A long-term study of more than 96,000 middle- and older-aged adults found that Mediterranean-style and plant-based eating patterns were associated with a lower risk of developing chronic constipation, even after accounting for fiber intake. Diets characterized as Western or pro-inflammatory were linked to a higher risk, while low-carbohydrate diets showed little effect.
Researchers from Mass General Brigham analyzed long-term dietary patterns in more than 96,000 participants drawn from three large U.S. cohorts: the Nurses' Health Study, Nurses' Health Study II, and the Health Professionals Follow-Up Study. Over several years of follow-up, they examined how usual eating habits were associated with the likelihood of developing chronic constipation, defined as symptoms persisting for at least 12 weeks in a year.
The study compared five dietary patterns: a Mediterranean-style diet, a plant-based diet, a low-carbohydrate diet, a Western diet high in red and processed meats and refined grains, and a pro‑inflammatory diet rich in ultra-processed foods. Participants whose eating patterns most closely resembled Mediterranean or plant-based diets had a lower incidence of chronic constipation, while those adhering to Western or inflammatory diets had a higher risk. Low-carbohydrate diets showed minimal association with constipation risk.
"Chronic constipation affects millions of people and can significantly impact a patient's quality of life," said senior author Kyle Staller, MD, MPH, of the Division of Gastroenterology at Massachusetts General Hospital, a founding member of the Mass General Brigham health care system, according to a Mass General Brigham release. "Our findings suggest that as we age, certain healthy diets may provide benefits to our gut beyond the known cardiovascular benefits."
The researchers reported that the apparent protective effects of healthier eating patterns were not explained solely by how much fiber people consumed. "We have always assumed that the benefits of eating a healthy diet would be driven by fiber, but our analyses showed the benefit of these healthy diets on constipation were independent of fiber intake," Staller said in the same statement.
"Our findings suggest a diet rich in vegetables, nuts and healthy fats may help prevent chronic constipation in middle- and older-age adults," Staller added. The authors note that prior research has shown that healthy diets can ease constipation symptoms, but this analysis is among the first to demonstrate that specific long-term dietary patterns are associated with a lower risk of chronic constipation developing in the first place.
The findings were published online in 2025 in the journal Gastroenterology under the title "Dietary Patterns and Incident Chronic Constipation in Three Prospective Cohorts of Middle- and Older-aged Adults." According to coverage of the study by HealthDay and Harvard Health Publishing, the research team was led by Yiqing Wang, PhD, of Massachusetts General Hospital, with co-authors including Andrew T. Chan, MD, MPH, and Kyle Staller, MD, MPH. The work was supported in part by funding from the U.S. National Institutes of Health.
