The Diet Myth by Tim Spector

The first book I reviewed this year (Gut by Giulia Enders – review here) was a revelation to me. It created a new obsession – to improve my digestion and gut flora by eating better and hopefully losing some weight along the way.

But learning about the anatomy and physiology of the gut from Gut was only half of the equation. You need to combine that with good science about the stuff you put into it!

This is where The Diet Myth by Tim Spector comes in. Spector is a geneticist and physician in London, and runs the British Gut project (more about that later). I went to see Spector talk at the Oxford Literary Festival earlier this month, the room was absolutely packed, and he was fascinating and funny to listen to. His lecture essentially summarised his book The Diet Myth, and was full of excellent key points which the book explains more fully.

Spector’s interest in diet came after he was left with high blood pressure after another medical condition and he decided to eat himself back to health and research how what we eat affects our gut, (remember the gut is where 95% of our serotonin and other body chemicals are made for instance and lays claim to being a second brain – working in the background all the time). He is lucky, for being a geneticist, he runs a large database of twins who help in his research.

He started off by reviewing all the existing best-selling diets – and concluded that, with the exception of the 5:2 diet, they are all fatally flawed because they are based on exclusion.  There is growing evidence emerging that a lack of diversity in your microbiome can affect many of our body processes, including tendencies to obesity etc.  The 5:2 didn’t work for me, but time-restricting is (I have my dinner as early as possible, and skip breakfast at weekends).

He explains more about where our microbiomes originate from. We each have around 100 trillion microbes weighing about 2kg in our guts – and we actually share 40% of our genes with them! Those of us born vaginally get our first gut microbes from our mother’s birth canal – including ones that allow babies to digest breast milk. Those born by Caesarian tend to resemble the skin microbes of the first person to pick them up!  There is proof of this – twins picked up by different nurses can have different gut flora.

Spector’s book goes on to cover all the major food types in turn with some fascinating detail. For instance in the chapter on Carbohydrates – Non-Sugars – he discusses raw foods…

We have continued to evolve during the last million years and those diehards who kept on eating raw food died out long ago – and for good reason – it’s hard to extract sufficient calories and nutrients without cooking it at least a little. With the development of cooking we gradually lost over a third of our intestines, along with the ability to exist on raw food.

He’s not saying that we shouldn’t eat salads, nuts etc favoured by raw food and paleo diets, but they exclude so much else, including the poor old tomato (the pseudo-science says that as it’s a member of the night-shade group of plants, it can cause auto-immune disease – tosh!). You can’t help losing weight on them, but suffer from the hard work of digestion and the restricted variation.

Then there is this new passion for sugar replacements. The only low-cal sugar substitute that doesn’t cause chemical disruption in your guts is stevia it turns out. I’d been using sucralose (Splenda) because I knew it was indigestible due to its long chains, but it turns out it does things like the others (Saccharin and Aspartame) which send the wrong chemical messages to your liver and brain, not telling your body you’re full when you are!  Artificial sweeteners, and emulsifiers too, are bad for your microbes.

As for ingredients like Agave syrup – it’s 70% fructose! Fructose is metabolised differently to glucose and has a different insulin response and sends lower satiety signals to the brain. We must learn to read labels better. (Remember table sugar is about 50:50 sucrose:fructose.)

So what should we eat?

Prebiotic foods – these encourage healthy gut bacteria. They act like a fertiliser in our guts and specifically those high in inulin – a strong prebiotic chemical.  Found in: onions, garlic, leeks, artichokes, chicory and small amounts in bread.

Polyphenol rich foods – these are anti-oxidant rich foods full of flavonols etc. Found in: Fruit, veg, nuts, tea (green in particular), coffee, 70%+ chocolate, beer, red wine, extra virgin olive oil.

Probiotic foods – little scientific proof yet that sufficient bacteria from food supplements reach our lower gut where most of our gut flora live, but we all know that yoghurt (full fat, unsweetened) is good for us, especially after antibiotics or if young or old. Keffir and Kombucha tea are apparently even better, but I’ve never tried them.

Fibre – the hard to digest parts of carbohydrates that we need to get to our lower intestine for the microbes to feed off. We’re talking wholegrain/meal here, plus fruit, veg, pulses, nuts etc.

Less meat – but to exclude it completely does mean you will lack certain gut bacteria, vitamins and minerals.

Superfoods may seem a fun concept, but they are also a marketing con, as virtually every fresh fruit and vegetable is a superfood.

What is becoming clear is that many foods don’t work nutritionally as well in isolation as they do when combined together. Spinach and carrots both contain carotene – which is better absorbed in the presence of the fat in an olive oil dressing.

THE SECRET IS DIVERSITY – YOU ARE WHAT YOU EAT!

Have I convinced you yet?

In his talk, Spector also covered the fascinating but yucky subject of faecal transplants which really work for those who’ve suffered c.difficile infections. But you need to make sure that your “crapsules” come from a thin, healthy, mentally balanced donor, as their obesity or axe-murdering can be passed on through epigenetic effects!  He’s a great speaker if you get the chance to see him.

The Diet Myth is a fascinating book and has opened my eyes to eating better and more diversely. I’ve lost 6kg since the beginning of February by applying many of the concepts within its covers – and am working on the next kilos… (10/10)

P.S.  I’m also considering joining in the British Gut project. For £75, you can get a kit to get your own microbiome analysed and compared and contribute to the research. (You don’t have to collect and send off a stool sample, it’s a bit simpler – it’s not like Gillian McKeith – remember her!?)

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Source: Own Copy

Tim Spector, The Diet Myth (Weidenfeld & Nicholson, 2015), Flapped paperback, 336 pages incl indexes)