For many years I have been arguing with doctors about natural hormones – on lots of topics – but one in particular has been the fact that women not only have fewer heart attacks than men but when they do they do not have the same impact. It is rare for women to suffer heart attacks before their 50s, but menopause sees the numbers – and risk – increase
Now new research from Queen Mary, University of London sheds light on why women are far more likely to suffer heart attacks after the menopause. It can be traced to our declining estrogen levels, because estrogen keeps the body’s immune system in check. After menopause – when estrogen levels drop dramatically – coronary heart disease rates rise steeply. The study has shown that estrogen works on white blood cells to stop them from sticking to the insides of blood vessels, a process which can lead to dangerous blockages.
The results could help explain why cardiovascular disease rates tend to be higher in men and why they soar in women after the menopause. It’s not yet clear quite how this protection occurs but this study suggests that estrogen has another role. The hormone seems to affect women’s response to infection and injury, by preventing white blood cells from moving out of the blood stream into tissues. This reduces inflammation, part of the immune system’s rapid response. It is now clear that one of the functions that estrogen has in the body is to help stop blood cells sticking to artery walls and forming potentially fatal blockages.
The researchers compared white blood cells from men and pre-menopausal women blood donors. They found that cells from premenopausal women have much higher levels of protein called annexin-A1 on the surface of their white blood cells. The scientists also found that annexin-A1 and estrogen levels were strongly linked throughout the menstrual cycle.
White blood cells play a vital role in protecting the body from infections. When they are activated they stick to the walls of blood vessels. This process normally helps the cells to tackle infection but if it happens too much, it can lead to blood vessel damage, which in turn can lead to cardiovascular disease. However, when annexin-A1 is on the surface of these white blood cells it prevents them from sticking to the blood vessel wall. A key finding of the new research is that estrogen can move annexin-A1 from inside the white blood cell, where it is normally stored, to the surface of the cells preventing the cells from sticking to blood vessel walls and causing vascular damage.
Until recently, experts have struggled to explain why younger women are less likely to develop heart disease and suffer heart attacks. Dr Suchita Nadkarni from the William Harvey Research Institute, Queen Mary, University of London, who led the research, said: “We’ve known for a long time that estrogen protects pre-menopausal women from heart disease, but we don’t know exactly why. This study brings us a step closer to understanding how natural estrogen might help protect our blood vessels. We’ve shown a clear relationship between estrogen levels and the behaviour of these white blood cells. Our results suggest that estrogen helps maintain the delicate balance between fighting infections, and protecting arteries from damage that can lead to cardiovascular disease. Understanding how the body fights heart disease naturally is vital for developing new treatments.”
Estrogen often gets a bad press because of its link to certain cancers and other health problems, but it is when it is out of balance that problems occur. That’s why some women at menopause do need a little extra estrogen as well as natural progesterone: John Lee made it clear that is the balance between the two hormones that it is important to get right.