Key Points
A large study of more than 96,000 adults found that people who follow a Mediterranean or plant-based diet have a significantly lower risk of chronic constipation compared to those who follow a Western or inflammatory diets.
These plant-forward eating patterns promote regularity by providing fermentable fibers, antioxidants, and plant compounds that support a healthy gut microbiome and softer stools.
Experts note that while fiber helps, whole foods offer additional bioactive compounds that improve gut health more effectively than supplements, and long-term consistency is key for lasting results.
No one likes talking about being constipated, but chances are, it’s happened at least once in your life. Fortunately, what you eat (or don’t eat) can play a big role in keeping you regular, and new research found that two specific diets are associated with a lower risk of chronic constipation.
The study out of Harvard and Mass General Brigham — published in Gastroenterology — analyzed the dietary and bowel habits of more than 96,000 adults participating in one of three long-term studies. Researchers then examined five diets: the Mediterranean diet, a plant-based diet, a low-carb diet, and two diets high in processed foods, red meat, sugar, and saturated fats — the Western diet and the inflammatory diet.
It was then found that people who regularly ate a Mediterranean or plant-based diet had a lower risk of constipation. More specifically, the Mediterranean diet was linked to a 16% lower risk, while a plant-based diet was associated with a 20% lower risk. On the flip side, those who ate a Western or inflammatory diet had a higher risk of chronic constipation, at 22% and 24%, respectively. (FYI: chronic constipation was defined as having a bowel movement every three or more days for 12 or more weeks in the past year.)
The findings are notable, but there are a few things to keep in mind. First, the study was observational, so confounding factors (such as gender, socioeconomic status, and medication use) may be involved. Also, the study participants were older, white health professionals with multiple health conditions, which limits how widely the results can be applied to the general population, says Leybelis Padilla, MD, a gastroenterologist, lifestyle medicine physician, and founder of Unlocking GI. Even so, the findings add to strong evidence supporting the benefits of eating more whole foods — especially plant-based foods — for improving constipation.
So, how exactly can these diets help you stay regular? We asked three gastroenterologists.
Which diets were found to reduce the risk of chronic constipation?
The study found that people who followed a Mediterranean-style or plant-based diet had a lower risk of developing chronic constipation, whereas diets high in ultra-processed foods and red meat were linked to a higher risk. (A Mediterranean diet focuses on plant-based foods, with moderate amounts of fish, poultry, and dairy, and very limited red meat and sweets.)
More specifically, higher intakes of vegetables (especially tomatoes, cruciferous varieties, and leafy greens), nuts, and healthy fats (all staples of a Mediterranean diet) were linked to a lower risk of constipation — even after accounting for total fiber intake. “This is important because fiber alone is often seen as the gold standard for digestive health, yet these findings highlight that whole foods matter more than fiber supplements,” Padilla says. “Whole foods provide bioactive compounds, like probiotics, antioxidants, and polyphenols, that work together to support the gut microbiome in ways supplements can’t replicate,” she explains.
So how and why do plant-forward diets support regular digestion? According to Supriya Rao, MD, a quadruple board-certified physician in internal medicine, gastroenterology, obesity medicine, and lifestyle medicine, these diets naturally provide fermentable fiber, water-rich foods, and plant compounds that keep stools soft and the gut functioning.
Plant-based diets are also known to nourish beneficial gut bacteria. These microbes then ferment fiber into compounds — like short-chain fatty acids — that influence gut motility and fluid balance, resulting in softer stools and more consistent bowel movements, Rao explains.
Related: New Research Pinpoints the 3 Most Effective Foods for Relieving Constipation
Short-chain fatty acids also support intestinal health by maintaining gut barrier integrity, which reduces inflammation, improves colonic transit, and minimizes the risk of constipation, adds Patrick Amar, MD, a gastroenterologist and internal medicine physician at Holy Cross Medical Group.
Interestingly, the study also found that wine intake was linked to reduced constipation risk. However, this effect is likely attributable to alcohol’s inherent toxic effects on the gut, which can induce diarrhea and thereby indirectly relieve constipation, Padilla says.
Does following a plant-based or Mediterranean diet improve overall gut health?
Generally speaking, yes. “Plant-based or Mediterranean diets increase the availability of fermentable plant compounds that encourage the growth of microbes involved in fiber breakdown and short-chain fatty acid production, which in turn can promote softer stools and more regular bowel movements,” Rao says.
Amar also notes that the anti-inflammatory properties of plant-forward diets may improve bowel function by enhancing gut motility, strengthening the intestinal barrier, and increasing mucin secretion (a gel-forming protein that is the main component of mucus lining the gastrointestinal tract), thereby easing stool passage.
That said, Rao emphasizes that gut health is highly individualized, so plant-forward diets may not work for everyone, particularly those with conditions like irritable bowel syndrome. “Constipation can reflect low fiber and poor diet, but it’s not purely just a nutrition issue, because medications, hormones, pelvic floor issues, and medical conditions also play a role,” she explains. As a result, effective constipation treatment often requires a personalized approach rather than a one-size-fits-all dietary solution.
Foods that worsen constipation
Diets low in whole plant foods and high in ultra-processed foods — commonly called the Standard American Diet (SAD) — are linked to constipation, Rao says. Excessive sugar, refined grains, saturated fats, and low-fiber diets can also contribute to sluggish bowel movements, she adds. If you want to stay regular and/or relieve constipation, try cutting back on the following foods:
Refined sugar (cakes, candy, ice cream, sweetened drinks, soda)
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 a plant-forward diet ease constipation?
It depends. Some improvements in bowel regularity may appear within one to two weeks of adopting a plant-based or Mediterranean diet, but long-term benefits — like healthier gut bacteria, reduced inflammation, and a stronger gut barrier — require sustained dietary changes, as suggested by this multi-year study, Amar says. In other words, consistency is key, so long-term adherence to a plant-forward diet matters most.
Related: The Difference Between Prebiotics and Probiotics — and Which Foods to Eat for Each
Just don’t overdo consuming fiber too quickly. Adding too much to your diet at once can cause bloating, gas, and abdominal discomfort if your system isn’t used to it, so Amar advises gradually introducing fiber and more plant foods over several weeks to give your gut time to adjust.
Reviewed by
Lauren Manaker MS, RDN, LD, CLEC: Lauren is an award-winning registered dietitian and three-time book author, with more than 22 years in the field.
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