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

Stacey Morrison finds out just how reliable home-based DNA tests for health and fitness really are.

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

Apparently.

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.

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."

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.

"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…

Go to this episode on rnz.co.nz for more details