This article is part of Insider's weekly newsletter on sustainability, written by science reporter Morgan McFall-Johnsen.
Legumes do something special that other plants can't do: Unlike most of their green counterparts, bean and lentil plants can absorb nitrogen right from the air.
Working with the bacteria on their roots, legumes pull nitrogen from the atmosphere and turn it into ammonia. That's a form of nitrogen that all plants can use. Legumes add that ammonia to the soil around them, allowing other plants to fuel their own growth.
"They are essentially nature's fertilizer factory," Liz Carlisle, an assistant professor at the University of California, Santa Barbara, and author of the book "Lentil Underground," told Insider.
That's why Iroquois and Cherokee people have long planted beans alongside corn and squash. It's also why farmers in Middle-Ages Europe sowed their fields with peas and beans for a season each year.
Today, legumes are more environmentally friendly than synthetic fertilizers, which require fossil fuels to produce, leach dangerous pollution into waterways, and release the powerful greenhouse gas nitrous oxide into the air.
Beans and lentils are also a protein-rich food with lower emissions than meat. For example, producing 100 grams of protein from beef emits nearly 90 times more carbon than the same amount of protein from peas, according to Our World in Data.
That means legumes could be a powerful tool in building a more-sustainable agricultural system. But Nina Ichikawa and other researchers at the Berkeley Food Institute suspect that something is holding Americans back from eating more beans.
Who's afraid of beans and lentils?
Ichikawa sees beans and lentils overlooked on cooking TV shows, on the covers of food magazines, and in the menus of new health-food restaurants. People have told her they don't like beans, don't know how to cook them, or don't want to deal with the gas they get from eating them. Ichikawa calls this "bean hesitancy" or, in more severe cases, "bean resistance."
Carlisle has seen it, too. In 2016, she co-authored an informative booklet about lentils with Montana State University. She said their surveys found Montana residents' biggest concern about lentils was flatulence. Today, she says her friends who grow beans and lentils find many potential customers are wary that it will take too long or be too difficult to cook them.
"We don't need to research what they do in the soil — there's mountains of research proving that. We don't need to research what they do for the human body — there's mountains of research proving that. We don't need to research how many ways there are to cook it, because there's mountains of cookbooks also proving that. But we do need to understand what is this hesitancy among Americans to eat beans," Ichikawa told Insider.
Ichikawa launched an effort to research American bean consumption in 2019. Working with the UC Berkeley Alternative Meats Lab, she and two student researchers began to survey people at festivals about their views on legumes. They also began assessments of bean varieties — their nutritional value, agro-economic merits and challenges, and culinary histories. The research lost funding at the beginning of the pandemic, though, and Ichikawa is still searching for new funds.
"It just really distresses me when people are thinking that they need to spend billions of dollars on researching a vegetarian protein that will be affordable," she said.
In September, it cost an average of $4.86 to buy a pound of ground beef in US cities, according to the Bureau of Labor Statistics, whereas one pound of dried beans cost about $1.68. At Walmart, 1.5 pounds of Impossible Burger — a plant-based patty famous for appearing to bleed like meat — costs $9.44.
"I just don't want us to waste time on trying to find an analog for all of the amazing things that beans already do," Ichikawa added.
