All Beans Aren't the Same in Gassy Side Effects

Nov. 23, 2011 -- You might not know a line of Shakespeare, and you might even forget the words to "The Star-Spangled Banner," but this chestnut is a classic to all: "Beans, beans are good for the heart ... the more you eat, the more you ... "

You can finish the rest of the verse yourself, no doubt, but new research suggests that all beans are not created equal when it comes to your risk of flatulence. And even the worst offenders are not as bad as many might think.

Despite the known health benefits of beans and legumes, many people tend to shy away from them because of fears of excessive and embarrassing gas.

The new report analyzed flatulence and stomach distress, including stool changes and bloating, among people in three studies that looked at beans and heart disease risk.

The findings appear in Nutrition Journal.

The people in two of these studies ate either a half cup of pinto beans, black-eyed peas, or baked beans daily for eight weeks. People in the comparison groups of the studies ate canned carrots daily.

In the third study, participants ate either 1/2 cup of pinto beans or a serving of soup in the comparison group for 12 weeks.

Less than half of participants reported increased gas with pinto or baked beans during the first week, and 19% had increased flatulence with black-eyed peas during the first week. About 3% to 11% of participants reported increased flatulence throughout the study period, even if they were eating carrots, not beans.

"People can be made aware that increasing beans in the diet may result in more flatulence initially," writes study researcher Donna M. Winham, DrPH. She is an assistant professor of nutrition at Arizona State University in Phoenix. But "people's concerns about excessive flatulence from eating beans may be exaggerated."

Benefits of Beans

The 2010 U.S. dietary guidelines stress eating legumes several times per week, as they are rich in protein, fiber, vitamins, and minerals.  

In all three of these studies, there was a significant drop in total cholesterol and LDL "bad" cholesterol. High cholesterol is a significant risk factor for heart disease and stroke.

"Increasing bean consumption is a convenient and inexpensive way to enhance vegetable intake as well as boost [fullness]," the researchers write. "Stressing the health promotion aspects to consumers as well as imparting practical knowledge that perceived increase in flatulence are most likely temporary can go far in persuading consumers to add more beans to their diet."

The researchers suggest starting with smaller portions and experimenting with different types of beans to see if there are any differences in flatulence.

So just how do beans cause flatulence?

Beans are rich in fiber and resistant starches oroligosaccharides. These carbohydrates cannot be digested by enzymes found in the gut alone, so they are broken down by a process called bacterial fermentation in the intestines. The majority of flatulence is a result of this bacterial fermentation, the researchers write.

You can find out more on the benefits of beans, how to prepare them, and how to reduce their tendency to cause gas in this expert's blog on WebMD.