Professor Tim Spector has a straightforward theory: almost everything we think we know about food is wrong. For decades we have been taught that calories are king and the most important thing about our food is where it fits in the neat division of carbohydrates, fats and proteins. Don’t skip meals, we are told. Cut out meat. Eat more fish. Drink eight glasses of water a day. All of this, Spector says, is flawed.
You may know him as the creator of the Zoe Covid Symptom Study, the app that sprung up in March 2020 to track coronavirus symptoms across the UK. Since then, the epidemiologist from King’s College London has been a regular presence on our TV screens, commentating on infection rates and the changing nature of Covid as it has waxed and waned. But Spector’s true passion is nutrition. Specifically, how wrong we have got it.
“There is no single diet that will work for everyone, just as there is no such thing as a superfood or a toxic food,” Spector writes in his new book, Food for Life: The New Science of Eating Well. “Provided it is a real food, there is no such thing as a bad ingredient.” Yet, he says, we are in the midst of a global “food health crisis”, with more people overweight than malnourished for the first time in history. “If everyone ate optimally, we could prevent or delay around half the disease burden of heart disease, arthritis, dementia, cancer, type 2 diabetes, autoimmune diseases and infertility.”
At the heart of Spector’s theory lies the belief that the overriding influence on how we react to food is not genetics, or culture, or ethnicity, but the microbiome — the bacteria in our guts. There are as many bacterial cells as human cells in our bodies. We are, as he puts it, “half human, half bug”, and these bacteria have a huge influence on the way we metabolise food.
This explains why each of us responds so differently to what we eat. Genetically, we are remarkably similar — humans share 99.7 per cent of genetic variation. But we have just 25 per cent of our gut microbiome in common. Spector’s research has shown that even identical twins — who share genes and upbringing, nature and nurture — often have completely different reactions to the same food. “We are all unique,” he writes. “No perfect diet or correct way to eat will work for everyone.”
I meet Spector on the third floor of St Thomas’ Hospital in central London. After the chaotic bustle of the clinical floors below, the department of twin research and genetic epidemiology, which Spector runs, is a remarkably calm place. A pair of identical middle-aged women sit in the corridor awaiting an appointment.
Spector’s office is a large but functional room with utilitarian NHS furniture and a few wildlife pictures on the walls. But the views, through large windows, of the Thames and the Houses of Parliament, are spectacular. Spector, 64, slim and deeply tanned, is wearing a fluorescent pink cycling top with suit trousers. An expensive-looking bike leans against the wall in the corridor outside. He has been here since 1993, when he set up the UK Adult Twin Registry, a project tracking the health of 10,000 twins across the country.
Spector has changed research focus five times in that period, but he has largely been left alone by management. “As long as I keep bringing in grants and publishing papers, they don’t hassle me,” he says. He continued to work as a clinical doctor, specialising in rheumatology, until Covid struck, when he decided to focus on research full time.
I begin by confessing I’m confused by one central contradiction in his latest book. If each of us responds differently to foods, how is it possible to provide any overall dietary guidance? If all our certainties about diet are wrong, if calories are irrelevant and saturated fat isn’t bad for us after all, what on earth should we be eating?
That, he acknowledges, is the challenge and one he has attempted to overcome. “This book is about going into detail on the foods and telling the public enough about them so they can make up their own minds,” he says. “What’s nutrition chemistry about? How does it affect our body and health?”
Food for Life is his third foray into the subject. In 2015 he published The Diet Myth, which introduced the microbiome — at the time a radical new theory. He followed it with Spoon Fed in 2020. “That was all the angry bits,” he says. It debunked the calorie as a meaningful measure of nutrition and took aim at the food industry for misleading consumers. This third book, he says, is an attempt to answer the many questions he gets from readers — is brown bread good for you? Is full-fat yoghurt OK?
“We don’t know everything about every food and every interaction with gut microbes,” he says. “And we probably never will. But we do know certain things.” If you eat food that gives you a sugar spike (and those foods differ from person to person) or if fat hangs around in your bloodstream after meals, “those things are bad”, he says. “If you have a gut that is full of pro-inflammatory, non-diverse species, that’s bad.”
