23 Mar 2021

DNA: Will a DNA-based diet help you fit your jeans?

From Healthy or Hoax, 7:00 am on 23 March 2021

You can buy just about anything online these days, including the key to living your best life.


dna testing

What can genetic testing really tell us about our health and fitness? Photo: 123RF

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Online DNA tests which claim they can give you insights into how best you can stay healthy and keep fit are growing in popularity.

There are dozens of options available and they cost anything from about $80 dollars for a simple health and fitness genetic test, to hundreds of dollars for tests that give more of a medical overview.

Professor Stephen Robertson, the Cure Kids professor of paediatric genetics at the University of Otago, is really passionate about genomics and believes it holds the potential to sharpen medicine.

“I am continually surprised about the reach of genomics and what it can explain in healthcare,” said Robertson.

But he’s sceptical of how much benefit there is to be had through home-based online DNA testing.

“Because that brings with it the limitations of technology and accuracy,” he said.

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Professor Stephen Robertson Photo: Alan Dove Photography

Robertson is also concerned about the fact the results are coming from an area where there is little regulation. He said there have been cases where DNA has been tested for things like the BRCA gene which is linked with breast cancer.

“And all of a sudden you find yourself with a potentially confronting situation which really hasn’t been generated in an environment which we all feel trust in,” he said.

“So that’s where the rubber hits the road about whether this fascination we have with genetics and what it might hold for us in the future changes, from being recreational into something which can be very impactful and have a sharp edge.”

Robertson also said the understanding of our genes comes from testing of people of European extraction.

“So, for those of us in New Zealand with Polynesian or Māori ancestry, the fit is just completely unknown, there is genetic architecture there that we are ignorant of to an extreme degree.”

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The trick is in which genes you are being tested for. Photo: Pixabay

William Ferguson is a GP with several years experience of using genomics to help individualise treatment for some of his patients.

He said the trick is in which genes are most useful. Ones that have common variants, which affect the underlying drivers of disease and that are well-researched, so you know you can alter their expression through diet, exercise and medicine.

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Dr William Ferguson Photo: Supplied

“Because there’s no point finding out about a gene you can’t do a darn thing about,” he said.

Dr Ferguson said it is also useful to look at groups of genes as there is almost nothing to gain from looking at a single gene in isolation.

Stacey Morrison, host of Healthy or Hoax, took one of the cheaper tests, to see what it could reveal about her health and fitness. She was underwhelmed with the results.

“I felt like I was reading a horoscope,” she said.

This was not surprising to Ferguson given the test only looked at nine genes. But he said a couple of them might hold some useful information.

“Sometimes what you do get out of these tests is a sense of what that person’s priorities really are,” he said.

The problem with these home-based online DNA tests is that most people won’t have a GP to go over the tests with them, let alone an expert like William Ferguson, to tease out the really useful findings.

“This is definitely the future, there’s no question,” said Ferguson, “We’re just a little bit early in the game for it and there’s a lot of stuff flying around out there that probably isn’t that helpful.”

Stephen Robertson is pleased people are interested in genomics and thinks it is healthy to question why our bodies work the way they do. His big concern is that these online tests are just not reliable enough.

Scientist viewing a DNA sequence.

"Understanding genomics is an enormous task and we're only just beginning." Photo: AFP / Cultura Creative

They don’t consider how lifestyle factors nor other genetic drivers like temperament interact and impact on our outcomes too.

“The idea that we can begin to disambiguate this, pull it apart, and have all those different factors itemised and understand how they interact is an enormous task and we’re only just beginning.”