UPDATED: August 16, 2025
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I've been asked a number of times to state my article's bottom line, up front (known by the military acronym, BLUF). So, today's BLUF is: Beans are good for us because they contain lots of undigestible fiber and resistant starches, nourishing our health-promoting gut microbiome. Let us all eat more beans, and collectively push for more tolerant social norms about gas.
Know Your Beans
Beans are nutritional powerhouses, packed with protein, soluble and insoluble fiber, resistant starch, vitamins, minerals, and polyphenols, all of which have significant health benefits. Dietary fiber, absent in animal-based food sources, encompasses a broad category of complex carbohydrates found in whole grains, legumes (beans, pulses, peas), and vegetables such as broccoli, cabbage, asparagus, and cauliflower. Fiber and resistant starch arrive in the large intestine undigested, and nourishes trillions of organisms in a complex ecosystem known as the gut microbiome.
Resistant starch is a specific type of complex carbohydrate that also escapes digestion and contributes to gut health when it is fermented in the large intestine. Insoluble fiber primarily acts as bulking agent, while soluble fiber and resistant starch act as food sources for our beneficial gut bacteria.
Recent research reveals that dietary legumes can significantly enhance the diversity of our gut microbiome, the complex ecosystem of organisms playing a crucial role in our overall health. The daily consumption of beans promotes the growth of beneficial bacteria, which improves gut health, and also affect immune system functioning and the regulation of inflammatory responses.
The high fiber and resistant starch content of beans act as prebiotics, encouraging the growth of beneficial bacteria in our intestines. The amino acids and other nutrients in beans help our colonic bacteria flourish. Dried and canned beans are widely available and relatively inexpensive. With a little imagination it is easy to include some beans with every meal. They are very versatile, and can be used in stews, soups, chili, etc. The same beans can be seasoned differently to create Mediterranean, Indian, or Mexican dishes.
I add black beans to my breakfast oatmeal, eat carrots dipped in hummus with my lunch, and put garbanzo beans on my dinner salad. I make a bean salad with green beans, pinto and kidney beans, and spread refried beans on whole wheat toast with cheese. If we are kind to our gut microbiome and feed them beans, our resident microbes will do all sorts of nice things for us, including help with our mental health via the gut-brain axis.
Something to keep in mind is that beans don’t contain “complete” proteins because they lack some essential amino acids. The same is true for whole grains. However, beans and grains are the perfect complement for each other. Beans are low in methionine but high in lysine, while whole grains can be low in lysine but high in methionine. Like a good marriage, they are able to make up for each other’s deficiencies.
Passing Gas
The downside of a high-fiber diet is that its fermentation by intestinal bacteria is what gives some people daunting problems with gas. When we eat more beans, our generally silent intestinal passengers can suddenly become quite noisy.
Warning! Medical humor ahead:
Q: What do you call someone who shamelessly passes gas in the presence of others?
A: An anesthesiologist.
Gastrointestinal gassiness has three manifestations; eructations (burping), borborygmi (grumblings), and flatulence (farting). Eructations primarily involve the release of swallowed air from the stomach, ingested during eating, drinking carbonated beverages, or unconsciously swallowing air due to anxiety. Rumbling sounds occur when gas and liquid move through the intestines, and amplified when the stomach is relatively empty. The sounds result from peristaltic contractions. Flatulence occurs when there is a release of the gaseous end products of microbial metabolism.
The gassy downside can occur when we first add more beans to our diet. Intestinal gas, commonly known as flatus, is primarily composed of nitrogen, oxygen, carbon dioxide, hydrogen, and methane. While more than 99 percent of farts are odorless, trace amounts can have sulfur-containing compounds such as hydrogen sulfide, which contribute to a foul odor.
Foods high in the sulfur-containing amino acids, methionine and cysteine, are cruciferous vegetables, eggs, and certain meats. The intestinal production of hydrogen sulfide and other sulfurous gases can contribute to the noxious odors of flatulence. Methane, the main flammable component of flatus, is produced by specific colonic bacteria.
Hopefully, we weren't too traumatized as children by the methods our parents used to teach us not to fart in public. There's a pair of mixed-messaging poems that I recall from my youth:
‘Tis better to fart and stand the shame, than not to fart and stand the pain.
Beans, beans, the musical fruit; the more you eat, the more you'll toot.
The more you toot, the better you'll feel, so eat some beans with every meal.
Just to be clear, beans are not a fruit. Fruits are plant structures that contain seeds. Beans, on the other hand, are seeds that develop within a pod-like structure characteristic of plants in the legume family. While beans are often considered vegetables for culinary purposes, they are scientifically classified as seeds.
There is an abundance of folksy proverbs about flatulence found throughout recorded history and across many cultures, all expressing similar sentiments. Perhaps this reveals a basic human tendency to find humor in naturally occurring violations of social taboos. For example:
Wherever ye be, let your wind go free.
In church and chapel, let it rattle!
Although it's generally more comfortable to release built-up gas whenever possible, holding it in won't pose much of a risk for developing diverticular disease. Much more important preventive measures are maintaining adequate fiber intake, staying well hydrated, and avoiding chronic constipation. When you think about it, it’s pretty impressive that the anal sphincter is able to hold back solids while releasing gases, at least for those individuals who don't need to see a proctologist.
Warning! Medical humor ahead:
A psychiatrist and a proctologist decided to share an office building. In order to boost public attention, they hung out a sign that said, Odds and Ends.