Because there are few one-size-fits-all rules, he examines the latest science on each food type. He explains that berries boost the immune system because they are packed with polyphenols; plants use these chemicals as a defence mechanism and they work wonders for our own defences. Colourful fruit and vegetables — beetroot, blood oranges, aubergines — are great because these colours are a sign of beneficial plant chemicals. Full-fat products are usually better for you than “diet” options, he says — there is little evidence that saturated fat actually shortens our lives, and low-fat alternatives are full of sugar and chemicals. Dark chocolate is better than white chocolate; and the occasional serving of high-quality red meat is no worse for you (and possibly better for the environment) than eating lots of fish, stocks of which are dwindling in our seas.
There are some general principles along the way. Calorie counting, Spector says, simply does not result in long-term weight loss and is counterproductive for health. Fad diets — whether it is 5:2, the paleo diet or protein shakes — are doomed to failure. “Every diet works for 12 weeks, but if you track it for a year they bounce back,” he says.
Exercise is good for mental and physical health — Spector takes that expensive bike in the corridor out for five hours a week — but unless you are regularly running marathons it does little for weight loss.
Most official food guidance, he says, is arbitrary. Drinking eight glasses of water a day — still enshrined in official guidance — does nothing except boost sales of bottled water. Be led by your body, he says; if you are not thirsty, there is no need to drink eight glasses a day.
If the professor has one key principle, it is that ultra-processed food — something that could only be made in a factory, or that is unrecognisable as a “real food”, or that contains dozens of ingredients — is probably not going to be good for your health. Fresh strawberries, for instance, bear little resemblance to a strawberry fromage frais; a corn on the cob has little to do with a packet of cornflakes. “These ultra-processed foods, made up of many chemicals, make us feel hungrier, overconsume, and increase risks of disease and earlier death,” he writes. Cooking for yourself as much as possible using whole, unprocessed ingredients means that at least you know what you are eating.
Spector also advises that people try to eat 30 different plants a week. And he suggests that we eat plenty of fermented foods such as kimchi, kombucha or yoghurt, to boost the gut microbiome.
So far, it sounds like a page out of an Yotam Ottolenghi recipe book. If you are bringing up young children, or struggling with food costs in the midst of the greatest cost of living crisis in a generation, is it really practical to seek out 30 different varieties of fruit and veg a week, or source a provider of high-quality kombucha?
Spector accepts the point. “I’m not saying that I’ve got everybody’s lifestyle sorted,” he says. “I’m giving people the tools and they can then decide how much that means in their life. I’m trying not to be too elitist or saying everyone must do this.”
But he points out that tinned baked beans are full of protein and fibre, frozen peas are packed with nutrients and packets of cheap microwaveable rice can be more nutritious than more expensive dried varieties.
Spector, whose children, Sophie and Tom, are now 32 and 30, says: “For parents of young kids, just getting through the day is the crucial thing. But I do think part of parenting is to teach kids about food.” Children’s menus in restaurants are, he says, an “abomination” and should be banned because children should be exposed to adult food early in life. But, he adds: “I was brought up on a pretty terrible diet and I’m still alive.”
Spector was born in 1958 to a busy professional couple in north London. His father was an academic doctor and his mother a physiotherapist, and life in the family home did not always leave time for cooking. “We used to eat ravioli out of tins — that was a big, big treat for us,” he says. “There were lots of canned soups, lots of chips, fish fingers, sausages. And masses of sweet breakfast cereal. I was a Frosties boy. There were plenty of trips to the dentist.”
“My mum was Australian and we spent some time there. That meant lots of eggs and meat, so diet was slightly improved for the year or two we were there. But this was the Sixties and Seventies — it was a different time. We didn’t really snack, we didn’t have regular soft drinks. So it wasn’t all terrible.”
After qualifying as a doctor at St Bartholomew’s Hospital in London, Spector specialised in rheumatology, treating joint and muscle disorders. But he also developed an interest in epidemiology — an academic discipline in which populations are studied to track causes of diseases and trends in health. He was appointed as a consultant rheumatologist at St Thomas’ but also continued to pursue his passion for epidemiological research, using his twins cohort to look at a range of diseases from osteoarthritis to diabetes.
By the 1990s genetics was emerging as a key field in the study of the determinants of health. “So I taught myself genetics,” Spector says. “It is mainly about learning the jargon. You have to stay at the back of the lecture hall until you can speak the language. And then you can go to the front.”
