Oestrogen linked to risk factors for heart disease in young men
A study led by researchers from Poland and the UK has shown that naturally occurring levels of oestrogen in young men are linked to risk factors for heart disease. The so-called male predisposition to cardiovascular disease has largely been attributed to genetic factors. The effect of hormone levels has also been linked to coronary artery disease, atherosclerosis and stroke but findings have been somewhat contradictory. Until now, the correlation between oestrogen levels early in life, when subjects are healthy and exhibit no signs of disease, and specific cardiovascular risk factors has not been established. In an effort to understand why cardiovascular disease is so much more prevalent in men than in women of the same age and ethnicity, a team of researchers led by Dr Maciej Tomaszewski of the University of Leicester in the UK examined data from a group of 933 healthy, young men with an average age of 19 participating in the Young Men Cardiovascular Association (YMCA) study. Specifically, they examined circulating hormone levels, particularly estradiol and estrone, and looked for associations with risk factors for heart disease. The researchers hypothesised that increased concentrations of oestrogen in men early in life would be associated with factors known to lead to heart disease later in life, such as increased blood pressure, body weight and a bad lipid (cholesterol) profile. They found that levels of estradiol and estrone, which together make up oestrogen, were linked directly to total cholesterol: estradiol was associated with under-production of 'protective' (HDL) cholesterol and estrone with overproduction of 'detrimental' (LDL) cholesterol. Their findings indicate that the relationship between this cholesterol imbalance and increased circulating oestrogen levels was independent of the effects of other sex hormones (including testosterone), age, body weight, blood pressure and other factors. Levels of circulating cholesterols in adolescence have been shown to be good predictors of cardiovascular risk factors later in life, and estradiol levels vary only slightly with age in men. The association between estradiol and lipids seems likely to continue into adulthood, and may explain the correlation between estrogens and cardiovascular diseases such as atherosclerosis that are often seen in older men. The age of the subjects was a crucial factor in the current study, as previous research on hormone levels and cardiovascular disease has focussed on middle-aged or elderly men. Dr Tomaszewski and colleagues looked at the effect of hormone levels at a time in the subjects' lives when they wouldn't normally exhibit signs of cardiovascular disease. In older men, the confounding effects of aging, medications and other illnesses make it very difficult to establish a direct relationship between hormone levels and disease. While genetic, environmental and hormonal factors all contribute to cholesterol levels and hormone production, each plays a modest role in the development of cardiovascular disease. However, the findings of the current study have clinical significance. The study concluded that 'an association between oestrogens and lipids in men has its roots early in life, before any overt clinical manifestations of cardiovascular disease', and that 'increased circulating concentrations of estrogens may have negative impact on the cardiovascular risk profile in men'. Dr Tomaszewski commented that it is unclear why these oestrogens are perceived to be cardio-protective in women while they seem to increase the risk of cardiovascular disease in men.
Countries
Poland, United Kingdom