Personalised nutrition: 5 things you need to know 

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By The Gut Health Doctor Team

Dr Megan Rossi in a lab looking through a microscope

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Personalised nutrition is getting a lot of attention in the research world and in the media – especially as more and more of us are looking to optimise our health and wellbeing.

But what does it actually mean? It’s essentially the concept that every individual has unique nutrition needs, and therefore ideally needs more targeted nutritional advice based on different personal factors.

This means the one-sized-fits-all dietary guidelines we’ve been used to perhaps aren’t always fitting at an individual level, as we may each react differently to different foods depending on things like our lifestyle (sleep, exercise, etc) and, of course, our GM (gut microbiota, the trillions of microbes living in the gut).

That’s what one study by my colleagues at King’s College London (Berry, et al., 2020) set out to investigate.

The PREDICT Study: Personalised Responses to Dietary Composition Trial

Researchers recruited 1,100 healthy participants in the UK (1,000) and US (100) aged 18-65 years and gave them test meals to eat during one day in a clinic followed by 2 weeks at home at specific times, varying in macronutrients (protein, fat, carbs and fibre). They wore monitors as well as having blood tests and giving poop samples for analysis.

What they found

  • Participants’ blood fats, glucose and insulin levels after meals hugely varied between individuals, highlighting the different responses to identical meals – even between twins. BUT, the research also suggested that responses differed WITHIN individuals too, likely depending on a range of factors including meal context, amount of sleep etc.


  • Meal context had a significant influence – people seemed to have a much higher blood sugar response when eating at lunchtime, compared to eating the same meal at breakfast.


  • This ‘time of day’ factor seemed to influence responses in young people the most, while for those over 60 years old it didn’t appear to have as much of an impact.


  • Genetics appeared to have little impact – meaning lifestyle factors (how much sleep we’ve had, how stressed we are etc.) that we have the power to change can have a powerful effect.


  • When it comes to participants’ GM – you guessed it – they found that eating more plant-based foods consistently was linked with more bacteria associated with health benefits. And while a person’s GM did provide some insight to how a person’s blood sugars responded to different meals, the impact was really quite small. This suggests that looking at someone’s gut bacteria in isolation is not the answer to personalised nutrition.


  • Red wine, oily fish, yoghurt, dark chocolate and eggs were also linked with more ‘good’ bacteria!


Full disclosure

Participants were also asked to fast for 8 hours before their breakfasts and to limit exercise. They were also only drinking still water during fasting periods and to avoid eating for 3-4 hours after their meals – so this could have had an impact on some of the results.


What about those commercial ‘personalised nutrition’ tests?

When it comes to the expensive tests being sold online for your DNA or microbiome, promising to reveal your body’s personalised nutrition preferences, and even ‘protect you from disease’ or ‘diagnose food intolerances’, I wouldn’t recommend them… at least not yet anyway.


While they might be interesting and we’re definitely heading towards more personalised nutrition, we’re not quite there yet.


The science is rapidly progressing and I think in the next few years they’ll be more insightful – so save your money for now and watch this space!


If you’re suffering from gut issues and suspect you might be reacting to certain foods, speak to your GP first before eliminating any foods to rule out coeliac disease or anything more serious.


The one ‘generic’ piece of nutrition advice that still stands? Eat more plants for good gut and overall health!


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