UK researchers have shown that increasing body mass index (BMI) worsens cardiovascular health, even in people as young as 17.
They applied two genomic approaches called Mendelian randomisation (MR) and recall-by-genotype (RbG) to look for a causal relationship between BMI and left ventricular mass index (LVMI) — a commonly used marker of heart disease — and higher blood pressure in 17–21-year-olds.
Using data from the Avon Longitudinal Study of Parents and Children, they studied 7,924 people in the MR component and another 418 people in the RbG component.
The researchers found that in both sets of analysis, increased BMI caused increased blood pressure, greater LVMI, increased stroke volume and cardiac output. Collectively, these indicate that the left ventricle of the heart is working harder to pump blood around the body.
Although BMI is associated with poor cardiovascular health, whether this is due to reverse causation, confounding or bias has not been established in younger age groups.
“It is the first time that the nature of this relationship has been shown in a group of young adults where it has been possible to draw improved conclusions about its causation,” says Kaitlin Wade from the University of Bristol, who presented the data
at the European Society of Human Genetics Annual Conference.
Wade and her colleagues say that the findings support efforts to tackle obesity from a young age to prevent the development of cardiovascular ill-health.
 Wade KH, Chiesa ST, Hughes AD et al. Assessing the causal role of body mass index on cardiovascular health in young adults: a Mendelian randomization and recall-by-genotype analysis. Presented at: European Society of Human Genetics Annual Conference; 27-30 May 2017; Copenhagen, Denmark.