Thanks to TV yoghurt ads and the many rows of mini probiotic drinks in chiller cabinets, most of us are aware there’s a host of bacteria – many good, some not so good – living in our guts. And with a recent flurry of diet and lifestyle plans designed to improve health and control weight through revamping your gut bacteria, it’s clear this is an area of science that’s really catching the popular interest. But although we’ve known of the existence of gut bacteria for several decades, science is only just starting to grasp the full ramifications for your health – both body and mind. ‘We’re just beginning to unravel the effects of our gut flora – or microbiome [the genes of the microbial cells] – on health, and it’s very exciting,’ says Dr Robynne Chutkan, gastroenterologist and author of the Microbiome Solution (Avery, £17.87). ‘Everything from our weight to our cravings and even our mood and immune system could be affected by what’s going on with the bacterial zoo inside us.’
Your Five Step Plan
So how to promote more diversity, boost levels of good bugs and reap the health, weight and wellbeing benefits? Here, distilled from the latest research, is a practical five-step guide to rebuilding and recalibrating your healthy gut bacteria, and being healthier and happier as a result.
1 Veg out
Eating lots of veg is a key recommendation from all the new healthy gut plans. In The Gut Makeover, Hyde recommends having at least seven handfuls of produce a day (five veg, two fruit, 20-30 different varieties per week), while Chutkan suggests implementing a 3:2:1 regimen for mealtimes – one portion of veg at breakfast, two at lunch and three at dinner. The reason? ‘A helpful way to think about the relationship between eating plants and gut bacteria is that the plant fibre that can’t be broken down and absorbed by your body ends up feeding your gut bacteria instead, explains Chutkan. ‘That means less food for you (think easier weight loss) and more for your microbes.’
2 Select gut-friendly carbs
In essence, that’s any of the whole grain or unprocessed, types (the fibre advantage again). But to really turbo charge your good bugs, it’s important to include carbohydrates with prebiotics in them (prebiotics include inulin, fructo- and galacto-oligosaccharides and in horticulture terms are like giving your gut bacteria a big dose of organic fertiliser). Foods highest in prebiotic carbs are onions, garlic, leeks, asparagus and Jerusalem artichokes, but you can also find them in bananas (the greener the better) and chicory coffee replacement. Another food with prebiotic properties is the ‘resistant starch’ which forms in significant amounts when starchy carbohydrates are chilled after cooking. To harness the benefits of resistant starch for your bacteria means plumping for chilled potato salad over baked potato, and cooking your pasta and rice ahead, and then reheating (thoroughly) for dinner the next day.
3 Include fermented foods
Different experts have their different takes on which fermented foods to consume, but they all agree that by eating them you can introduce important probiotic (friendly) cultures into your system that help keep the microbiome alive and kicking. The most familiar fermented food is natural probiotic (or ‘bio’) yogurt, while at the more delightful end of the scale, a smelly Roquefort, good strong Cheddar or chunk of Parmesan will also give your good bugs a boost. For a more hardcore (and potent) option, try whizzing kefir into a smoothie (Mlekovita Kefir, £1.39 a litre, tesco.com), a helping of freshly made sauerkraut (from £3.99, theculturecellar.co.uk) or kimchi (from £6.49, theculturecellar.co.uk). Chutkan gives a detailed account of how to ferment your own veg, kimchi-style, in her book.
4 Don’t graze
Giving your gut some down time looks likely to benefit your biome, with a study from the Salk Institute for Biological Studies in California showing that when mice were only allowed an eight-hour window in which to eat they absorbed fewer calories from their food. The eight-hour access groups also had more diversity of bacterial species in their guts than the ad lib groups. Previous research has shown that a period of fasting or calorie restriction beneficially alters gut bacteria, perhaps by avoiding a constant stream of sugar into the bloodstream, which raises insulin levels and might give less healthy bugs the upper hand. If an eight-hour window seems a bit undoable, Hyde recommends giving your gut at least a 12-hour break – in practical terms, not eating until eight in the morning if you finished dinner at eight the night before. Professor Tim Spector goes further, suggesting that skipping breakfast may actually be a healthy strategy for some people (he’s also a fan of the 5:2 regimen). Whatever approach you take, it seems at the very least, it’s important to eat substantial meals that reduce the need to snack in between.
5 Dial down the sugar
The health of your microbiome is yet another good reason to cut down on the sweet stuff. ‘Simple carbohydrates found in soft drinks, baked goods and other processed grains cause undesirable shifts in microbial composition, and can lead to the proliferation of yeasts,’ says Chutkan. Unfortunately, sweeteners such as saccharin and aspartame may not be your microbiome’s friend either – although the significance of the findings to humans have been disputed, a study published in the journal Nature in 2014 identified gut bacteria changes and associated glucose intolerance in mice who were given high levels of sweeteners. For your gut, as well a your general health, when it comes to drinks, it seems water is best.