Health & Environment

Does DNA dieting work?

Doubts over losing weight by eating foods that match one's genotypes

 

Amouth-swab test developed by Stanford University in the United States to help determine the dietary and exercise needs of the obese has found supporters as well as detractors in Hong Kong.

The researchers took mouth-swabs from 100 women and analysed DNA for five genes linked to how the body uses fat and carbohydrate.

Their findings allow dieticians to develop suitable diets and workout p l a n s for those who want to lose weight.

The outcome of the study: women who  followed the diets matching their genotypes had almost 3 per cent average weight loss more than their counterparts who did not.

This is because every person reacts differently to food intake and exercises, due to varying levels of sensitivity to carbohydrate digestion, saturated fat absorption, fat metabolism, exercise responsive and biologicial clock.

Accordingly, dieticians will recommend a person with a high sensitivity to carbohydrates to adopt a low-carb diet that emphasises the consumption of protein, fibre and other essential nutrients such as meat, fish and eggs and vegetables.

Ms Joanne Chan, a registered dietician working on this genetic testing programme in Hong Kong, backs this way of dieting.

"The genetic evaluation result would give a clearer picture of your needs and it is backed by science," said Ms Chan. "Most importantly, it prevents you from randomly trying different methods that simply won't work."

Ms Chan especially recommends this DNA diet programme to people who have tried various weight loss schemes but without evident success. According to Ms Chan, these people might have already "messed up" their metabolism.

However, Ms Chan notes the importance of keeping a positive attitude when attempting to lose weight because knowing the genetic risks does necessarily guarantee the success of the programme.

However, other medical professionals, including Professor Juliana Chan Chung- ngor, a medicine professor who specialises in epidemiology and genetic engineering at the Chinese University of Hong Kong, have reservations on this method.

"Genetic testing for specific genes to produce a personalised nutrition scheme is still at a very early stage," she said.

But Professor Chan noted that using genetic markers to identify high risk subjects might be able to bring more intensive lifestyle changes and allow early use of treatment to control the development. This includes understanding the biological causes of diabetes and obesity.

Media critics such as Ms Kelly Crowe, a Canadian medical sciences correspondent, and other researchers have argued that the increasing alignment of scientific research with commercial interests raise ethical questions on the credibility and applicability of the studies.

Dr Ahmed El-Sohemy at the University of Toronto was one of those that benefitted commercially from publishing his findings and selling the genetic dieting method in more than 22 countries through registered dieticians.

He has since set up a private company called Nutrigenomix Inc., which provides information for dietitians to counsel their clients according to their "unique genetic profile."

So the question remains — is this all about science or just yet another commercial packaging?

By Hilary Wu

Edited by Karen Lee

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