Scientist Reveals 7 of the Strangest Things Coffee Does to Your Body

What do you get from coffee?

By Emma Beckett, Australian Catholic University

Some of coffee’s most unusual effects have little to do with caffeine. Its other bioactive compounds can interact with the gut, medications, and nutrients in ways researchers are still trying to understand.

Coffee is best known, and perhaps most valued, for its caffeine and its ability to make us feel more awake and alert.

But coffee is much more than caffeine dissolved in hot water.

Coffee is a chemically complicated plant extract containing hundreds of bioactive compounds. These can have all kinds of weird and wonderful effects in your body, even when you’re drinking decaf.

Here are seven of the strangest.

1. Coffee can make you poo

One study shows about three in ten people say they get the urge to poo shortly after drinking coffee.

This happens quickly, and with both regular and decaf. So it’s down to more than just the caffeine. But it’s not clear exactly which coffee compounds cause this.

Your colon can also be more active in the morning, and this is when most people drink their first coffee.

What you add to your coffee can also affect your bowels. The lactose in milk or some sugar-free sweeteners can also get the bowels moving, particularly if you consume a lot.

2. Coffee can affect your reflux, eyes and ears

Coffee can worsen reflux symptoms for some people. Reflux, when your stomach acid flows back up into your food pipe, isn’t always just felt as heartburn. It can contribute to coughing, wheezing, and other respiratory symptoms when reflux affects the throat and airways.

Caffeine can temporarily increase pressure inside the eye in some people with glaucoma or ocular hypertension, where pressure in the eye can already be high. Controlling this pressure is an important part of protecting the major nerve of the eye from damage. So some people with these conditions might be advised to limit their coffee and caffeine intake.

There’s also an ear condition where the tube connecting the middle ear to the back of the nose stays abnormally open, which can make you hear your own voice, or your breathing, unusually loudly. People with this condition, known as patulous Eustachian tube dysfunction, are sometimes advised to drink fewer caffeinated drinks and stay well hydrated, because dehydration can worsen symptoms. However, there is little direct evidence that coffee itself causes the condition.

Caffeine’s relationship with migraine is complicated: caffeine can help relieve a migraine, but too much, or suddenly having less than usual, can trigger one in some people.

How Climate Change Is Brewing a Coffee Crisis

The Rising Cost of Your Morning Brew

 Kate Petty

Severe weather, shifting trade policies, and a lack of support for small farmers are driving coffee prices sky high. Without urgent investment, your daily brew could become a luxury.

In January 2025, the price of coffee reached an “all-time high” for consumers in the United States; it is now poised to rise throughout the world. In May 2025, an article in Deutsche Welle stated that “the era of cheap coffee may be over.” This anticipated outcome is due to a combination of factors, including extreme weather, shrinking harvests, shifting trade policies, and rising production costs, which are straining the global supply chain. Meanwhile, the demand for coffee continues to rise.

Climate disruptions, such as prolonged droughts followed by excessive rain, are being seen in Vietnam and Brazil, the two largest coffee-producing countries. They are responsible for nearly 50 percent of the world’s coffee supply, and their losses have led to a decline in yields and an increase in prices. In November 2024, Coffee Intelligence reported that coffee prices had surged to a 47-year high.

At the same time, farmers have had to pay more for fertilizers, transportation, and labor. All these factors have contributed to the rising retail prices. “Many producers are grappling with increased production costs due to inflation and climate-related disruptions,” explained a March 2025 article in Coffee Intelligence.

The situation is likely to worsen owing to climate change. “Coffee plants will grow less productive as the earth’s temperature continues to rise, and practices like deforestation will continue to threaten the sustainability of the industry,” stated a January 2025 article in the New York Times.

Fluctuating Coffee Prices

Coffee is one of the world’s most widely traded commodities, second only to oil. Grown primarily in tropical regions, it is consumed across every continent. 

Historically, coffee prices have fluctuated, spiking during crop failures caused by extreme weather conditions or political instability in major coffee-producing countries, such as Brazil and Vietnam, and plummeting during periods of oversupply.