Beans, beans the magical fruit…
That schoolyard chant has a ring of truth to it.
The scientists call it “the perceived negative consequences of fitting pulses into the diet.”
True, lots of beans or any other pulse eaten in one go will very likely have unpleasant after-effects, researchers say. But eaten in moderation, pulses don’t cause nearly the intestinal hardship people assume.
“In looking at the results, we do conclude and interpret that our data do allay those concerns, that eating beans will cause gas,” said Alison Duncan, an associate professor in the department of human health and nutritional sciences at University of Guelph. She reported on a study that investigated the pulse effect on gastrointestinal bacterial populations, while at the same time trying to determine how well people could tolerate pulses eaten on a daily basis.
“A major reason for low pulse consumption is perceived negative side-effects,” said Duncan.
For their study, 21 healthy men each ate a half a cup a day of pulses (chickpea, pea and lentil) for four 28-day treatment periods, with 28-day breaks in between. The pulses were provided to participants as a spray-dried powder formulated into soup products.
A control group consumed potato soup instead.
Study participants all filled out questionnaires documenting cramping, bloating or flatulence.
Their results: high flatulence among all subjects all the time. That included those eating the potato soup. “Our data…. led us to interpret that we all have high flatulence all the time,” said Duncan. “We didn’t see that the pulses caused any more (flatulence) than our control group.”
Wendy Dahl, an assistant professor in the food science and human nutrition department at University of Florida was part of a study done in collaboration with University of Saskatchewan to investigate the prebiotic effects of chickpeas, that is, whether eating this type of pulse increases beneficial bacteria. Their study subjects also reported flatulence, but they did not find significant difference between those consuming the chickpeas and those who weren’t, Dahl said.
“For the most part, I think pulses have been given a bad name in terms of gastrointestinal symptoms,” she said. “There’s so many foods that we consume on a daily basis that also contribute to gas discomfort, but are never discussed.”
Likewise, a team of researchers at University of Manitoba also found only “mild to moderate” side-effects in their subjects, based on self-reporting during an eight-week study.
The findings are important for a food high in health benefits yet not widely consumed for various reasons, including this fear of getting gas.
It’s a prejudice based more to the way that we tend to consume pulses, that is, just occasionally and then in a relatively large amount, according to Duncan.
No one is suggesting anyone go out and eat a pile of beans, she stressed. “You should start up slowly in order to make it a part of your diet on a regular basis,” she said. “Introducing pulses into your diet at a moderate level, following the dietary guideline of a half-cup a day is not, from our data showing that it will have any gastrointestinal effects.”
That’s also what dietitians recommend.
“What I suggest to people, because pulses are very nutrient dense and fibre dense, is to do an adaptation period,” said Jane Dummer, a Kitchener-based registered dietitian who attended the symposium.
Dummer recommends starting off with about a quarter-cup a day, plus drinking lots of water and eating fruits and vegetables high in water content and then gradually increasing that amount to a half a cup per day three times a week. After a time, increase that amount to about three-quarters of a cup per day four times a week. “Our bodies can adapt to this high-fibre food,” she said.