Nutrigenomics: Can DNA be used to change your fitness and diet regime?

Firms are promising that a simple swab of the mouth could hold the key to better health

A diet low in carbohydrates is among the possible outcomes of a DNAFit test (iStock/StephanieFrey )

Just a few decades ago, our genes and what they say about us was largely a mystery. Now, with a quick swab of your mouth scientists can reveal everything from your family history to the diseases that you are susceptible to.

This is all thanks to the human genome project, the biggest collaborative project aimed at better understanding the biology of our species. In the 90s, scientists from the US, UK, Japan, France, Germany, Canada and China worked together to work out the base pairs in our DNA.

Now the technology which this pioneered is becoming more readily available commercially, meaning firms are able to trace a person’s maternal and paternal lineages and pinpoint which regions of the world their ancestors were from.

Meanwhile nutrigenomics services like DNAFit analyse a person’s DNA and their genetic variations to give them a personalised workout and diet plan.

Ideal diet and vitamin and micronutrient intake; a person's carbohydrate and fat sensitivity; lactose and gluten intolerance risk; ability to recover after exercise; salt, alcohol, and caffeine sensitivity as well how prone a person is to of soft tissue injury are all measured.

Olympic athlete Greg Rutherford swears that DNAFit helped him to hone his exercise regime, but it's not cheap: tests cost between £99 to £249.

The kit sent to DNAFit customers (DNAFit)

So I gave it a go. The test involves swabbing the inside of your mouth with a specially-designed cotton bud for around for a couple of minutes, before sealing it in a protective tube and posting it off to the DNAFit lab based in the Norwich. A week or so later I found an email in my inbox containing my results.

As a glutton, I skipped straight to the food report to check my ideal diet. The Mediterranean diet, rather than the “low carb” or “low fat” is apparently the one I should stick to. While I’m sensitive to caffeine and salt, I am more responsive to the positive effect of alcohol on cholesterol. I’m lactose intolerant, more prone to risk of damaging my DNA with smoked and chargrilled meat, but don’t need to up my intake of cruciferous vegetables like cabbages and kale. As for exercise, I err towards being better at endurance activities like road cycling than power-based sports, such as sprinting.

Olympic champion Greg Rutherford with his DNAFit infographic (DNAFit)

To piece together profiles, DNAFit test 45 gene variants in the human body. But, considering there are 10 million variants in the human body, how accurate and useful are the results? I’ve been drinking milk without any issues for over two decades. And most of us could do with cutting down on caffeine and salt. My lacklustre performance at sprinting was also never much of a mystery.

Commenting on whether honing in on 45 variants is enough to gain a deep understanding of what we should eat, Dr Tim Spector, Professor of Genetic Epidemiology, said: “sadly not.”

“Although diet choices are often partly genetic, these gene variants are often associated with risk of allergy or disease," he says. "They explain only a small fraction of the differences between people. There are a few exceptions like for lactose intolerance, coffee drinking or alcohol or coeliac disease but basing diet recommendations on genetic tests not usually helpful."

Instead, he points towards the gut microbiome - which varies widely between individuals - as the best way to personalise a diet.

“Genetically testing your microbes is more valuable than testing your own genes at the present,” he suggests.

The views of Marcela Fiuza a British Dietetic Association spokesperson and dietitian, chime with Professor Spector’s scepticism.

“I think the area of nutrigenetics is one of the most exciting areas in nutrition research,” he says. “By combining genetic information with anthropometrics, biochemical and dietary assessments, we will be able to provide personalised advice and customised diet plans. However, there is still a way to go before we get there. There will be a point where we will know more but for now these tests are only weakly informative.”

“I have not used genetic testing with my clients up to this date,” she adds. “I have had clients coming to me after having done genetic tests in other clinics asking for clarification and advice on their results.”

Dr Turi King, Reader in Genetics and Archaeology at the University Leicester elaborates that there many be difference between populations, and that environmental factors including diet, exercise and smoking can play a larger part that our genes, for instance relating to conditions such as coronary heart disease.

“There’s a lot of interactions going on and it’s often not as simple and straightforward as we might hope.

“But there is no doubt, particularly with the research that is going on, that we will be finding out more and more about what parts of our DNA are involved with diet, exercise and disease in the future.”

Perhaps such tests are best reserved for people like Greg Rutherford, where the minute details of every workout count and a team to decipher the results. Although anything encouraging you to cut down on junk and exercise more can’t be an entirely bad thing.