For years it has been known that increasing the amount of fiber (and drinking enough fluids) in a person's diet helps to prevent constipation. A recent large multi-year study of 96,000 adults confirmed this: Mediterranean and plant-based diets prevented constipation, and Western and inflammatory diets (low fiber, high ultra-processed foods) raised constipation risk.
Vegetables, cruciferous vegetables (e.g., broccoli), legumes (beans, lentils, chickpeas), and fruits were all associated with reduced risks for constipation. High vegetable and nut consumption was especially good for preventing constipation. Additionally, a low carbohydrate diet showed a slight increased risk for constipation. Eating a diet rich in cereal fibers (e.g., white bread, low fiber breakfast cereals) and ultra-processed foods was linked to constipation.
Besides reducing constipation, many studies show that eating a diet rich in fruits, vegetables, whole grains, seeds, nuts, legumes, such as the Mediterranean diet, is protective for cardiometabolic diseases (e.g., heart disease, heart attack, strokes, kidney disease, and type 2 diabetes), cancer, and even early death. This type of diet is high in fiber, has positive effects on the gut microbiome, and reduces chronic inflammation.
From Science Daily: What 96,000 adults taught scientists about preventing constipation
Chronic constipation becomes more common with age. Researchers from Mass General Brigham conducted a new study examining whether five widely followed diets could help prevent chronic constipation in middle- and older-age adults. The team monitored more than 96,000 participants for several years to see how long-term eating habits influenced the likelihood of developing this persistent gastrointestinal issue. Their analysis showed that people who routinely ate a Mediterranean or plant-based diet experienced a lower incidence of constipation. The findings appear in Gastroenterology.
"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 healthcare system. "Our findings suggest that as we age, certain healthy diets may provide benefits to our gut beyond the known cardiovascular benefits."
Previous research has demonstrated that healthy diets can ease constipation symptoms, but this study is the first to show that some diets may actually prevent chronic constipation from developing. "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," said Staller.
Using information from the Nurses' Health Study, Nurses' Health Study II and the Health Professionals Follow-Up Study, the investigators evaluated long-term dietary patterns in middle- and older-age adults and identified who later experienced chronic constipation, which was defined as symptoms lasting at least 12 weeks within a year. The study assessed five diets: the Mediterranean diet, plant-based diet, low-carb diet, Western diet and inflammatory diet. Participants who consistently consumed a Western or inflammatory diet were more likely to develop chronic constipation, while those who followed a low-carb diet did not show a strong effect on constipation risk.