Female sex hormones are to blame for the greater number of heart attacks in men.
What is good for women may not be so for men. A set of chemicals that shield the members of the fairer sex from cardiovascular complications may have a contrary effect on men, a recent study reveals.
Female sex hormones — estradiol and estrone, collectively called estrogens — are normally produced in very small quantities in the male body, as a by-product of the male sex hormone testosterone. Ironically, while they are responsible for a healthy libido in men, these hormones may also be making them more prone to heart diseases compared to women of the same age, particularly if the hormone levels are high.
An international team of researchers, led by Maciej Tomaszewski of the University of Leicester in the UK, recently showed that higher levels of female sex hormones in the blood are to blame for the vulnerability of men to heart disease and stroke.
Though regarded as female hormones, they play an important role in men such as nitric oxide release and building bone mass and so on, says Tomaszewski.
Estrogens circulate in the bloodstream of every man; they are essential — for healthy libido, improved brain function, protection of the heart and strengthening of the bones. Some men, albeit a very small percentage, are known to have higher levels of the hormones.
The team, comprising scientists from Australia, Poland, the US and the UK, enlisted 933 young healthy males from the southern Polish town of Silesia, the average age being 19 years.
The study, published online recently in the journal Atherosclerosis, shows that these naturally occurring sex hormones do not directly cause the life-threatening condition. They work through other risk factors, some predominant ones being genetic predisposition, body mass and alcohol consumption. For instance, the levels of estrogens are linked to increased levels of bad cholesterol (LDL-cholesterol) and low levels of good cholesterol (HDL-cholesterol). When the levels of estradiol were high, the total cholesterol in the body was found to be high, but the levels of bad cholesterol remained low. On the other hand, the higher the estrone level, the greater were the levels of total cholesterol and bad cholesterol.
According to the scientists, a significant aspect of the study is that it showed that certain sex hormones might be important risk factors of heart diseases in men — even before they present symptoms of coronary artery disease or stroke.
“Thus, men with the highest concentrations of estrone and estradiol may have the highest level of cardiovascular risk as their levels of detrimental LDL-cholesterol are high whilst their cardio-protective HDL-cholesterol is low,” says Tomaszewski who is with the department of cardiovascular sciences at Leicester University.
Most importantly, the demonstrated associations between cholesterol and estrogens were independent of other sex hormones (testosterone and androstenedione), age, body weight, blood pressure and other potential confounding factors.
“Our data suggest that higher levels of estrogens may have a negative influence on the lipid profile of men early in life, before the apparent onset of cardiovascular disease,” says Tomaszewski. But, he adds, it is too early to propose estrogens as markers of cardiovascular risk.
Why natural endogenous estrogens that are generally seen as cardio-protective in women increase cardiovascular risk in men remains a mystery, say the scientists.
Sources: The Telegraph (Kolkata, India)