Are You Ready For The Genotype Diet?

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We’re always being told what to eat to lose weight, prevent cancer or sleep more soundly. But what if pumpkin seeds and papaya just aren’t doing it for you? Not everybody’s body works the same and the one-size-fits-all dietary recommendations dished up by the media and public health campaigns are starting to look outdated. Instead, some nutrition experts suggest we need to tailor our meals to our DNA with genotype diets. The future of food, they suggest, is in ‘personalised nutrition’.

We’ve known for a long time that everyone processes food slightly differently, but this knowledge is now being supplemented by information about our genes, shedding new light on individual food issues and preferences.

Many of us, for example, struggle to deal with dairy. “Some people have the ability to metabolise lactose – the primary sugar found in dairy – whereas others do not,” explains University of Toronto nutrigenomics expert Ahmed El-Shomey. “Those with an impaired ability end up fermenting it in their colon and that results in diarrhoea, bloating and gas.” Why can’t everyone digest lactose though? Individual genomic data gives us a better insight: those who can’t have a variation in a gene called LCT.

Similar can be said for caffeine. Because of a variation in the CYP1A2 gene, some people can drink four cups of coffee a day with no ill effects while others start to increase their risk of heart disease and diabetes at just two.

On top of your genes, the particular mix of bacteria in your gut can affect your dietary responses. In 2017, Israeli researchers showed that people’s gut microbiomes determined what happened to their blood sugar levels after eating bread. Using only data about a person’s gut bacteria, they were able to predict accurately whether that person’s blood sugar would see a greater spike after eating sourdough bread or ordinary white bread.

Your perfect plate
So does this mean that, very soon, anyone watching what they eat will need a genome sequence and a microbiome profile just to decide what to make for dinner? Not necessarily. We can tell a lot about the way our metabolism works from carrying out straightforward tests – like the blood sugar test – after eating certain foods. These other tests have the advantage of showing us how our body actually reacts, not just how we think it should react based on our genes. This is important because our response to food is a result of the combination of our DNA and our lifestyle.

However, as El-Shomey points out, a genetic test is actually pretty simple these days, compared to, say, a lactose intolerance test, and more useful for long-term planning. “It’s probably the most reliable type of test that can indicate a person’s lifetime metabolic differences,” he says.

It might sound like a futuristic way to make a meal plan, but the future is already here. In 2011, El-Shomey founded the personalised nutrition company Nutrigenomix, which now provides saliva test kits and genotyping services to 8,000 clinics in 40 countries. In the next few years, we’ll likely see more companies offering these kinds of services and a continuing explosion in nutrigenomics research.

Fighting the fat
One exciting area of current research focuses on the ‘fat mass and obesity-associated’ or FTO gene, which plays a role in governing metabolic rate and energy regulation. Back in 2007, a UK-wide study linked the FTO gene to differences in people’s risk of developing diabetes and more recently it’s been shown that it influences how people respond to weight-loss surgery. Now, we’re discovering that variations in the FTO gene also determine whether a person is likely to lose weight on a high-protein diet.

If you think all this tailored nutritional advice sounds like it could cause a headache at the family dinner table, consider what you’re already doing to make your meal your own, says El-Shomey – adding salt after serving up, skipping dessert or taking another helping of veggies. “Families have been personalising each person’s meal for a very long time,” he says. So maybe personalised nutrition is just the next logical step.

Take a test
Today, there are already plenty of companies offering personalised nutrition services and anyone can pay to have their DNA analysed. All you have to do is send a saliva sample off to a lab, where scientists test it for a range of genetic variations that are important in metabolism. The results tell you whether you are any more at risk of certain diseases than the general population and what this means for how you manage your diet.

Nutrigenomix sends out reports to its clients, giving them a detailed breakdown of what their genes say about how their body processes proteins, fats, vitamins and key molecules like caffeine and gluten. Alongside the results, the report provides insights such as “you have a high preference for sugar” and recommendations like “consume 20-30 per cent energy from fat”. Crucially, it’s up to the client to do the rest.