A nationwide study of 2.3 million Israeli adolescents examined from 1967 through 2010 has found a clear association between elevated body-mass index (BMI) in late adolescence and subsequent cardiovascular mortality in midlife.

The unusually broad scope of this study provides further support for findings of previous studies suggesting such an association. The results were published on April 13, 2016 in the New England Journal of Medicine.

“Our findings appear to provide a link between the trends in adolescent overweight during the past decades and coronary mortality in midlife,” said the paper’s senior author, Prof. Jeremy Kark of the Hebrew University-Hadassah Braun School of Public Health and Community Medicine.

“The continuing increase in adolescent BMI, and the rising prevalence of overweight and obesity among adolescents, may account for a substantial and growing future burden of cardiovascular disease, particularly coronary heart disease,” Kark said.

BMI is a calculation of weight divided by the square of height. People with a BMI of 25 to 29.9 are considered overweight (84th to 94th percentile), while obesity is defined by a BMI of 30 or more (95th percentile).

Kark and 11 other researchers, including Dr. Hagai Levine from the Braun School and Dr. Gilad Twig of Sheba Medical Center, examined a national database containing height and weight values of 2.3 million 17-year-old Israelis recorded over a 43-year period.

They assessed the association between BMI in late adolescence and 32,127 deaths among the cohort in midlife from coronary heart disease, stroke and sudden death by mid-2011.

The results showed an increase in risk of death from coronary heart disease at BMI values above 20, even within the “normal” range of 18.5 to 24.9 BMI.

As BMI scores increased into the 75th to 84th percentiles, there was an elevated risk of death from coronary heart disease, stroke, sudden death, while the rates of death per person-year were generally lowest in the group that had adolescent BMI values in the 25th to 49th percentiles.

Higher rates also were observed among those considered underweight, below the fifth percentile (less than 18.5 BMI).

What’s the connection?

The researchers offered two possible reasons for the apparent influence of adolescent BMI on cardiovascular outcomes in adulthood. One is simply that overweight adolescents tend to become overweight or obese adults more prone to cardiovascular disease.

They also speculate that early obesity could exacerbate the effects of obesity-associated metabolic abnormalities later on, such as high plasma lipid or lipoprotein levels, increased blood pressure, impaired glucose metabolism, insulin resistance, and coronary and aortic atherosclerotic plaques.

However, weight is not the sole risk factor. Several other associations were revealed by crunching the data.

For example, low residential socio-economic status was associated with a greater risk of coronary heart and stroke mortality, whereas the reverse was noted for sudden death. Height and years of schooling were inversely related to all four cardiovascular endpoints, indicating that taller and better-educated people are at less risk.

Country of origin also seems to impact health. The data showed that people of Israeli and Asian origin were at excess risk of coronary heart disease mortality; Asian and North African origins were at higher risk of stroke mortality; and USSR, Asian and North African origins were at a greater risk of sudden death and total cardiovascular disease mortality.

Scientists involved in this research are affiliated with Sheba Medical Center in Ramat Gan, the Israel Defense Forces Medical Corps, Sackler School of Medicine at Tel Aviv University, Hebrew University-Hadassah Braun School of Public Health and Community Medicine, the Israel Ministry of Health, and Mount Auburn Hospital and Harvard Medical School in Massachusetts.