation to rule out underlying conditions. Always discuss new supplements, including probiotics and prebiotics, with your healthcare provider, particularly if you take medications or have compromised immune function.