Editor’s note 2/6/2013: Pending an FDA decision, 23andMe no longer offers new customers access to health reports referred to in this post. Customers who received their health information prior to November 22, 2013 will still be able to see their health reports, but those who purchased after that time will only have access to ancestry information as well as access to their uninterpreted raw data. These new customers may receive health reports in the future dependent on FDA marketing authorization.
By Sheel Dandekar
Not convinced that those trips to the gym are making a difference? Think again. In a recent study in PloS Genetics, researchers from Lund University in Sweden found that exercising can change how the DNA in fat cells works.
With the growing number of links found between genetics and health, it is easy to fall into the trap of thinking that your genes determine your fate. That’s just not the case.
Genetics plays an important role in your health, but so do environmental influences. This includes lifestyle factors, which you have control over (e.g. eating junk food, smoking), and factors that may be difficult to control (e.g. the quality of healthcare you receive). To the extent to which we can dictate our environment, we have the power to change our risk for many common diseases
We frequently think about genetics and environment as two completely separate things – the classic nature vs. nurture debate. However, it turns out that genetics and environment can’t be neatly separated.
A growing list of studies show that environmental factors can lead to lasting “epigenetic” changes, such as modification of the DNA base. To understand how this can happen, consider that your DNA is just a blueprint, a set of instructions for making the various things your body needs. Not all parts of the blueprint are actively being read in every cell. A complex system of switches controls which parts are being decoded, and which parts remain unread. Environmental factors can epigenetically modify DNA to determine whether or not those switches work. For instance, a famous study of children conceived during times of famine found that a chemical modification known as methylation can last for decades.
So do these epigenetic changes only happen in extreme environmental conditions, such as famine? The Lund study showed that simply exercising can change how the DNA in fat cells is read through the methylation of key genes. They recruited 31 generally healthy but sedentary men and had them follow an exercise program for 6 months. The program consisted of 1 session of a 1 hour spinning class and 2 sessions of a 1 hour aerobics class each week. As one might expect, a number of clinical measurements (waist circumference, cholesterol, blood pressure) improved after 6 months of working out. More surprisingly, when they compared the DNA from the men’s fat cells before and after the program, they found that significant portions of the DNA sequence had been methylated. In particular, a number of genes suspected to play a role in obesity and type 2 diabetes were modified, and the authors suggested that these modifications might drive differences in metabolism in fat cells.
In demonstrating that exercise can alter DNA methylation in fat cells, this study raises some interesting questions. Previous work has shown that exercise can lead to epigenetic changes in muscle cells. What other types of cells show epigenetic changes after exercise, and what exercises are best? Finally, how long do these epigenetic changes last?
Further research may help to answer these questions and maximize the benefits of exercise. For now, take solace in the fact that your genetic code is just one factor to consider in your overall health, and that many other factors remain under your control.