Above: Image © Badagnani, Wikimedia Commons

It's no mystery why everyone clears out after a chili-eating contest. Nobody (and I mean NOBODY) wants to be around after Big Ed has finished 20 bowls of chili. The reason: The beans in chili have a well-deserved reputation for causing gas. In fact, it's been scientifically proven... and I'm not just pulling your finger!

Did You Know? In 1968, scientists performed a study comparing the amount of gas one group produced eating a control diet versus the amount of gas produced by a separate group eating a diet of 51% of pork and beans. People on the control diet were blown away! Those on the pork and beans diet produced 161 MORE milliliters of gas per hour. What's so exceptional about beans then? Well, beans — "the magical fruit" — are one of many foods that contain oligosaccharides (oligo- meaning "few" and -saccharides "sugar"), or short chains of sugars. These short sugar chains come in different varieties and in lots of different foods.

For example, raffinose is an oligosaccharide found in such foods as cabbage, brussels sprouts, broccoli, asparagus, whole grains, and beans. Other oligosaccharides, such as lactose, fructose, and sorbitol can also lead to gas. You can find these sugars in foods such as milk and dairy products, onions, artichokes, fruits, and even sugar-free candies and gum.

So, it's the oligosaccharides that cause the gas? Well yes, through a couple of steps. The first step in digestion actually takes place in the mouth: Chewing breaks down the food, mixes it with the enzymes (proteins that speed chemical reactions) in saliva, and begins digestion.

Next, food is swallowed and travels down the esophagus (a muscular tube that connects to the stomach). At the stomach, acids break down foods even further. The food then travels to the small intestine (the uppermost region of the intestine), which absorbs nutrients through the gut wall.

However, humans don't have all of the necessary enzymes required to break down oligosaccharides into smaller sugars, leading to undigested sugars that the gut wall can't absorb.

Instead, the sugars pass to the large intestine (the lower region of the intestine that connects to the rectum). There, some of the 200 strains of bacteria that live in the human gut breakdown these sugars. As the bacteria act, they release some of the same gases found in the atmosphere. These gases are eventually discharged through the rectum as "gas".

Did You Know? Gas is mostly made of odorless gases: carbon dioxide, oxygen, nitrogen, hydrogen, and sometimes methane. The sulfur released during bacterial processing is what makes gas smell like a dumpster on a hot August day. Can gas be avoided? Two word answer: No way. Oligosaccharides are just one of several compounds that humans can't digest. More examples of gas-inducing foods include those that contain starch, such as potatoes and noodles, and fiber, such as fruits, grains, and vegetables.

Did You Know? Oligosaccharides, starches, and fiber are all carbohydrates (compounds made of oxygen, carbon, and hydrogen). However, not all carbohydrates cause gas. Granulated sugar, aka "the white stuff", is a carbohydrate that humans easily digest. If you've read this far into this long-winded response, you now know that incomplete digestion of foods other than beans also results in gas production. Gas is also generated through other chemical processes, like those involved in stomach digestion, or can enter into the gut through the blood. Even the air we breathe, when swallowed can result in gaseous release!

Did You Know? Most people produce anywhere between 1 to 3 pints of gas a day and pass gas about 14 times a day. So, is there no hope for a chili-off after party? Will Big Ed celebrate his victory alone? Fortunately, hope is on the horizon. Scientists have packaged the enzyme alpha-galactosidase (an enzyme from the mold Aspergillus niger that can help break down carbohydrates to digestible complexes) into pill form to be taken with meals.

For those milk-chugging contests, there are also products available that contain lactase (an enzyme that can help break down the sugar lactose found in dairy products).

With all this in mind, I say there's a good chance of a chili-off after party this year. Eat on, Big Ed. Eat on.

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Dr. CRAM would like to thank Alexandra Silveira for her expertise and help in answering this question. Alexandra is a graduate student studying cancer progression at the University of Alabama at Birmingham. Apart from her very cool profession as a science nerd she like music, art, dancing, and food (chili included).

Alexandra Silveira

I just received my PhD from the pathology department at the University of Alabama at Birmingham. I currently live in Providence, Rhode Island and co-manage the Entertainment section of CurioCity. In my spare time I read about science, watch horrible comedies, and am an aspiring Rock Band rock star.


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