In the UK alone, 34-41 million people are regular coffee drinkers, consuming approximately 98 million cups every day. Coffee has now overtaken tea as the country's most popular drink after water. Tens of thousands of studies have been conducted into its pros and cons, shifting coffee's status over the past couple of decades from a caffeine source to a superfood.
What Research Says About Coffee's Health Benefits
Research undertaken this year alone suggests coffee might protect against liver cancer, slow ageing, reduce the risk of dementia and improve heart health. Experts agree these health benefits come down to coffee's polyphenols, which Dr Rupy Aujla, GP, best-selling author and founder of the Doctor's Kitchen, describes as "plant compounds with powerful antioxidant and anti-inflammatory effects". Also found in berries, dark chocolate, nuts, seeds, herbs and spices, "they feed your gut bacteria, encouraging beneficial species, support gut lining integrity, help protect blood vessels, improve endothelial function and support healthy blood pressure," adds Aujla.
Dr Aaron Davis, senior research leader and coffee specialist at the Royal Botanic Gardens, Kew, agrees. He says: "Chlorogenic acids [a specific type of polyphenol] are believed to be the main source of antioxidants in coffee," present in their highest concentrations in green, unroasted beans. "Some polyphenols, like the chlorogenic acids abundant in coffee, slow glucose absorption and improve insulin sensitivity," says Aujla, adding that "regular polyphenol intake is also associated with lower risk of cardiovascular disease, type 2 diabetes and certain cancers".
How Roasting and Brewing Affect Polyphenols
This is the premise on which "healthy coffee" brand Exhale is founded. The B Corp-certified roastery produces organic, single-origin beans naturally high in chlorogenic acids, and free from mycotoxins, pesticides, moulds, yeasts and heavy metals. Co-founder and CEO Alex Higham had his lightbulb moment when he read a BMJ Umbrella Review in 2017 which found drinking three to four cups of coffee per day is associated with a 17 per cent lower risk of "all cause mortality". Higham points out these findings applied to "all coffee", but it kick-started a mission to create beans which would maximise the benefits.
When selecting coffee, Davis suggests "organic sources (irrespective of certification) that have been grown without chemical inputs will carry fewer health risks". Aujla says that "two to three cups a day appears to be the sweet spot in most cohort studies" to see the benefits, while balancing negative side effects — anxiety and poor sleep. He also suggests avoiding it during the first 60-90 minutes after waking when cortisol levels are naturally high, and stopping eight to 10 hours before bed to protect sleep. Filtered brewing (drip, V60, AeroPress) edges French press and espresso, which "retain more of the cholesterol-raising compounds".
Maximising the Benefits of Your Brew
Higham's team travels the world, hunting down single-origin organic coffee beans, testing them for chlorogenic acids, trialling different roasting methods, and testing again. "If you badly roast the coffee, you can destroy 90 per cent of the polyphenols," he says. They experiment with brewing to release as many of the polyphenols as possible. The result is that one cup contains "between 350 and 415 milligrammes" — for reference, a trial of 104 espressos found the highest concentration was 188mg. A cross-section of studies suggests 1,000-2,000mg per day is a good benchmark. And it's worth noting Davis's observation that "we shouldn't underestimate the influence of human interaction on health when meeting friends for a coffee".
