The findings of a study conducted by the University of Minnesota Children’s Hospital, Minneapolis, leads to the conclusion that just growing up as a male increases the risk of heart disease by the time the young man is 19 years old. The study is based purely on physiology and does not take into account any lifestyle factors.

Led by Antoinette Moran, MD, professor and chief of the pediatric endocrinology and diabetes division of the Minneapolis children’s hospital, the research indicates a very early start to the protective advantage women have with regard to heart disease.

Once in adulthood, people of both genders are at increased risk of heart attack when some specific factors are present - obesity, smoking, physical inactivity, elevated blood pressure and/or cholesterol levels, and insulin resistance, which is considered a pre-diabetic condition characterized by ineffective insulin metabolism. Moran’s team turned to children aged 11 through 19 to track how early in life these changes take place.

The research team monitored 507 children from Minneapolis for the study. Twenty percent of the children were African American, 80% white, and 57% male. All children in the study were considered healthy, with no incidence of diabetes or major illness of any kind.

When the study began, all the children were 11 years old and body composition, blood pressure readings, and lipid levels were similar for both genders.

During adolescence, normal changes increased both the body composition and the waist sizes of the boys and girls. With the onset of puberty, the boys lost body fat while the girls gained it. By age 19, there were four risk factors for cardiovascular disease that became significantly different between the boys and girls:

– Triglyceride levels had become higher in the boys but had decreased in the girls.
– The “good” cholesterol, high-density lipoprotein (HDL) decreased in the boys but increased in the girls.
– Systolic blood pressure increased in both genders but markedly so in the males. Systolic blood pressure is the top, or first, number read. It measures the pressure generated by heart contractions.
– At age 11, the boys rate of insulin resistance was lower than the girls’ but, by age 19, the trend was reversed, with 19-year-old boys exhibiting more insulin resistance than 19-year-old girls.

“Bad” cholesterol (low-density lipoprotein, or LDL) and total cholesterol counts did not constitute any significance with regard to gender as did the other risk factors studied.

Researchers were especially surprised to find such high risk in the boys, particularly at a time during normal development when they were gaining muscle mass while losing fat. Excess body fat is one of the strongest risk factors associated with cardiovascular disease. Even with the gender-related protection females enjoy, excess fat diminishes that protection. Saying “obesity trumps” all other factors, Moran says anyone who is obese - boy, girl, man, or woman - faces increased risk of cardiovascular disease.

Because women seem to enjoy a natural protection against heart disease from puberty to menopause leads the research team to suggest it’s the sex hormones that contribute to the protection. The research team would like to see more studies undertaken to determine if it’s the estrogen that’s protective or the testosterone that is detrimental.

Full details of the Moran study can be found in Circulation: Journal of the American Heart Association. Some funding for the study was provided by the National Institutes of Health.

Source: American Heart Association