The secret to a healthy gut – an extra cup of coffee
Our guts are a battleground for bacteria, good fighting bad for supremacy. Scientists have produced the most in-depth analysis of these bacteria yet and the results are surprising.
Our guts are a battleground for bacteria, good fighting bad for supremacy in their universe. It is from within this environment that microbes create anti-inflammatory compounds that have been shown to help with everything from regulating the immune system to aiding digestion.
Fuelled and maintained by the food we eat, these beneficial gut bugs are known to be powerfully protective, but research from scientists at Zoe, the personalised nutrition company run by the co-founder Tim Spector, professor of genetic epidemiology at King’s College London, has unearthed significant new information about the health-boosting potential of our microbiome. Previously, researchers had identified 30 key bacteria linked to health and diet but by using cutting-edge DNA analysis software in the form of “metagenomic shotgun sequencing” the Zoe team have produced the most detailed map of gut bacteria to date.
“We discovered a total of 4,993 new microbes that nobody had ever come across before,” says Dr Frederica Amati, research associate at Imperial College London’s WHO Collaborating Centre for Health Education and Training and a nutrition scientist on the Zoe team.
“The top 100 of them are most strongly associated with health outcomes of interest, good and bad, and nearly all of the new bacteria are better at predicting health than bugs we knew about previously,” Amati says. “That’s not to say associations with existing gut bugs were wrong, but that these newly discovered types have a much stronger influence on health.
“We can see how strong the association is between intake of certain foods and the microbiome and work out how that correlates with health. There was a clustering of the new good bacteria in people who love to eat nuts or eggs, for example, which tells us these foods are particularly important for gut health.”
Initial results from what is the largest study of its kind were presented at the EMBO/EMBL Symposium on the microbiome in Heidelberg, Germany, last week and will be the subject of a scientific paper to be published next year.
The team have enough evidence to show that the bottom 50 bad bacteria from the newly discovered batch are driving obesity while the top 50 good bacteria are strongly linked to a lower BMI. “Certain bacteria are driving this association with weight gain,” Amati says. “But it doesn’t end there as we are seeing similar links with cardiovascular disease, stroke, vascular dementia, type 2 diabetes and colorectal cancer.”
How our gut microbes interact with pharmaceutical drugs is also being investigated because the team suspect that some gut bugs can dramatically alter how people absorb and dispose of medication.
“We’re interested to learn why many medications don’t work for some people as they are expected to,” Spector says. “People may have the wrong microbes or a different response [to medication].”
It may explain why even something like paracetamol affects people differently and why some are more sensitive to its effects and to toxicity from the medication than others. In time they plan to produce finer prescriptive detail, showing how many cups of espresso or handfuls of walnuts may be required to provide specific improvements in wellbeing. But even their early findings give clear pointers about the foods we should be eating more of, some of which might seem surprising. “It’s not all about plant-based and vegan eating,” Amati says. “Our results showed that some animal foods are beneficial and that variety is hugely important.”
Of course the usual suspects, wholegrains and leafy greens, are important for gut health, but these are the other top foods shown to boost levels of the newly discovered good bugs in your microbiome.
Coffee
An unexpected hero of the gut health world, black coffee has a “wildly strong” correlation with positive microbe outcomes, Amati says. A paper to be published by the Zoe team next year will outline how important it is for the microbiome, but she recommends drinking a few cups a day. “You can really tell if someone drinks coffee when you check their microbiome sample. It correlates very highly with the good bugs in the gut.”
Drip and espresso are the methods that extract the most polyphenols, the beneficial dense chemicals that are a type of antioxidant, from coffee beans, but any type of coffee or method of making it is likely to be gut-friendly, including instant, which might surprise the coffee snobs.
“Coffee is generally very good for the gut and while there might be minute benefits between a fresh coffee grown in the Himalayas or coffees that are grown pesticide-free compared with mass-produced jars, there are not huge differences between varieties,” Amati says. “A lot of people think freeze-dried coffee is not good, but actually it is and because of the process of freeze-drying the polyphenols in coffee stay intact, so good old Nescafe and the like are fine.”
Avoiding sugar or syrups, which are not gut-friendly, is the golden rule.
Dark chocolate
Chocolate can be eaten in moderate amounts without guilt provided we choose the dark variety. “It’s great news that some of our good gut bugs absolutely love dark chocolate,” Amati says. “It scored very highly on health measures thanks to its high levels of antioxidants – some types contain more than red wine or green tea – and also the fibre it contains.”
An average 100g bar of 70 per cent cocoa dark chocolate contains about 11g of fibre, which gut bacteria digest to flourish, alongside disease-fighting nutrients including iron, magnesium and copper, as well as manganese, calcium, potassium and zinc.
Last year a study in the Journal of Nutritional Biochemistry showed that consuming 30g (about three squares) of 85 per cent dark chocolate daily altered the gut microbiota of a group of healthy adults in a way that produced improvements in their mood.
Choose chocolate bars with the fewest ingredients, especially sugar, and don’t overdo it. Three to four squares is enough, Amati says.
Yoghurt, cheese and eggs
Yoghurt, made by adding live bacteria to milk, is a probiotic food that has frequently been shown to be beneficial to gut health, with a 2021 Purdue University review of more than 100 studies confirming its benefits as a health tonic. “There’s little doubt it is beneficial provided you select a plain yoghurt with live or active cultures,” Amati says. Fermented cheeses are a more surprising gut-booster, largely thanks to the bacteria added during the manufacturing process to convert the naturally occurring milk sugar, lactose, into lactic acid.
“Blue cheeses such as stilton are a good example of a variety containing plenty of bacteria,” Amati says. “But aged cheddar, parmesan and gruyere are also a good choice.” People who consumed more eggs were also found to have higher levels of the new good bacteria in the latest study, possibly down to the small amounts of omega-3 fatty acids they contain.
Oily Fish
Mackerel, sardines, trout and other oily fish are rich in omega-3 fatty acids, in particular EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), that have been strongly linked with gut health.
In previous research from the University of Nottingham involving 876 middle-aged female twins it was shown that those with higher levels of omega-3 in their blood had not only a greater variety of bacteria in their gut, but also more of the good stuff, regardless of how high their fibre intake. The latest study confirms that oily fish intake boosts the presence of the newly discovered beneficial bugs, Amati says, and we should aim for two to three servings a week.
Unsalted nuts and seeds
Last year, a team of Zoe researchers from King’s College London showed that just a handful of almonds daily increases the production of butyrate, a type of short-chain fatty acid that boosts gut health by acting as a fuel source for cells in the colon. Almonds and other nuts and seeds, provided they are unsalted, also help to regulate absorption of nutrients in the gut and keep the immune system in balance.
“Nuts contain fibre, unsaturated fatty acids and polyphenols that our gut microbes love as well as important nutrients such as vitamin E, magnesium and selenium,” they said. “We think from the new studies that eating a variety of different types from walnuts and pecans to sunflower seeds and pistachios is the best approach.”
Fruits
“There’s so much evidence that increasing fruit intake is protective for gut and health,” Amati says. “Yes, fruit is naturally sweet but the sugar contribution it makes is not a problem when you consider the fibre, polyphenols and nutrients as well.”
Fruit also helps to keep you satiated, she says, and is a far better snack than many people think provided it is eaten whole. “Fruit juices are best avoided,” she says. “But aiming for a variety of berries, apples and other fruit will be beneficial.”
