EAT DIRT FOR YOUR HEALTH

How to get your gut balance right with a little help from soil

Until recently, the gut and what goes on in it was most definitely not a conversation topic. But now, digestion is a full-blown industry, with shelves of probiotics in health-food stores and digestion-improving manuals in book shops. Gut by Giulia Enders (£12.99, Scribe) sold more than 1.5 million copies in Germany, but was also a surprise bestseller in the digestion-shy UK.

So why is the gut having a moment? It’s not a moment, it’s the future, says Tim Spector, professor of genetic epidemiology at King’s College London and author of The Diet Myth: the Real Science Behind What we Eat (W&N, £8.99). As the lead investigator of the British Gut Project, which, as part of the global Human Microbiome Project, has looked at swabs of more than 3,000 guts, he knows. The microbiome – the bugs that live in our gut – is, he says, effectively “a new organ – it’s a whole other dimension to nutrition we hadn’t considered before”.

It was only in the past few years, with the advent of DNA testing, that the 100 trillion cells in our guts could be identified – and analysed into several thousand species and strains of bacteria, viruses and fungi. It has also been revealed that your microbial mix is unique to you, like an inner fingerprint. Not only is the microbiome essential

for the immune system and digestion but also, says Professor Spector, differences between people’s microbes explain why some people get fat, get allergies or immune problems and a whole range of chronic diseases, including diabetes and heart disease, even mental health conditions: “And why one diet doesn’t fit all: why the same food eaten by different people will have different effects.”

What you want in your gut bugs, says Professor Spector, is diversity. But what most of us have got – due to sanitisation, antibiotic overuse, processed food and indoor lives – is the opposite. “It looks like diversity has been dropping steadily for the past 40 years,” he says. “It’s likely that the average healthy person is actually abnormal in terms of their gut microbes.”

This, says US gastroenterologist Dr Robynne Chutkan, author of The Microbiome Solution (Scribe, £14.99), is why we have ‘dysbiosis’, a name for the various gut issues – constipation, diarrhoea, pain, gas – that have become a virtual epidemic. “There is no probiotic diet pill that can change your microbiome,” Dr Chutkan says. But new research suggests growing a healthier microbiome could be as simple as exposing your body to soil, getting a dog and other lifestyle changes…

Soil is teeming with microbial life – we need to consume around 500mg of earth each day

EAT EARTH

Look at the piles of fruit and vegetables in the supermarket – most will have been washed of any traces of where they grew. Soil is teeming with microbial life, the kind our guts evolved coming into contact with. Dr Josh Axe, US doctor of natural medicine and author of Eat Dirt (Harper Wave, £14.25), has dubbed earth “vitamin dirt” and says we need around 500mg of earth a day – the equivalent of a supplement capsule or “the same amount your average child consumes when playing outdoors”. That’s good news if you grow your own vegetables: you will be exposed to soil through your more muddy harvest, and also through the digging and weeding involved*.

HAVE A PET

Living with dogs is also helpful: not only is that lick full of bacteria, but they bring in diversity via their coats and feet, so don’t be too quick to clean it all up. The antibacterial triclosan, found in some handwash, toothpaste and bleach in cleaning products, may protect us from bad bugs, but it also kills the good ones.

KEEP MOVING

Being active may also affect the microbiome. In the British Gut report, Professor Spector writes, “The strongest factor found to date affecting the richness of the gut microbes in more than 3,000 people was the amount of exercise they reported performing” – although this hasn’t been separated out from healthy eating, he says.

FILL YOUR PLATE WITH PLANTS

Beneficial bacteria live on fruit and vegetable fibre. “By doubling your fibre intake and increasing your vegetables, you can change your gut in days or weeks,” Professor Spector says. “We think there are some microbes in there just getting by on occasional scraps of apple, but if you feed them more apple, they will start blooming.” To keep it simple, follow Dr Chutkan’s rule: “Eat at least one at breakfast, two at lunch and three at dinner.” New studies also show that the chemicals in plants – polyphenols – only work if you have the right bacteria to process them. If you haven’t, your kale and quinoa will, quite literally, be going to waste.

TAKE PROBIOTICS

Mention gut health, and probiotics (so-called friendly bacteria) will likely spring to mind. But, says Professor Spector, they are misunderstood. “Probiotics don’t take over your gut, the vast majority just pass through,” he says. What they do is help your existing good bacteria to thrive. But which one to pick? “At the moment, we don’t know any one species that is going to do you good, so my advice is to go by trial and error,” he says. “Buy a reputable make, and at least five to ten billion colony units in each daily dose.” For example, Bio-kult, Optibac or Symprove. Professor Spector prefers to get his probiotics through fermented foods. Try kefir, sauerkraut, kimchi and raw miso paste, and apple cider vinegar, which isn’t a probiotic, but encourages the growth of them. To get the full bacterial benefits, eat small portions of these daily.

COOK FROM SCRATCH

Besides being full of fat and sugar, which starve good bacteria, additives found in processed foods, such as some preservatives and sugar substitutes, wipe them out. For example, some emulsifiers, used in foods such as mayonnaise, bread, ice cream and cake to combine oil- and water-soluble ingredients, have been shown in studies to damage the gut lining. “Emulsifiers are just one of many chemicals in processed foods that are nasty for gut microbes,” says Professor Spector. Your cravings for junk may even be caused by bacteria asking for their favourite foods. “It’s a vicious cycle,” Dr Chutkan says. “The more sugar, starch and fatty food you eat, the more you cultivate the microbes that are better at harvesting energy and pulling a lot of calories from food.”

Doubling your fibre intake and increasing vegetables can quickly change your gut