He became a leading expert in the discipline but after a few years grew dissatisfied. As an expert in twins, he knew that even siblings with identical DNA often had very different health outcomes. “I think we’d sort of hit the peak of genetics. I knew there had to be something more.”
For a while he became fascinated by epigenetics, a field based on the idea that genes are switched on and off by environmental factors, and this can have as much influence on health as the genetic code itself. “I thought that could be the big thing,” he says. “I even wrote a book on it that no one read. It was in theory a lovely idea, but it didn’t quite pan out — the size of the effects weren’t quite big enough. So I was looking for something else. Then the microbiome came along.”
Scientists in the US had started talking about the “gut-brain axis” and the impact of bacteria on functions of the human body. “I went to a few lectures and said, wow, this is going to be huge.”
This epiphany coincided with a dramatic change in his personal life. In 2011, while ski-touring high in the Alps on the Italian-Austrian border, Spector suddenly started seeing double. His blood pressure soared. Possibilities raced through his brain — tumour, multiple sclerosis, a stroke. He was eventually diagnosed with a blockage in the blood supply to the muscle of the eye.
The eye problems lasted three months and in time Spector recovered fully. But it was a wake-up call. He realised he had been putting on weight without noticing. He was 84kg and had put on four inches around the waist. “I was typical of someone going through a health shock,” he says. “It makes you suddenly think about all these lifestyle recommendations on an individual level — I had really only thought about it in population terms before. That was the big switch that, really selfishly, led me to being interested in nutrition.”
At first he tried going vegan, which lasted a month. Then he started experimenting with different types of foods. And then he discovered the microbiome.
Five years ago he launched the nutrition company Zoe with investors from the US — in his words, “two business people from the internet … We raised the money to do two and a half years of research using the twins. Based on those studies we now have a home kit that tests your gut microbes, your blood sugar, your blood fats, and you log all your meals.” The result is a personalised list of foods, with each given a score out of 100. “It is basically saying you should be eating more or less of this.”
The Zoe programme, which launched commercially in the US before the pandemic and in the UK this summer, costs £260 (NZ$518) for the tests and an app, then £60 for a month or £300 for a year of follow-up with a nutritionist. Some 30,000 people have subscribed and 245,000 are on a waiting list. But for those who balk at shelling out this kind of cash — or who are stuck on the waiting list — Spector has printed his own scores at the back of his book, to give an indication of how different foods impact his health.
“I’ve switched my breakfast completely,” he says. “I used to have muesli, low-fat milk, orange juice and tea.” But muesli, according to the Zoe plan, is very bad for him, getting a score of just four out of 100 because it results in a blood-sugar spike.
In winter, when he used to eat porridge every day, he chose jumbo oats, which he assumed were healthy. They gave him a score of 10 out of 100. When he occasionally eats porridge now he chooses steel-cut varieties that need longer to soak and cook, but give him a score of 40 out of 100.
Most days — if he has breakfast at all — he now eats full-fat yoghurt (a key fermented food) with nuts and seeds (packed with polyphenols), and black coffee (which cuts the risk of heart disease). “These small swaps can actually make a very big difference in the long term,” he says.
It is obviously working. Spector insists he is more interested in long-term health than weight. But at 75kg he is carrying a stone less than he was a decade ago, and it doesn’t take more than a glance to see there is no spare fat on his body.
In March 2018 Spector was, again, high up a mountain when he had another scare. This was much more dramatic. He was on a skiing holiday in Georgia with his wife, Veronique Bataille, 62, a dermatologist, but the ski lifts were not working. So they decided to hire a helicopter to get to the top of the mountain.
“I remember thinking the pilot didn’t look terribly confident,” Spector says. “It came down very suddenly — dropped five metres and just tipped over on the side. The rotors sliced through the cabin and I was turned over on my head. It was complete darkness, then we could see smoke and flames in the back.”
The party managed to escape the wreckage and had to wade through deep snow. “I remember thinking in James Bond films it’s 10 seconds before it blows up. But curiously, I was ridiculously calm. I stopped and took a video of it — it was very surreal.”
