That cup of coffee in the morning not only wakes you up for the day, it also gives a boost to billions of friendly microbes living in your digestive system. Because according to a growing body of research, there’s evidence that your espresso can positively impact your microbiome (gut bacteria), leading to better overall health and even longer life.
“The microbiome includes legions of species of ‘good bacteria’ that work collectively and individually to improve our health,” says Nicola Shubrook, a registered nutritionist and functional medicine practitioner.
“These microbes are increasingly seen to be beneficial to our metabolic health, weight management and mental health,” she continues. “Coffee contains several compounds that act as prebiotics, meaning they feed the probiotic beneficial bacteria by providing them with nutrients needed for growth and function.”
The impact of coffee on our intestinal flora appears to be twofold. First, caffeine itself acts as a stimulant, increasing the number of beneficial bacteria in the intestines. “The greater the diversity in your digestive system, the better,” says Shubrook.
A 2023 study published in the journal Nutrients examined the association between caffeine, coffee consumption and the gut microbiome. The results showed that microbiome richness was higher in regular coffee drinkers, who had a greater number of helpful people Alistipes And Faecalibacterium species (believed to have preventive effects against liver fibrosis and cardiovascular disease) and lower levels of harmful substances Erysipelatoclostridium, which causes intestinal problems. This follows an earlier study that found coffee consumption was associated with an increase in bifidobacterium, microbes thought to aid in the digestion of fiber and prevent infections.
Coffee also contains plant compounds called polyphenols, a category of compounds that occur naturally in plant foods such as fruits, vegetables, herbs, spices, tea, dark chocolate and wine. “Polyphenols act as an anti-inflammatory antioxidant,” notes Shubrook. “They can help reduce the risk of cancer by neutralizing harmful free radicals, the chemicals that damage cells.”
The specific polyphenol in coffee is known as chlorogenic acid. According to a 2020 study published in Experimental and clinical sciencespatients who consumed coffee rich in chlorogenic acid lowered their risk of type 2 diabetes and non-alcoholic fatty liver disease – they also lost weight. Scientists concluded that this was likely related to an increase in the number of bifidobacteria in the intestines (one of the “good” ones).
Established studies have also shown that caffeine is good for your gut, stimulating the colon and leading to regular bowel movements. A 1990 study found that people who drank coffee tended to go to the bathroom 30 minutes after drinking a cup.
In so many ways, it seems like the gut loves a cup of joe. But is there a best way to prepare and serve your coffee?
Black or with milk?
Experts tend to unanimously agree that black coffee is better for you than a cappuccino, latte or flat white. “It has been shown that milk hinders the absorption of polyphenols,” says Julia Kopczyżska, a microbiologist at the Polish Institute of Biochemistry and Biophysics in Warsaw. “Adding tons of cream or sugar turns your coffee into a dessert. Sugars will do more damage to your blood sugar than coffee can do.”
Which mix should I choose?
There are two main types of coffee beans: Arabica and Robusta. “Each has different qualities at certain roasting stages,” says Kopczyńska. “Although lighter roasts generally have higher caffeine content, they retain more antioxidants than darker roasts. Lightly roasted Robusta beans contain more antioxidants than the blonde roasts of Arabica coffee.”
Most coffee shops in the UK chain use medium roast Arabica beans, although Costa does sell a blend of Arabica and Robusta. Black Sheep Coffee also sells Robusta.
“My favorite is Exhale Coffee, a dark Arabica grown with the highest levels of antioxidants,” says Shubrook. “It’s the perfect black coffee, with no tampering at all.”
The length of time the beans have been stored also affects polyphenol content, with a decrease seen in the number of coffee beans stored for twelve months or more.
What about instant coffee?
Although research shows that instant coffee may contain even more polyphenols and minerals than ground coffee, coffee also contains 100 percent more of the chemical acrylamide; coffee substitutes can contain even 300 percent more. “Acrylamide forms in coffee during the roasting process and if people are exposed to it in higher amounts, it can increase the risk of nerve damage and cancer,” says Kopczyńska.
However, there is no reason to worry. “Coffee consumption, both instant and ground coffee, is not associated with the development of cancer,” Kopczyńska continues. “However, the
The European Food Safety Authority (EFSA) recommends reducing the amount of acrylamide in our diet. That is why we also recommend classic ground coffee over instant and coffee substitutes.”
How many cups should I drink per day?
A recent survey of centenarians living in the European ‘longevity’ Blue Zones of Sardinia and Ikaria in Greece found that almost all drank two to three cups of black coffee a day. “Assuming a cup of coffee weighs 220 ml, two to three cups is the sweet spot, with five being the upper limit,” says Kopczyńska.
Before you grind your beans or stamp your loyalty card, it’s worth considering the caffeine content of your drink. “Although coffee is beneficial, not everyone can metabolize it as efficiently,” notes Shubrook. Kopczyńska agrees. “The maximum recommended amount of caffeine is 400 mg per day. Anything above 600 mg has been linked to insomnia and high blood pressure.”
According to Kopczyńska, a home-brewed cup of coffee contains between 70 mg and 140 mg of caffeine, depending on the bean and the brewing method. Meanwhile, the average coffee in the major shopping streets contains 180 mg caffeine. Pret espressos and cappuccinos contain this amount. Others may be higher: A medium Costa cappuccino contains 325 mg – almost your entire recommended daily intake in one cup.
You might be surprised to hear that most espressos contain less caffeine than other types of coffee: a 30ml/1oz Caffe Nero espresso contains 45mg of caffeine, and a Starbucks only 33mg. Gregg’s espresso clocks in at 75 mg. (But a cup of espresso also contains a much smaller amount of liquid than a latte or a cappuccino.)
How should I prepare my coffee?
The way you prepare your beans preserves different compounds, those that are beneficial and those that are not so good for you. Brewed coffee contains cafestol and kahweol, chemicals known as diterpenes. “Cafestol and kahweol are known for their anti-inflammatory, anti-diabetic, anti-cancer and polyphenol-containing properties,” says Kopczyńska. “These are 30 times higher in unfiltered coffee.”
On the other hand, she says, unfiltered coffee contains oils that have been shown to increase cholesterol levels. “Filtered coffee not only contains fewer coffee oils, but also contains less caffeine compared to unfiltered coffee brewing methods.”
If you can get around the awkwardness of using an Aeropress, according to a 2023 study published in the journal Foods showed that this method is the best for preserving polyphenols. “In our study, the lowest total polyphenol content was found in the French press coffee (133.90 g gallic acid/liter) and the highest in the Aeropress brew (191.29 g gallic acid/liter),” the authors wrote. “The highest antioxidant potential and polyphenol content was observed in the brew made in the Aeropress.”
Can I make my coffee healthier?
Adding natural spices – as opposed to sugars or syrups – can provide additional health benefits. “Cardamom has an anti-inflammatory effect and regulates blood sugar levels,” advises Kopczyńska. “Ginger, a natural painkiller, improves digestion and lowers cholesterol. If you use milk, turmeric added to a latte is known for its beneficial effects on metabolism and the immune system.