Diversity is the Key

We are the fattest nation in Europe and we just got even fatter.UK citizens on average put on nearly a kilo in three months since March according to our survey of over a million and a half people using our covid-19 symptom app. As well as being the fattest, we probably have the worst diets; we eat proportionally the most ultra-processed food (around 50 percent of our meals), and snack more than any other European nation. We are only beaten by the US in this regard. This is acutely topical because of Covid.

Our guts are back in the headlines because of Covid and Boris’s waistline. It is no coincidence that obesity, age, diabetesand social deprivation are all strong risk factors for having severe forms of Covid. They are all associated with poor gut health and weak immune systems. Poor gut health in modern terms means a lack of diversity of our gut microbe species. Too few good guy beneficial microbes and you no longer keep your immune cells in good shape and this means you respond to food badly (with excess inflammation, and sugar and fat spikes) and have a weaker response to infections like covid-19 where you have more severe and lasting symptoms .

Highly processed food diets are bad for us - especially when labelled misleadingly as “low-fat, low carb, low sugar” etc. These high levels of ultra-processed foods have now been shown in clinical trials to increase hunger and the amount people eat. They also reduce thediversity of our gut microbes and poor gut health, which cause yet more metabolic problems. The good news is - unlike your genes, you can improve your gut health and microbes. One in five of us actually improved our diets and gut health during lockdown by snacking less and eating more thoughtfully.

Although we share 99.5 % of our genes with each other we all havea unique set of microbes and even our identical twins are different. This means picking the right foods for you as an individual can be tricky. But now we can predict your response to individual foods via the new science of personalised nutrition which involves blood and stool tests and wearingglucose monitor. But before these commercial tests are available (end of the year viajoin.zoe.com) we can all improve our gut health in simple ways.

The first is to increase our fibre uptake - most of us need to double it by eating more plants to properly feed our microbes. Then try to vary what plants you eat by experimenting more and not having the same kale smoothie.The optimum number of plants we found in our studies was around 30. This sounds daunting but includes nuts, seeds and herbs which can easily be sprinkled on salads and yogurts. Select plant foods high in polyphenols as these are like rocket fuel for the microbes and finally have a daily shot of fermented food- whether its high quality cheese, yogurt, kefir or kimchi. You can also experiment with skipping meals like breakfast and see how you feel and try out restricted time feeding to give your guts a good rest of 14 hours overnight.

Boris’s reluctance to do the obvious and extend the successful sugar tax to other sweet products and ultra-processed foods and focussing on calorie labels is due to the successful lobbying of the rich and powerful food and drink companies, who aren’t going to disappear any time soon. They will continue to try and indoctrinate us with guidelines andmisleading food labels suggesting that low fat, low sugar, low calorie foods are all healthy regardless of quality. Don't be fooled. Eat for your microbe’s benefit and you won’t go far wrong.

Tim Spector is Professor of Genetic Epidemiology at King’s College London, Lead of the Covid Symptom Study app (covid.joinzoe.com) and author of The Diet Myth ( Orion 2016) and Spoon-Fed: why almost everything we have been told about food is wrong (Jonathan Cape, Vintage, 27 August 2020)

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