Using the data of more than 300,000 people aged 40 to 69 which they gathered from the UK Biobank, researchers from Karolinska Institute in Stockholm used Mendelian randomization for the study. It is a type of statistical technique that uses genetic variation as a natural experiment to find out causal relations between potentially modifiable risk factors and health outcomes in observational data.
With this, they found that there is a causal relationship between BMI and cardiovascular diseases, especially aortic stenosis.
“The causal association between BMI and fat mass and several heart and blood vessel diseases, in particular aortic valve stenosis, was unknown. Using Mendelian randomization we found that higher BMI and fat mass are associated with an increased risk of aortic valve stenosis and most other cardiovascular diseases, suggesting that excess body fat is a cause of cardiovascular disease,” said Susanna Larsson, lead author of the study.
The study debunks the popular belief that people can still be fat and remain healthy, as long as they keep factors such as blood pressure and blood sugar in check.
In fact, the research found that for every genetically-predicted one unit rise in BMI, there is a six percent increase in the risk for pulmonary embolism. Worse, the one unit rise in BMI could lead to a 13 percent increased risk for aortic valve stenosis. In addition, mutations predicting increases in fat mass was found to have direct relations to increased risk for cardiovascular diseases.
Aortic valve stenosis has the most pronounced connection to the increase in BMI. The researchers found that there is a 46 percent higher chance for overweight and obese people to develop the disease. It is characterized by the narrowing of the aortic valve opening. When this happens, blood flow becomes restricted from the left ventricle to the aorta and may also affect the left atrium.
Some of its symptoms include chest paint, rapid and fluttering heartbeat, trouble breathing or shortness of breath, feeling dizzy, fainting, difficulty walking short distances, swollen ankles or feet, sleeping difficulties and reduced ability to do normal activities. If these symptoms are neglected, this may lead to stroke, atrial fibrillation, heart failure, peripheral artery disease, deep vein thrombosis, high blood pressure and coronary heart disease.
While genetic factors can cause people to become overweight or obese, the researchers emphasized that lifestyle factors are still the cornerstone of keeping a healthy weight, especially with the alarming number of overweight and obese people in the world.
According to the World Health Organization (WHO), in 2016, more than 1.9 billion people in the world aged 18 years and older were overweight. Of these, over 650 million were adults. Moreover, the organization estimates that in the said year, 13 percent of the world’s adult population were obese.
One factor that contributes to the rising number of overweight and obese is the lack of physical activity -- even a simple one such as walking. Inactivity is the new normal for most people today, even to those who are working. A study revealed that of today’s jobs, only 20 percent requires moderate physical activities. This means that one of the reasons why most adults are overweight is they don’t do any physical activity while on their jobs and most are just sitting throughout the work day.
“Our genes can make us somewhat more predisposed to gain body weight but lifestyle factors, such as overeating and lack of physical activity, are the major determinants of being overweight. A healthy diet is the cornerstone of cardiovascular disease prevention, and how much we eat should be limited to the amount of energy required to maintain a healthy body weight,” Larsson added.
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