Beans, beans are good for your heart
Despite the fact that legumes like kidney beans and lentils are linked to lower risk of heart disease and some cancers, many people don’t eat them for fear of increased gas. But a new study from the US suggests that not everyone is affected and most people adjust after just a few weeks of eating them.
In a recent study, data from three randomized controlled trials was analysed to determine if the levels of gas and discomfort people experienced when they ate legumes changed when they ate them regularly for a number of weeks.
Healthy adults were asked to eat half a cup legumes (pinto beans, black-eyed peas or navy beans) or carrots each day for 8-12 weeks. They were also asked to complete weekly questionnaires about perceived flatulence, bloating and stool frequency or consistency.
In the first week of each intervention the percentage of subjects reporting increased flatulence varied by bean type (baked beans 47%, pinto beans 50%, black-eyed peas 19%) and all were significantly higher than those eating carrots (3%). However in all three studies this percentage declined steadily with time so that by week 8 only 3% of participants still reported increased flatulence. Seventy percent or more of participants who experienced flatulence no longer felt it by the second or third week.
Reported stool changes were fewer than for flatulence, with only 10% reporting changes in the first week, which also declined with time. Reports of bloating also varied by bean type but declined over time to a level equivalent to controls (3%) by week 7. The highest reports of bloating were from pinto beans, followed by baked beans and then black-eyed peas.
For each of the symptoms, black-eyed peas (with a lower fibre content) resulted in generally lower responses than the pinto or baked beans. Age, BMI and macronutrient intake were not associated with symptoms, but more women than men reported increased bloating and stool changes. A small proportion of subjects reported increased flatulence even on control diets.
The authors conclude that people’s concerns about excessive flatulence from eating beans may be exaggerated, and varies by bean type across individuals. They state: “After a few weeks of daily bean consumption, people perceive that flatulence occurrence returns to normal levels”, although “a small percentage of individuals may be bothered by increased flatulence regardless of the length of time they consume legumes”.
The Australian dietary guidelines recommend eating legumes regularly and the research suggests there are many long-term health benefits to eating 2 – 3 serves per week. As with any high fibre food, it is best to eat small amounts at first and remember to drink water and get exercise to help reduce the chance of gas. For ideas on how to add more beans to your week, click here.
Winham DM, Hutchins AM.Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutrition Journal 2011;10:128.