The problem with DNA testing for personalised nutrition and health



This was published 5 years ago

The problem with DNA testing for personalised nutrition and health

By Sarah Berry

Personalised nutrition and health has been hailed as the future of food and lifestyle health.

The idea is that we can have our DNA and microbiome tested and end up with a diet and lifestyle plan tailored to our unique health profile and address anything from weight issues to gut health, pregnancy problems to chronic disease.

Health is not one-size fits all but personalised health is not quite here.

Health is not one-size fits all but personalised health is not quite here.Credit:iStock

In fact, one new DNA test in the UK, from Pure Genetic Lifestyle, promises a 99.97 per cent accuracy in predicting health risks (like how likely you are to get Alzheimer's or heart disease), but will set you back about $2,120.

One British journalist took the test and discovered she was twice as likely as your average Joe to get heart disease but is unlikely to die from a cardiac arrest - heart-warming news.

"Heart disease aside, my results are riveting: as well as assessing my risks of illness – and how to minimise them – the report describes which foods will make me put on weight; the sports that I should be naturally good at; even the medicines my body can utilise and the ones I won't be able to break down," she revealed of her results.

It is indeed riveting, but is it worth it?

The problem with personalised nutrition and health is that often the promise of what it can do is premature.

There are basic tests that can reveal the genetic risk of breast cancer (a la Angelina), allergies and intolerances. But may other health issues are complex and not reducible to our genes.

"The general advice is that we're not quite there yet in terms of being able to take a human genome and predict precisely what's going to be the best outcome for the individual," says Associate Professor Andrew Holmes, a microbiologist at the University of Sydney's Charles Perkins Centre.


One of the reasons for this is that although they can detect certain variations in a gene for instance, there can be multiple causes and therefore multiple approaches.

Holmes says, for example, that if two people had a gene variation or microbiome profile that meant they were more likely to be obese, because the reasons for that variation were different, the same approach would not help both of them and may, in fact, cause one of them harm.

"Common things might work for 30 per cent of the population, but not for the rest," he explains.

Denise Furness, a molecular geneticist, agrees, saying that, at this stage, such testing offers insights instead of clear cut answers.

"It's not an exact science," says Furness who is speaking at the Bioceuticals Research Symposium on 'The Age Of Personalised Medicine' in Sydney in April. "It helps to show why some people can tolerate certain things and others don't tolerate it as well and are going to have health outcomes."

For example, one study last year by Israeli researchers found that different foods (like tomatoes or rice or ice cream) cause blood sugar spikes in some people but not others. By taking a micorbiome sample along with details about an individual's diet and lifestyle, they said they could see how a person responds to various foods and calculate a personalised plan to improve their health.

It does hold promise, Holmes says.

"We ask questions like, can I use my microbiome information to predict what foods will give me a high post-meal blood glucose spike? (which might be helpful in managing diabetes) Or can I use it to predict which foods will help me control my inflammatory response (which might help manage allergies or IBD)? Or can it predict if I have early stages of colo-rectal cancer," he explains.

Whilst it is exciting, he reiterates that microbiome or genetic testing alone is only part of the picture.

For her part, Furness approaches her clients' health issues - many are women who are having trouble falling pregnant - from several angles, trying to pull together pieces of the puzzle, while cautioning against expecting miracles.

By profiling their DNA along with other tests and understanding their lifestyle, she can get a sense of intolerances, nutrients they don't absorb properly and how this, combined with how they are eating and environmental influences may be affecting their chances of falling or staying pregnant.

"There's a misconception that you're going to get genetic testing and it's a magic bullet," she explains.

It's not. "But, it helps to explain why things might be happening."

Despite this, Holmes says personalised nutrition and health will be able to deliver on its promises in the not too distance future - he anticipates between two and 10 years.

"You should not expect to gain any dramatic new insights from [an] analysis that you can walk off and apply to your own lifestyle choices," he says.

"The era of including microbiome analyses in personalised medicine is very rapidly approaching, but not quite here yet for most conditions. If you have a chronic low-grade infection (for example C. difficile) that may be picked up by such an analysis.

"For conditions like type 2 diabetes then these are highly multifactorial and the gut microbiota is just one of many factors that impact your health and treatment options. It is possible that a microbiome analysis alone may identify factors that give new treatment/management choices but it's unlikely. The emerging view is that microbiome data PLUS diet and physiological data is needed to get truly predictive information."

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