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Questions abound: can DNA tests be useful to those interested in maintaining health?

After reading an excellent scholarly article recently on the “utility” of DNA tests, I thought this topic needs further elaboration. Utility here implies that the knowledge gained from the test enables the doctor / patient to do something different when managing the “condition” or “disease”.

I would like to look at “usefulness” from the perspective of ability to redirect behaviour, motivate active change, adherence to medication and providing specific targets for nutritional intervention (without selling multivitamins) – all as part of pro-active health maintenance, particularly in the high risk individual.

Let’s start at the (simplified) beginning for a second. The subject of Genetics had traditionally been known for detecting high-penetrance conditions – meaning something that is inherited with a high index of probability and thus, not surprisingly, it has always had an ominous ring to it. People still associated DNA tests with “getting bad news” and consequently, the question “Do I want to know?” immediately arises.

The current trend of direct-to-consumer genetic tests developed out of the progressive availability of multigene low-penetrance tests for various conditions that is very common in society, has a tendency to become chronic, does not necessarily lead to disability and death and, importantly, have a lifestyle component. In simple language that means they focus on those variations in DNA associated with diseases where we contribute to the outcome through the lifestyle choices we make. Like choosing to smoke, to eat a high-fat diet, not exercising regularly, not paying attention to our stress levels, etc. The upside implies that we can also choose NOT to contribute to this increased risk.

This relationship between our DNA and our lifestyle needs mention. The genetic code we inherit carries numerous messages about our features and bodily functions. How this message is relayed depends on various factors, of which some is the interaction between genes while others are the result of the influences of our environment on these genes. How effectively every component of our body functions depend on this perfect balance between a fully functional DNA message system and an optimal environment.

Now, this is where things have gone astray in the last 100 odd years. What had been an optimal environment for our genes has changed dramatically. We now generally have calorie-dense diets, high in animal fats and low in fibre and some essential micro-nutrients.  This Western diet is out of sync with our DNA, causing it to malfunction at some points. Similar evidence is arising to link our activity and stress levels to gene expression.

Now, to answer the question “Is a DNA test useful if I want to plan a healthy lifestyle?” I have a few comments. These comments are also made entirely from my preventive health vantage point, and particularly where the focus is on mitigating risk before there is any overt disease.

DNA tests can certainly be useful, although it is not always essential to direct a person in healthy choices. In my experience there are three broad categories of utility. The first is in the healthy individual with a strong family history , mostly in the areas of vascular disease risk, cancer risk and diabetic risk. While family history is the stronger predictor of risk, DNA profiles can guide intervention and motivate adherence to lifestyle change.

The second category is the person with risk factors – smoking , abnormal blood tests, a high waist circumference and / or blood pressure problems. Obviously risk factors are cumulative, so the more there are, the higher the risk and the need for action.

Lastly, I see room for DNA tests in secondary prevention in those who have lifestyle conditions – be it diabetes, high blood pressure, high cholesterol, etc. Now that we move towards personalised medicine, fine-tuning the nutritional intake and activity program will become the focus of all practitioners of preventive health as well as their clients.

We have seen that the mere knowledge of your DNA destiny does not ensure sustained lifestyle changes, but this is only the beginning of future medicine where lifestyle will be tailored to match DNA to maximise longevity and postpone disease.