Giving up coffee has long been seen as something to boast about. Drinking a daily morning latte, with top-ups of filter, drip, or shots of espresso later in the day, is one of those habits people fret over. Am I drinking too much? Should I be drinking any at all? Can my body even function without it after decades of expecting a cup first thing?
But more evidence is emerging to show that coffee can have genuine long-term health benefits, if consumed in the right way and at the right volume – although unfortunately, choca-mocha lattes with whipped cream, almond syrup and sprinkles aren’t what we are talking about here.
The effect of caffeine on heart health is one of the key fears many of us have about drinking too much coffee. Links have long been made between caffeine and heart palpitations, with those sensitive to caffeine feeling that it makes their hearts beat faster or seem to be pounding.
The great news from a recent study in the New England Journal of Medicine (NEJM), published on 23 March, is that drinking coffee does not “result in significantly more daily premature atrial contractions [extra beats in your heart rhythm] than the avoidance of caffeine”.
The study was led by internationally respected heart rhythm expert, Dr Gregory Marcus. The randomised trial, which sought to understand “the acute health effects of coffee consumption [that] remain uncertain”, put pedometers, glucose monitors, and electrocardiogram patches on participants, and sent out daily text messages asking them to drink or avoid coffee.
Although these results are promising, the British Heart Foundation (BHF) still cautions against over-consumption.
“Drinking moderate amounts of caffeine – up to four or five cups of coffee a day – doesn’t seem to have a negative impact on the heart and should be fine for most people,” explains senior BHF dietitian Tracy Parker. “However, some are more sensitive to caffeine and can experience palpitations, so they should avoid it.”
The NEJM study did find a drawback to drinking coffee, which is that it affects sleep, with coffee-drinking participants losing 35 minutes sleep, on average, compared with the non-coffee drinkers. Another study, from the Journal of Clinical Sleep Medicine, looked at how the time of day when you drink your coffee affects sleep, and concluded that it’s best to stop any caffeine intake at least six hours before bedtime.
A lack of sleep has health implications of its own. Losing an hour of sleep a night is correlated with a number of serious health outcomes, including cardiovascular disease, cancer and cognition problems. However, researchers who conducted the NJEM study say the effects of losing half an hour, as found in this study, are “less certain”.
The amount of caffeine in each drink varies. Each 200ml cup of filter coffee contains 70mg-140mg of caffeine, with around 63mg in a single shot of espresso. Drink as much as 500-600mg over a period of a few hours, warns the American Academy of Sleep Medicine Foundation, and it could have the same effects as taking stimulant drug like amphetamines.
There are clear advantages to the wake-up call we get from a hit of caffeine. The British Dietetic Association (BDA) lists alertness, increased attention, and “increased performance in short-term high-intensity and endurance exercise” as health benefits to drinking caffeine.
All of these claims are endorsed by the EU’s European Food Safety Agency, and point to what most of us know without the need for science or studies – we feel more awake after a morning cuppa.
Mental health and dementia
Kimberly Wilson, psychologist and author of Unprocessed: How the Food We Eat Is Fuelling Our Mental Health Crisis, which came out last month, has good news for coffee fans. “As well as increasing alertness and attention, caffeine is associated with elevated mood and even mild euphoria in some people,” she tells i.
“There is even evidence that caffeine can help to alleviate depression and reduce thoughts of suicide. Regular caffeine consumption is also associated with a reduced risk of cognitive decline, dementia and Parkinson’s, due to the effects of both the caffeine and polyphenol content of coffee.” Polyphenols are plant compounds known to have a protective role against cancer, heart disease and inflammation.
“But there is a limit. After around 400mg of caffeine per day (four to five cups of coffee), there is an increased risk of negative effects. At high doses, or in people who are genetically sensitive to caffeine, it can cause feelings of anxiety or jitteriness. Drinking coffee later in the day can also perturb sleep, which has negative consequences on mood regulation, attention, and in the long term, overall brain health.”
Coffee gets our bodies moving, too. Those on the NEJM study took 1,000 more steps than uncaffeinated participants when directed to have a coffee-drinking day. 1,000 steps could mean 10 minutes of movement, which is enough, according to another recent study, to help prevent early death.
According to the Zoe Health study, a vast ongoing investigation into gut health led in the UK by Professor Tim Spector, coffee is great for our gut. You might rely on a morning cup to get your bowels moving, and that’s because the caffeine stimulates both stomach acid and digestive contractions, which move food through your gut and help keep you regular.
Coffee is also flush with anti-inflammatory molecules that maintain gut health, and improves the diversity of our gut microbiome, which leads to better health overall. “We saw a very strong correlation between drinking coffee and the composition of the gut microbiome,” Dr Nicola Segata, professor of computational metagenomics at the University of Trento in Italy, told the Zoe study. “We noticed that people who drank coffee tended to have higher microbiome diversity.”
The findings were dose-dependent, with those drinking more than four cups per day showing the highest microbiome diversity, which is linked to a lower risk of obesity and other chronic diseases.
Caffeine alone is not a cause of weight gain, but it’s important to manage how we take it. The calories in a typical latte range from less than 100 with skimmed milk to almost 200 with full-fat milk.
“Whether drinks are caffeinated or not, it’s important to think about their sugar and saturated fat content, points out senior BHF dietitian Tracy Parker. “Sugar, syrups, honey, whole milk and cream add calories and saturated fat, which can cause weight gain and raise cholesterol levels, increasing your risk of heart disease.”
Apart from the sleep issues, there’s a growing body of evidence that suggests coffee is more likely to be a healthy habit than a harmful one. “For most people, moderate coffee consumption can be incorporated into a healthy diet,” according to Frank Hu, chair of the Department of Nutrition at Harvard’s School of Public Health.
He says that between two and five cups a day is considered moderate, and linked to reduced type 2 diabetes, heart disease, liver and endometrial cancers, Parkinson’s, depression and even early death.
When might we consider switching to decaf? Many find they develop headaches or feel jittery and anxious following too much caffeine. Decaffeinated coffee is made by extracting the caffeine from the raw bean, which means that a cup of decaf retains the other health benefits of coffee, but will taste different and is harder to keep fresh.
If you struggle with headaches, anxiety and high blood pressure, it can be a good idea to avoid caffeine. Decaffeinating coffee will never remove 100 per cent of the caffeine, but decaf has 97 percent less caffeine, or 7mg per cup compared with 70-140mg for a regular cup of coffee.
Where did coffee get its bad rep?
There are several theories as to why early studies found coffee to be bad for our health, which over time led to its controversial reputation, and a lack of clarity among coffee lovers over how much they should drink. Harvard’s Frank Hu has pointed out that in the early studies linking coffee with heart disease and asthma, many of the participants smoked. We now know that these health issues are linked to smoking.
Around the world, coffee is made and drunk in many different ways. The BDA posits that early research was carried out by boiling ground coffee, the traditional Swedish method, which was associated with heart disease. However, in places where the coffee isn’t boiled and is filtered, the heart disease link disappears.
There’s also the human instinct to fear that anything we enjoy comes with a catch.
“In the past, I think a lot of people thought, ‘Oh, coffee’s so delicious, there must be something bad about coffee,’” Hu told Discover Magazine. “So I think the good news is that [for] most people, coffee actually confers some health benefits.”