For decades, scientists and doctors alike have known that excess weight and body fat are risk factors for cardiovascular diseases. However, a new study has discovered that excess weight and body fat can actually cause cardiovascular diseases, rather than just being associated with them.
The study was recently published in the European Heart Journal and is the first to not only prove causation, but the first to use the statistical technique of Mendelian randomization to reach this conclusion. According to the CDC, Mendelian randomization is a statistical method that uses “measured variation in genes of known function to examine the causal effect of a modifiable exposure on disease in observational studies.” Mendelian randomization allows researchers to determine whether the risk factor is the cause of the disease or vice versa and reduces bias in results because external or environmental factors can not impact genetic variants.
Researchers studied 96 genetic variants associated with body mass index (BMI) and body fat mass to estimate their impact on 14 cardiovascular diseases. Data from 367,703 participants of white-British descent from the UK Biobank database were used, of which 46% were men and the mean age was 57.2 years.
The results of this comprehensive analysis provided evidence of a “strong and consistent positive association” between genetically predicted BMI and aortic valve stenosis. In a press release from the European Society for Cardiology, lead researcher Susanna Larson stated: “We found that higher BMI and fat mass are associated with increased risk of aortic valve stenosis and most of the cardiovascular diseases, suggesting that excess body fat is a cause of cardiovascular disease.” In addition, those genetically predisposed for a higher BMI were at increased risk of heart failure, deep vein thrombosis, high blood pressure, peripheral artery disease, coronary artery disease, atrial fibrillation, and pulmonary embolism.
Researchers also discovered that the risk of cardiovascular diseases increased for those genetically predisposed for increases in fat mass. They have a 46% increased risk of aortic valve stenosis, as well as increased risks of ischaemic stroke, transient ischaemic attack, atrial fibrillation, heart failure, peripheral artery disease, deep vein thrombosis, high blood pressure, and coronary artery disease.
The research team stressed that although genetic variants can predispose people to excess weight gain, the most important factors implicated in the development of cardiovascular disease are diet and physical activity. Larson emphasizes this by stating, “Our genes can make us somewhat more predisposed to gain body weight, but lifestyle factors are the major determinants of overweight…People who are predisposed to a higher BMI may need to work a bit harder to maintain a healthy weight.”