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Beans are a delicious and nutritious food full of microbiome boosting fiber and plant-based protein, and they are unfortunately notorious for causing digestive distress and excess gas. That does not necessarily mean we should stop eating them, however, as beans of all kinds have been a staple in the human diet for thousands of years. While they contain certain compounds that may make them difficult to digest, there are many simple cooking methods that can help to minimize the negative gastrointestinal symptoms and actually make beans even more nutritious.

“Raffinose is broken down by the enzyme alpha-galactosidase (α-GAL), however humans and other monogastric animals like pigs and chickens lack this enzyme.”

The reason beans cause abdominal bloating and gas is due to a specific type of sugar called an oligosaccharide, specifically raffinose, that the human body is unable to digest. Raffinose is broken down by the enzyme alpha-galactosidase (α-GAL), however humans and other monogastric animals like pigs and chickens lack this enzyme. Thus, it travels through our stomachs and small intestines undigested, and is finally broken down by the bacteria in our large intestine, where “the metabolism of raffinose by these microbes produces CO2 and H2 gasses, causing flatulence in the stomach.”

Beans also contain a large amount of soluble fiber, which retains water and forms an almost gel-like substance during digestion, effectively slowing the rate of digestion. This type of fiber is known to cause gas as it is more likely to be fermented by our gut microbes than insoluble fiber, which passes through our digestion untouched. Overall, fiber is a beneficial part of our diet, the breakdown of which produces short-chain fatty acids that benefit metabolism, inflammation, and disease regulation. Some people are more sensitive to large amounts of fiber than others, and you may find that you need to slowly increase your intake until your body becomes acclimated.

“…soaking dried beans in water for about 8-12 hours has been shown to reduce the contents of oligosaccharides”

If you are used to avoiding beans because of their negative digestive effects, there are a number of ways to mitigate these effects by improving their digestibility through preparation and cooking. For example, soaking dried beans in water for about 8-12 hours has been shown to reduce the contents of oligosaccharides including raffinose, thus lowering the levels of indigestible compounds. The soaking liquid should also be disposed of before cooking to remove the sugars lingering in the water.

In addition to simply soaking beans before cooking, it is suggested that adding kombu, a type of dried seaweed, can aid in digestion as well. Kombu contains the enzyme necessary to break down raffinose, alpha-galactosidase, therefore adding it during cooking, and even while soaking liquid, can aid in breaking down the gas causing compounds before you actually consume the beans. Plus, it contains beneficial vitamins and trace minerals, making the beans even more nutritious.

“By minimizing phytates in beans, our bodies are able to absorb and utilize a larger amount of the beneficial nutrients”

Soaking beans may also render them more nutritious as it reduces the phytate content, which are anti-nutrients that can decrease the absorption of iron, zinc, magnesium, and calcium. By minimizing phytates in beans, our bodies are able to absorb and utilize a larger amount of the beneficial nutrients when compared to beans that are not soaked prior to cooking. This was not, however, shown to make the protein content anymore bioavailable or digestible.

“Pressure cooking may also aid in the breakdown of gas-producing sugars and make beans more digestible in general prior to consumption.“

Aside from phytates, beans contain lectins, which are proteins that bind to carbohydrates as part of a plant’s natural defense mechanism. They can interfere with the absorption of calcium, iron, phosphorus, and zinc. Pressure cooking has also been found to reduce lectin levels as well as allow food to maintain more of its nutrients. Pressure cooking may also aid in the breakdown of gas-producing sugars and make beans more digestible in general prior to consumption.

As humans have been consuming beans for centuries, it is no question that they are a valuable part of our diet both nutritionally and culturally. By preparing and cooking them in a traditional manner, we can render them more digestible as well as reduce levels of anti-nutrients making them more nutritious. So the next time you have beans for dinner, make sure to purchase dried beans, soak them overnight, and then pressure cook them for optimal digestion.