Why Coffee Makes You Use the Restroom

Why Coffee Makes You Want to Use the Restroom

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Understanding One of Coffee’s Surprising Effects

If after your morning cup of coffee you find yourself with an overwhelming urge to run to the restroom, know that you are not alone! This is a topic rarely discussed in polite company, yet many are well-acquainted with this phenomenon. It turns out that coffee not only awakens our minds but also stimulates our digestive system to become more active.

The activity of the colon increases within four minutes of starting to drink your morning coffee

This is arguably one of the most well-known effects of coffee on the digestive system. A quick search online reveals numerous memes on the subject, and just as many myths exist around it. Let us delve into the facts.

According to one of the most recent studies, published in January 2022, coffee affects the peristalsis of the colon in 29% of the participants. This reaction is within the normal range and is not considered pathological. The manifestation of this effect varies among individuals.

How does this work?

The activity of the colon increases within four minutes of starting to drink your morning coffee. For decaffeinated coffee, this time extends to about 30 minutes. The increased peristalsis leads to significantly greater pressure on the intestinal wall muscles, causing wave-like contractions, which result in a strong urge to defecate.

Furthermore, coffee stimulates the secretion of gastric juice

It was initially believed that these effects were mediated by caffeine; however, decaffeinated coffee induces a similar response. Research shows that caffeinated coffee enhances activity deep within the intestines 60% more than warm water and 23% more than decaf.

It has been proven that the acids in coffee elevate the levels of the hormone gastrin, which stimulates involuntary muscle contractions in the stomach and drives intestinal activity. Some studies suggest that coffee also increases the production of cholecystokinin, another hormone that plays a key role in the digestive process.

Furthermore, coffee stimulates the secretion of gastric juice. This effect is known as the gastrocolic reflex—an innate response of the colon to the entry of food into the stomach. When we eat or drink, including consuming coffee, the stomach stretches, signaling the colon to contract and move the food mass through the digestive tract. This reflex may be more pronounced after drinking coffee, particularly in individuals sensitive to the beverage's effects.

Can Adding Milk to Coffee Enhance Its Laxative Effect?

Adding milk or cream to coffee not only diversifies the flavor experience but may also provoke increased intestinal activity.

Adding milk or cream to coffee not only diversifies the flavor experience but may also provoke increased intestinal activity

The reason lies in lactose—a disaccharide found in milk and cream. In the body, lactose is broken down into glucose and galactose. Without the enzyme required to break down lactose, lactose intolerance can occur. This intolerance may lead to diarrhea and other gastrointestinal issues within 30 minutes of consuming the beverage. Statistically, 65% of people experience difficulty digesting lactose, which can trigger the urge to use the restroom.

Use Morning Coffee to Care for Your Gut

If digestive waste remains in the colon for too long, it can lead to bloating, gas, cramps, and overall discomfort. The gastrointestinal tract is most sensitive and prone to irritation early in the day. A cup of warm, soothing coffee positively influences the gastrocolic reflex and promotes regular bowel movements.

Morning coffee is a simple and effective way to maintain gut health and overall well-being on a consistent basis.

The Mariko Aoki Phenomenon

Interestingly, the urge to use the restroom is not only triggered by drinking coffee directly but also by being in a coffee shop, bookstore, or shopping mall.

Dr. Saurabh Sethi, a California-based gastroenterologist and Harvard graduate, explained why a trip to a store or coffee shop might provoke the need to rush to the restroom: "This phenomenon is known as the Mariko Aoki effect, first described in Japan in 1985."

The Mariko Aoki Phenomenon

The term is named after a woman who wrote a note to a Japanese magazine sharing her experiences. Every time she wandered through a bookstore, she felt a sudden urge to use the restroom.

This phenomenon is also observed in coffee shops. Scientists are not entirely sure what triggers these urges, but there are several theories, most of which are based on specific aromas. It is believed that the scent of coffee, as well as ink and paper, has a laxative effect on people. Specifically, it has been proven that caffeine stimulates colon contractions even without ingesting it.

Another theory suggests that leaning forward and adopting a hunched posture—such as when browsing a bookshelf—"massages the digestive organs and facilitates bowel movements."

What to know

We are all unique; some people are more sensitive to medications, certain foods, and even water. Coffee is no exception—sensitivity to caffeine and its other components varies among individuals.

The urge to have a bowel movement after a cup of coffee can vary or even be absent altogether, depending on overall health, diet, and many other factors. For example, in cases of digestive disorders or irritable bowel syndrome, the laxative effect of coffee may be more pronounced.

We all wish to know more about this topic: which coffee most often causes a laxative effect, under what circumstances the effect is intensified, or does not occur at all. While scientists continue their research, we should pay close attention to our bodies, observe them, and note what works best for each of us. In any uncertain situation, it is best to consult a doctor for advice.

FAQ: How coffee affects digestive health and common reactions to this popular beverage

Coffee stimulates the muscles in your digestive system, particularly the colon, which can increase the urge to have a bowel movement.
Yes, decaffeinated coffee can still stimulate bowel movements, though the effect is typically less pronounced than with caffeinated coffee
Adding milk or cream to your coffee can enhance this effect, especially if you are lactose intolerant, as lactose can cause digestive issues
Yes, this is a common response and not typically a cause for concern. It is a natural reaction of the digestive system
This may be due to the Mariko Aoki phenomenon, where certain environments, like coffee shops or bookstores, trigger the urge to use the restroom, possibly due to specific aromas.
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