Do your coffee runs give you, well, the runs? This could be why.

Coffee is famous for giving your head a wake-up call in the morning. But for a lot of people, it also has a way of rousing the bowels.

So why, exactly, does our favourite caffeine hit leave us rushing to the toilet mid-morning?

Well, no one’s sure of the exact answer. Much of it comes down to the individual — some people are just more sensitive when it comes to their digestive system, while others may be experiencing the effects of underlying issues like Irritable Bowel Syndrome (IBS), which requires proper diagnosis and supervision for a doctor.

“It can be hard to determine exactly what it is that sets off an individual’s digestive system. Some people are simply more sensitive to some foods, and that includes coffee,” says Sydney-based GP Dr Greg Kelford.

For those of us without an underlying cause for coffee-related loo business, research has suggested the drink’s caffeine component may be to blame. Caffeine stimulates the digestive system and encourages muscle contractions in the digestive tract, resulting in — you guessed it — a little private time in the small room. (Post continues after gallery.)

Another theory is that when your morning coffee reaches your stomach, it serves as a catalyst to get your bowels going, which results in the urgent ‘number two’ situation. The body registers something coming in and gets ready for something to go out again.

Dr Kelford says this is precisely why people should make sure to eat a good breakfast at the beginning of the day. “Without food in your stomach, your digestive system is woken up purely by caffeine in coffee. It’s really not ideal due to the effects we already know caffeine has on the body,” he explains.

That’s all well and good, I hear you say, but I thought we were talking about caffeine related ‘runs’ here? Well, if you’re experiencing loose bowel movements after coffee, caffeine may still be to blame because it affects the body in several ways.

Firstly, caffeine can trigger a laxative effect in some people, but it can also increase the amount of bile production in the digestive system due to the acidic properties in coffee. This could result in a person experiencing loose bowel movements — the theory is that coffee prompts the body to expel waste before it's done completing the necessary processes associated with breaking down the contents of the stomach.

It's also thought the 'coffee runs' are prompted by neurons that surround the digestive tract. The digestive system is highly complicated — it's not only governed by physical stimulation (i.e. food entering your stomach), but is also influenced by chemicals in the body, which are found in substances like coffee. With these chemicals comes an electro-muscular response, which can put your system into overdrive and force your bowel movements to be looser than usual.

Fortunately, people suffering a less-than-ideal morning routine have a few ways to address the issue.

Number one: look at the kind of coffee you're drinking. According to Women's Health, richer blends like espresso typically contain less (yes, less) caffeine than other coffee choices, and are therefore gentler on the stomach and digestive system. You should also look at the quality of the coffee you're drinking regularly with cheaper blends of coffee having higher levels of caffeine than premium coffee blends. (Post continues after gallery.)

Next, you should consider the amount of coffee you're drinking. Obviously consuming high levels of caffeine will affect your system far more than if you were to restrict yourself to a cup or two.

"Drinking excessive amounts of coffee is damaging to several bodily functions which of course includes the digestive system" says Dr Kelford.

"While coffee itself does possess some health benefits, studies have shown that consuming large amounts can have a detrimental effect on the stomach lining, kidney function and can exacerbate or even cause issues such as heartburn and indigestion.

You can also reduce the effects of a morning coffee on your bowels by limiting the amount of additives, like sweetness and creamers, to your cuppa. Avoiding artificial sweeteners in favour of raw sugar may also have a positive effect.

How many coffees do you have per day? Do you experience any, um, side effects?