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Conversations at Scarfes Bar: Dr Tim Spector

An interview with genetics professor and popular author Tim Spector

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You really are what you eat, Dr Tim Spector tells Matthew Bell

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Every time Dr Tim Spector sips his coffee, something unique happens. It is different to what happens when I drink my coffee, or you drink yours. This is because, as he explains, every person has a trillion different microbes lining their gut whose composition is unique to them. Forget genetics – what makes us truly individual are the billions of microorganisms lining our intestines all doing different things. It explains why one person might eat a cream cake and put on a pound, while another could eat ten and stay skinny.

The study of microbes is a surprisingly new field of science. We all know that we are what we eat, but only in the last ten years have we begun to realise that what goes on in our stomachs can affect everything from our mental health to our weight. ‘Realising that your gut can produce brain chemicals that can make you happy or sad opens up new possibilities,’ he says. ‘Instead of giving someone antidepressants, why not change their diet for a month first?’

Dr Tim Spector

Tim came to this field of science through the study of genetics. He started out as a rheumatologist, specialising in bony spurs in knees, on which he was the world expert as a young man. But he realised he didn’t want to spend his life focusing on one thing. So he moved into the study of twins in 1992, setting up TwinsUK at King’s College London, a research project that has grown to become one of the most data-rich ongoing studies, generating one thousand science papers in 27 years.

One of the fascinating things to have emerged is the realisation that the organs of identical twins do not behave in identical ways, despite sharing 99.99 per cent of their genes. This led Tim to look more closely at the composition of their gut bacteria, which are only 33 per cent the same. ‘While your genetic make-up doesn’t change, your microbes vary depending on your environment,’ he says. ‘There seems to be a randomness to it: some microbes like living in certain people and not others.’

In 1999 Dr Jeffrey Gordon– ‘the father of the microbe’ – wrote a paper positing that gut bacteria were not all bad. ‘Until then everyone had been trying to nuke ’em. We took antibiotics like Smarties, which were considered the fix-all for everything. But Gordon showed that they could perhaps be linked to our immune systems. They thought our guts were somehow rotting, and that yogurt cleansed the system. So they got the treatment right. Some people still believe we’re full of toxins that have to be got rid of, but in my view that’s nonsense.’

Understanding this field of science could help tackle some of society’s biggest problems, from obesity to depression and even autism. ‘It’s slightly daunting because it looks like every disease could be associated with gut bacteria, and we don’t yet have the skills to pick them apart,’ he says. ‘It’s a whole new field that needs new specialists.’

Tim admits to being a ‘jack of all trades’, and that some scientists treat him with disdain. He has published two popular science books, most recently The Diet Myth (2015), and his next book, Spoon-Fed, will claim to bust 20 food myths with the strapline: ‘Why almost everything we’ve been told about food is wrong’. Does this sensationalist approach help or does it add to the confusion? ‘Possibly,’ he says. ‘I think you’re right, people are confused, they are getting messages from all over the place. But hopefully my book will show people where the messages have been coming from, mainly the big food companies.’

Tim blames the rise in obesity on the unfettered growth of multinational food companies. ‘We were still eating well until the mid-1970s,’ he says. ‘That’s when you start to get ultra-processed food, which was when these food companies grew to become the colossal forces that they are today.’ But the rise of convenience food is a global phenomenon. Why does Britain have it so bad? ‘Britain has no food culture, so we have been highly susceptible to the marketing of fast food and snacking. It’s why we eat more ready meals in the UK than the rest of Europe combined.’

And it’s not just because we’re busier and more prosperous that our diets suffer. He points to the example of South Korea, which has transformed in 40 years from a poor country to one of the richest and yet there is no obesity crisis. ‘The reason is that they have a very strong food culture,’ he explains. ‘They worship the national dish – kimchi, which is fermented vegetables and extremely good for you.’ Even when people try to champion healthy eating in schools, like Jamie Oliver, he is ridiculed for meddling. ‘He was doing absolutely the right thing. But then the press turned on him, and he was accused of elitism – “Jamie’s trying to ban our chips”.’

Tim believes cooking should be taught in schools as a basic life skill, like reading or writing. ‘We laugh at cookery classes, but it’s incredibly important that people know how to prepare food.’ Life may be too short to stuff a mushroom, but it’s worth knowing how to do it, and perhaps one day, thanks to microbes, what exactly it’s doing to you.

In Brief

Glass of wine or green tea? Glass of red wine

Rolling hills or seaside? Seaside.

Power breakfast or languorous lunch? Langourous lunch.

Cat or dog? Dog – because of the microbes.

Town or country? You need both.

Sharp suits or cosy knits? I guess I’d have to be a cosy knit.

Tim Spector was a speaker at Weatherbys’ 2019 Creating the Future Conference. To see his talk live please visit or to listen to the podcast, visit


Nicholas Coleridge / Jay Rayner / Caroline Coon