Will Diet and Exercise Save Us All?

How many times have you been to the doctor and was told that a balanced lifestyle is key for a healthy, disease-free, long life? How many times did genetics take the blame? But do we really know whether genetic risk associated with complex diseases can be offset by behavioral changes? A recent study at the New England Journal of Medicine now brings us some answers. The idea that most human diseases are the result of a complex interplay between genes and environment is not new. Complex genetic disorders, those in which the effects of multiple genes are at play and clear-cut patterns of inheritance are difficult to pinpoint, are particularly influenced by lifestyle and environmental factors. Take heart disease as an example. While one’s own risk of cardiovascular disease increases by 3to 5-fold if a person’s parent is diseased, factors such as diet, physical activity, tobacco use, environmental stress, and host factors such as age and sex also play a significant role in the risk of developing disease. The problem is that quantifying the contribution of each of these factors is tricky. Khera et al. (2016) set up to try to answer the billion dollar question: can a healthy lifestyle compensate for a strong genetic risk of developing disease? Genetic risk in complex diseases results from the combination of incremental effects of a large number of DNA sequence polymorphisms. In the case of coronary artery disease and myocardial infarct—a common and severe complication of cardiac disease—over 50 independent loci have been associated with risk of disease in genome-wide analyses. The aggregate of these risk genes provides has proved useful in defining genetic susceptibility to cardiovascular events. Khera et al. make use of this strategy to stratify the 60,000 subjects in their prospective study into three genetic risk categories: low, intermediate, and high. Then they ask whether baseline heathy lifestyle choices impact the risk of developing coronary events and atherosclerosis. The definition of healthy lifestyle was drawn from the strategic goals of the American Heart Association (AHA) to reduce the risk of cardiovascular in the general population and include no current smoking, no obesity, physical activity at least once