High levels of blood fats raises stroke risk in women

By Lilian Anekwe

BMJ Group News

What do we know already?

Fats in the blood are called lipids. All the fats in foods you eat are changed into lipids called cholesterol, or another type called triglycerides. We know that if you have high levels of some types of lipids in your blood, they can build up to form fatty deposits along the inside of the blood vessels. These clog up your blood vessels, making them narrower. This condition is called atherosclerosis. It is harder for blood to flow through narrowed blood vessels and this puts you at risk of heart disease.

Researchers analysed an ongoing study of 82,000 women aged between 50 and 79, and looked at 972 women who had a stroke and 972 women of a similar age and ethnicity. The women all had their levels of triglycerides, ‘good’ high-density lipoprotein (HDL) cholesterol and ‘bad’ low-density lipoprotein (LDL) cholesterol measured. The researchers calculated if there was a link between lipid levels and strokes.

What does the new study say?

Of all the blood lipids measured, it was only triglyceride levels that raised the risk of stroke. Women with the highest triglyceride levels had a 56 percent higher risk of stroke than women with the lowest amounts of triglycerides in their blood. This risk occurred even after the researchers accounted for things we know can raise stroke risk, such as age, whether women were smokers, their weight, how much exercise they took and whether they had high blood pressure or diabetes.

How reliable is the research?

This study only looked at women, who were of mostly the same race and ethnic background. We don’t know if the results apply to other ethnic groups, or to men. Previous research has suggested that women with high levels of triglycerides in their blood have a higher risk of heart attacks and strokes than men with similar triglyceride levels.

The researchers only looked at one type of stroke, called ischaemic strokes, for which people were admitted to hospital - they did not include mini-strokes (transient ischaemic attacks), or other types of stroke. We don’t know if the risks are the same for these.

The design of this study meant women only had their blood lipids measured once, at the start of the study. But the study lasted an average of eight years, over which time it’s possible that women may have started medications that changed their blood lipid levels and so affected their risk of stroke, but the researchers did not account for this when estimating risks.

What does this mean for me?

This study suggests that, in older women, high levels of triglycerides in the blood can raise stroke risk. Interestingly, high levels of other blood fats such as cholesterol did not have the same risks. The researchers say this is the first study to address these questions and try to measure these risks.

We know that people who exercise regularly have lower levels of triglycerides in their blood, as regular high-intensity exercise encourages your body to use up extra triglycerides stored in your fat cells. So regular exercise and eating a healthy diet is a good way to reduce your risk of stroke.