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Genetic testing puts your health in your hands

A medical breakthrough in genetic testing reveals that diet and lifestyle can change how your genes behave.

06 March 2012
by Gillian Warren-Brown

If you could take a quick and painless test to find out if you are predisposed to certain diseases, would you? Would finding out you are predisposed to cardiovascular disease leave you wondering if there’s anything you can do about it, or would you be catapulted into making healthy lifestyle changes?

Nutrigenetics is a new field that studies the effect of genes and their interaction between diet and health. And nutrigenetic tests are now available to the general public, which can show you if you are at risk of disease. Professor Maritha Kotze, researcher and lecturer in the Department of Pathology at Tygerberg Academic Hospital, says many people adopt the attitude: "I can't help it, it’s in my genes". But what this relatively new field has shown is that your DNA does not have to become your destiny.

Yael Joffe, registered dietician and co-author of It’s Not Just Your Genes! (BKDR) says for a long time scientists thought we had little control over the expression of our genes, that we were stuck with whichever gene variants we received from our parents, along with the resulting benefits and disadvantages. "Now we know there’s plenty you can do to intervene, effectively changing the potential behaviour of your genes."

It works like this: someone who has a fiery temper won’t be blowing off steam all the time. But provoke them, and their temper will flare. So, too, our genes may be programmed to behave in a certain way, but they need to be ‘switched on’ by interacting with their environment. You may have the genetic potential for raised cholesterol levels – but those genes will only ‘act out’ if they’re stimulated or inflamed by your diet and lifestyle. That’s why cutting down on saturated (animal) fat, which tends to be bad news for cholesterol levels and heart health, can make a difference.

Your secret code revealed 

As human beings, we have about 25 000 genes in our DNA. Because our bodies need to do more or less the same things to stay alive, we share the same basic set. However, our individual genes come in slightly different versions, called gene variants. It’s these little differences that make your eyes brown and your husband’s green.

While the genes that control the colour of your eyes (and other physical features) are clearly not ,affected by diet and lifestyle, many other genes are influenced by the food you eat, the environmental toxins you’re exposed to and the effects of stress. Even then, these genes don’t cause disease, they simply indicate your susceptibility to chronic conditions such as heart disease, diabetes or osteoporosis.

Having a nutrigenetic test is a straightforward procedure. All it takes is a swipe of a sterile swab inside your cheek to collect cells. From there, the lab takes over and decodes snippets of your unique genetic combination.

Your DNA health report suggests lifestyle choices to suit your unique genetic make-up, so if you are at risk of high cholesterol or insulin resistance that might lead to type 2-diabetes, you would be advised to avoid saturated fats, possibly up your omega-3 fatty acids, keep your blood sugar stable, and follow a low glycaemic load (GL) diet.

A nutrigenetic test might also relieve confusion when faced with shelves full of supplements. Which ,ones do you really need? By looking at how efficiently your body assimilates vitamins, such as the Bs, nutrigenetic tests can indicate where you might need a little more support than your diet alone can provide.

Knowledge is power 

Discovering what your future health might hold seems like a good idea. But it can be a two-edged sword: it empowers you with knowledge and you can no longer claim blissful ignorance. To prepare you – so you don’t feel overwhelmed by the information, but motivated to take action instead – Professor Kotze emphasises the importance of pre-test genetic counselling. A counsellor explains what genes will be tested, what effect they have and what the implications are if the variant has a negative impact on your health.

"When you know what’s needed to compensate for a specific gene deficiency, you can add it, so the gene doesn’t end up driving the disease process. You have that power," says Professor Kotze. She’s quick to point out, though, that there are no guarantees. Making the appropriate lifestyle changes may not prevent a disease from developing, but it can certainly reduce the risk.

While there are clear benefits to having personalised inside information on which to base your plan of action, experts all over the world are also interpreting it as a bigger-picture shift in healthcare. Dr Michael Mol, CEO of the Sportron Nutritional Supplement Group (and well-known presenter on the TV show Top Billing & Hello Doctor) sees it as nothing short of a wellness revolution. "While conventional medicine looks for signs of disease that are already present, genetic profiling looks at predictive indicators that show the potential for certain diseases that have not yet appeared," he says. "Imagine that you no longer call your GP when you’re sick, but rather she calls you to remind you to keep exercising and to eat more fish because of your predisposition to cardiovascular disease, as seen on your genetic profile. Now that’s healthcare!"