Two years later Spector again showed his ability to remain calm in the face of a crisis. But this time he had more to show for it than shaky mobile footage. In March 2020, when the pandemic struck, Spector, like almost everyone else in the country, was told to go home. He was cycling back to north London when he decided he had to act.
“I just thought we can’t do nothing,” he says. “My colleagues at Zoe were around the corner.” At first they discussed creating a Covid app to use with the twins cohort. “But I said let’s see if we can offer it to the whole country. So the team stopped working on the nutrition app and started working on the Covid app. We built it from scratch in five days and it went out on the first day of lockdown.” On that first day, one million people downloaded the app. “Eventually, 4.5 million people gave us their data. People just wanted to help.”
In those dark days of March and April — with no Covid testing available outside hospitals and the government flying blind — the Covid Symptom Study was the only reliable tool providing any kind of picture as to where the virus was spreading and how people were affected by infections. But not everyone was thrilled. “The government wasn’t very happy with us,” Spector says. “They had their own app — the contact tracing app — coming soon and they thought people would get confused.”
Eventually, the Office for National Statistics launched a mass testing survey that gave officials a reliable idea of how prevalent the virus was. But with such a big user base, the Zoe app could provide a much more up-to-date idea of how Covid was developing. It also gave a better idea of symptoms. Spector’s team was, for example, the first anywhere in the world to discover that a loss of taste and smell was a key symptom — which led directly to a change in international guidelines. And, when the Omicron variant hit in December 2021, the team realised symptoms had changed again, and people with Covid were reporting milder disease, almost indistinguishable from a cold.
Spector was awarded the OBE for his contribution to the pandemic response, but his experience with government left a bitter taste. “I found all my interactions very depressing,” he says. “The level of command and control in the NHS was shocking — nobody was able to make any decisions. I was working with some people from the Ministry of Defence in the early stages — they had thought they were working in the most bureaucratic organisation on earth until they discovered the NHS.”
Last year Spector agreed to work with the government for a second time, when he was invited to contribute to the National Food Strategy, an independent review led by Henry Dimbleby, co-founder of the Leon restaurant chain. Spector wanted the review to call for the abandonment of calorie labelling on foods and for all products to carry a score of how processed they are. “Countries like Chile just put a black sticker on ultra-processed food,” he says.
Dimbleby’s recommendations — which Spector describes as “fairly mild” — were rejected by the government. The review called for a significant expansion to free school meals, greater environmental standards in farming and a 30 per cent cut in meat and dairy consumption. These were all ignored.
But while depressed by our politicians, Spector is not despondent. “It’s a very exciting time for nutrition,” he says. “After Covid, people are suddenly much more interested in lifestyle, in sleep, in moving house, changing the way they live. If we can take that up and run with it, the message about food gets across. The government isn’t going to change, but ground-up we can change what’s in the supermarkets, we can demand what is on food labels.
“There’s a different way to look at food. Not just what you eat — but how you eat. This really could be a revolution.”
- Food for Life: The New Science of Eating Well by Tim Spector is published by Jonathan Cape on Thursday
Simple steps to a healthy gut
1. Aim for at least seven hours’ sleep a night and exercise regularly — move throughout the day and do something more strenuous twice a week
2. Eat fruit and vegetables high in polyphenols (bright colours are a good sign) and fibre
3. Try to eat up to 30 plant varieties every week, including nuts, seeds and spices
4. Avoid snacking and occasionally fast for at least 12 hours overnight
5. Stick to moderate amounts of alcohol, ideally consuming drinks high in polyphenols. These include red wine and cider
6. Eat less but higher-quality meat and fish
7. Ignore calorie counts and seek out foods with higher nutritional quality for similar calorific value. Avoid ultra-processed foods
8. Eat fungi regularly
9. Foods rich in prebiotic fibres — leeks, onions, artichokes and cabbages — are beneficial for your microbiome
10. Don’t use supplements unless you are ill or pregnant — there is no evidence they work for most people
11. Understand that “food is medicine” and the right diet can be just as effective as many drugs
12. When eating convenience foods, choose the least processed ones with the fewest ingredients
13. Don’t follow blindly by eating what someone else says is good for them — nobody is average
14. Cook for yourself whenever you can
15. Eat something fermented every day — yoghurt, kimchi and kombucha are good examples — and experiment with fermenting
Written by: Ben Spencer
© The Times of London