It is well known that there is a strong relationship between good physical fitness in youth and a lower risk of cardiovascular disease in later life. However, when the researchers adjusted for family factors through sibling analysis, they found that while the link between high body mass index (BMI) and cardiovascular disease remained strong, the association was weaker.The study, conducted by researchers at Karolinska Institutet and other universities, was published in JAMA Network Open.
“This does not mean that fitness is irrelevant,” said Viktor Ahlqvist, a doctoral student in the Department of Global Public Health at Karolinska Institutet and the study’s final author. “We still saw an association, although it was weaker after accounting for factors shared by half-siblings. We also believe that adolescence is a time in life when good habits, such as exercise and healthy eating, are established. ) important period.”
Proving cause and effect is challenging
Many observational studies have previously demonstrated links between various risk factors in youth and cardiovascular disease in adulthood. However, it is difficult to prove whether these associations are causal due to the potential influence of unexplained genetic and environmental factors. So a collaborative team of researchers at Sweden’s Karolinska Institute sought to investigate whether it was indeed possible to prevent most cardiovascular disease in adulthood by lowering body mass index, lowering blood pressure, improving physical fitness or improving muscle strength in adolescence. disease.
Using data from the Swedish Military Conscription Register and other Swedish registries, the researchers identified more than 1 million 18-year-old men and followed them for 60 years. Almost half of them are brothers.
“Our study is more reliable than many other traditional observational studies because it We used sibling analysis.” Drugs. “By doing this, we can examine how the relationship changes when controlling for all shared sibling factors. This includes environmental factors such as childhood environment and half of the genetics.”
High BMI is a strong risk factor
The results showed that high body mass index in late adolescence was strongly associated with future cardiovascular disease, even when the researchers controlled for shared familial factors. However, the association between physical health and cardiovascular disease was much weaker in sibling analyses, suggesting that many previous observational studies may have overestimated the association of adolescent health with cardiovascular health in later life.
“We conclude that of the risk factors studied, high body mass index is the strongest individual risk factor for cardiovascular disease and that efforts to combat the obesity epidemic should continue to receive high priority,” said study co-author Daniel Berglin Daniel Berglind said. Department of Global Public Health, Karolinska Institutet. “Good fitness and muscle strength appear to be less important during adolescence, but physical activity remains important for public health because of the other health benefits it can bring.”
The study examined the association between risk factors at a young age and future cardiovascular disease. Results for other diseases were not investigated. The researchers had no data on whether the participants’ risk factors changed later in life, and they only studied men, making it difficult to extend their findings to women. The draft register also lacks detailed information on certain risk factors for future cardiovascular disease, such as diet, alcohol consumption, smoking, blood lipids, and blood sugar.
The researchers received no specific funding for this study. Co-author Martin Neovius is on the advisory panel for Ethicon, Johnson & Johnson and Itrim, and outside the scope of this study serves as a consultant to the Swedish Armed Forces. No other conflicts of interest were reported.