Beans are especially rich in a type of short-chain carbohydrate called raffinose, a major contributor to flatulence. This complex sugar molecule (an oligosaccharide) can initially produce gas when we don't have enough of the necessary intestinal bacteria to break it down efficiently. However, with regular bean consumption, our gut microbiome will adapt, and the population of bacteria that can digest raffinose will increase, resulting in less farting.
Soluble fiber and resistant starch also contribute to bacterial gas production in the large intestine. Pectins from fruits, beta-glucans from oats and barley, and various gums and mucilages are all readily fermented. So are sugar alcohols (polyols) used as natural sweeteners. Research suggests that gas production is actually a positive sign, indicative of healthy activity by our gut microbiome.
An aside: Age does come with certain privileges, such as grandpa telling a grandchild to pull their finger, and then loudly farting when they do. That’s guaranteed to produce a laugh, much to the consternation of the child's parents if they are fart-phobic. As you might have guessed by now, there’s no fart-shaming allowed in my household.
A 2023 dietary intervention study, funded by the American Cancer Society, suggests that beans as prebiotics have a potential therapeutic role for enhancing the gut microbiome to regulate metabolic markers associated with endogenous obesity and colorectal cancer.
If an enzymatic dietary supplement such as Beano® actually decreased gas production, it would do so by breaking down the complex carbohydrates into simpler sugars. This would deprive the gut microbiome of what it needs to thrive, and as you will see, keeping your gut microbiome well nourished can be a win-win situation.
Gut Farming
Consider including beans in all your meals as a way of “farming” your gut microbiome. Encouraging the growth of beneficial bacteria can result in better digestion and improve overall health. However, individual experiences are unpredictable, and as they say, your mileage may vary (YMMV). The best strategy is to increase your bean consumption gradually, and allow enough time for your microbial flora to adjust to the changes in your diet.
Several studies that looked into the relationship between beans and gas found that people's bodies gradually adjusted over time. Within three to four weeks of adding beans to their diet, participants had returned to their normal levels of gas production. There is also some evidence that soaking dried beans for at least 12 hours before rinsing and cooking in fresh water can reduce their level of raffinose. See this link for cooking tips.
As you increase your fiber intake, it becomes even more important to stay adequately hydrated. Fiber absorbs a lot of water as it passes through the digestive system. When you don’t drink enough water with a high-fiber diet, you risk becoming constipated.
It takes about eight weeks for the daily consumption of one cup of beans to improve gut microbiome diversity and composition. Begin by adding only a half-cup per day for the first two weeks, and divide the quantity among your meals, to help your microbiome acclimate.
Maintaining the health benefits of beans requires consistent consumption. Returning to a low-fiber diet will result in the reversal in positive changes over the next eight weeks. Once you’re used to eating beans, don’t quit. There is persuasive evidence for the role of beans in reducing the risks of obesity, cardiovascular disease, and colorectal cancer.
Beans and the Brain
There are more neural connections between our gut and our brain than there are between our brain and our spinal cord. This is known as the “gut-brain axis,” which refers to the bidirectional communication pathway between the gastrointestinal tract and the central nervous system. This complex network involves neural, endocrine, immune, and microbial pathways, influencing both gut function and brain activity.
The dietary fiber and phytonutrients found in beans not only have anti-inflammatory and anti-oxidant properties when fermented by bacteria in our gut, they are also converted into chemical compounds that help to elevate our mood and improve cognitive function. Most of our body's serotonin comes from our gut.
Short-chain fatty acids (SCFAs) produced by gut bacteria protect intestinal cells and regulate metabolism. They also play a crucial role in gut-brain communication, acting as messengers that influence brain function and behavior. These molecules, derived from the fermentation of dietary fiber, can affect the brain through various pathways, including direct effects on the nervous system, modulation of the immune system, and influencing hormone production.
SCFAs can directly stimulate vagal afferent nerves, which connect the gut and brain, transmitting signals related to appetite, inflammation, and other processes. They can also influence neurotransmitter levels and neurotrophic factors, potentially impacting neuroplasticity. SCFAs can cross the blood-brain barrier, affecting glial cell activity and modulating neuroinflammation.
SCFAs can bind to receptors on enteroendocrine cells, triggering the release of hormones such as glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), which regulate appetite and insulin sensitivity. They can also influence the immune system by affecting the production of cytokines and modulating the activity of immune cells in the gut and brain. Changes in gut microbiota composition, and consequently SCFA production, have been linked to various health conditions, including obesity, irritable bowel syndrome, and neurodegenerative diseases.
Cultural Influences
Widely accessible and cost-effective commodities, beans are very popular with populations south of the U.S. border. Gallo pinto, which translates as “spotted rooster,” is a popular Central American rice and bean dish that has attained “national dish” status in Costa Rica and Nicaragua. The name reflects the appearance of black beans speckling white rice. A healthier modification would be to use whole-grain brown or red rice instead of white. Add some veggies, and you have a complete meal.
Unfortunately, because of their association with farting, beans are all too often avoided by up-tight White Americans. That’s why I'm calling for a cultural shift, where a fart is considered no worse of a social infraction than a sneeze, and is similarly worthy of an exclaimed Gesundheit! (“Wishing you good health!”). So, let's hear from the bean-eaters, loud and proud. 🤣
More About Healthy Eating
For an in-depth look at the nutritional principles behind a healthy diet, how to make healthy meal preparation easier, and 100 recipes to inspire your culinary creativity, check out my eBook, “Rx for Healthy Eating.” It is available from Barnes & Noble, Google Play Books, and the Amazon Kindle Store. The book costs less than a burger and fries, and comes with free updates. Unlike fast food, it could actually prevent a heart attack.
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