Ep105: Tim Spector – Microbiome vs Genetic Responses to Diets

In today’s interview I get to speak with Professor of Genetic Epidemiology and Director of the TwinsUK Registry, Tim Spector, on how our own gut microbiome affects our response to different diets.

Diet and nutrition are a complex issue encompassing numerous factors. How one person responds to a certain food can vary greatly to another, even with closely related individuals.

Tim’s study with identical twins really illustrates this point perfectly and sheds some light on factors that affect our health and how we respond to foods.

In previous interviews we talked about the importance the microbiome has on various aspects of our health.  Today, we talk more about what the twin studies have shown and why we should be moving away from generalised advice and focus on personalised nutrition.

I really enjoyed this interview with Tim who shares how the latest microbiome research is shaping new developments. It is exciting to think how in the future these new discoveries will make individualised nutrition advice accessible to everyone.

Special thanks to Tim for joining me on the show.

Enjoy the episode!

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Guest’s Links

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Show Notes with Timestamp Links

Find summarised highlights of what we talk about during the interview.

Use the clickable timestamp links to jump directly to those points in the audio file below:

[00:19] – Introducing Tim Spector, a Professor of Genetic Epidemiology and Director of the TwinsUK Registry at King’s College in London. He is also the author of several science books including The Diet Myth: The Real Science Behind What We Eat and his forthcoming book called Spoon-Fed.

[01:09] – Tim explains that The Diet Myth is a suitably vague term to encompass all of the problems in understanding diets and many of the myths and false beliefs around them. Why has the advice we’ve been given failed?

[03:28] – Tim has spent many years working with identical twins and studying the differences between them. While they are genetically identical their microbes are not that similar. Could that be why they don’t suffer from the same diseases?

[05:16] – While genes are important and account for about 50% of everything, we might have overestimated their importance at an individual level.

[07:01] – The power of the microbiome could explain the individuality in our responses to the environment even if we don’t have the same genes. Tim explains how thousands of genes contained in the gut microbe produce all kinds of different chemicals.

[08:39] – Most science in the field of nutrition is focused on averages. Tim explains how guidelines and rules based on this are complete nonsense. People are starting to wake up to the power of the individual.

[11:43] – How do we help people at the individual level? Tim talks about the DIETFITS study and coming up with a simple test to point them in the right direction. He also explains how the PREDICT study (to be published soon) showed an eight fold variation when given a standard meal.

[15:46] – The aim is to build a prediction model that would be able to give individuals a personalised score on the state of their gut microbiome, how you respond to sugars and blood fats. Through an app, it could then give you personalised food scores and advice.

[17:10] – Tim explains that the medical profession is generally poorly equipped to give out nutritional advice. Food is a complex issue and goes deeper than even the best generally accepted advice.

[19:09] – In the PREDICT study they are also able to compare the influence of genetics vs the influence of gut microbes and other factors about the individual. Important factors include the circadian rhythms, time of day, previous meal, length of fast etc. Is how you eat as important as what you eat?

[22:10] – Tim explained how they stacked lots of different lab tests and real time data to truly know what works best for different individuals. However, now they are piloting a home-use version of this, that everybody can do.

[24:39] – The first thing that will become available in the US will be a free app. By entering certain variables into the app a rough personalisation will be generated. Tim explains how with more people using the app more data is available, resulting in more accurate advice.

[30:04] – Tim explains there are numerous interesting little tips and insights people can gain from this data even if they have perfect scores, e.g. meal timing and intervals.

[31:56] – OMAD eating trend seems to be more inline with how our ancestors probably ate. Latest data indicates that skipping breakfast might be better for weight loss and helping your microbes recover.

[33:59] – Intermittent fasting can make people feel better. Tim doesn’t recommend excessive fasting but believes the occasional fast can be good for you and that we don’t need to be snacking.

[37:39] – While there are currently no sufficient studies in humans, in animals, microbiome studies show that microbes have a circadian rhythm. An overnight fast gives the gut a chance to recover and create a good community of microbes.

[40:13] – At least half of the drugs tested are influenced by the gut microbes. Tim explains microbes treat all substances the same and will try to break things down into nutrients and use it in some way influencing how effective drugs are.

[45:42] – When does the microbiome difference in twins occur? Tim explains how unstable our microbiomes are during the first three years of life, influenced by the mother, the environment and random events. There is a lot of luck involved.

[48:33] – Tim is in favour of having probiotics in real food everyday as they contain a much wider variety of strains than are found in supplements. He warns of potential harms of synthetic probiotics for some people and explains why caution is needed.

[51:27] – Prebiotics are fertilisers and will enhance your existing gut microbes. They can also be found in real food or be artificial supplements and Tim has similar advice for these as with probiotics.

[52:47] – Tim shares his thoughts on its popularity and the benefits vs problems he sees arising with the carnivore diet. He believes diversity in diet is important for a healthy gut microbiome.

[56:51] – How does where we live affect our microbiome? We do see different microbes in different parts of the world and we also see the gut microbiome changing to the environment it is in. We are a long way away from being able to advise on how to boost specific microbes, most likely they work within a community.

[1:01:04] – For anyone wanting to find out more and follow Tim look for him on Twitter and Instagram. Also, for anyone in the US who wants to take part in the pilot studies visit the joinzoe.com website or search for the PREDICT study. Tim’s book Spoon-Fed is coming out in May 14^th 2020 in the UK and can be pre-ordered on Amazon.