Overweight causes heart failure - large study with new method clarifies the association
An international research team led by Swedish scientists has used a new method to investigate obesity and overweight as a cause of cardiovascular disease. Strong association have been found previously, but it has not been clear whether it was overweight as such that was the cause, or if the overweight was just a marker of another underlying cause, as clinical trials with long-term follow-ups are difficult to implement.
A total of nearly 200,000 subjects were included in the researchers study of the causality between obesity/overweight and diseases related to cardiovascular conditions and metabolism, which is being published for the first time in PLOS Medicine. The goal was to determine whether obesity as such is the actual cause of these diseases or whether obesity is simply a marker of something else in the subjects lifestyle that causes the disease.
The present study was carried out within the framework of the major research consortium ENGAGE, which brings together more than 35 studies and more than 130 co-authors. The study was coordinated by Erik Ingelssons research group at Uppsala University in collaboration with Karolinska Institutet and Oxford University.
These scientists studied whether a gene variant in the FTO gene, which regulates the appetite and thereby increases the individuals BMI, is also linked to a series of cardiovascular diseases and metabolism. The risk variant is common in the population, and each copy of the risk variant increases BMI by an average of 0.3-0.4 units. Since an individuals genome is not affected by lifestyle and social factors, but rather is established at conception, when the embryo randomly receives half of each parents genome, the method is thus called Mendelian randomization. To achieve reliable results a large study material was needed, and nearly 200,000 individuals from Europe and Australia participated.
The results show that an increase of one unit of BMI increases the risk of developing heart failure by an average of 20 per cent. Further, the study also confirms that obesity leads to higher insulin values, higher blood pressure, worse cholesterol values, increased inflammation markers, and increased risk of diabetes.
The role of adiposity in cardiometabolic traits: a Mendelian randomization analysis.
PLoS Med. 2013 ;10(6):e1001474