A blood test for risk of heart disease?

We know that trans-fatty acids are associated with a higher risk of heart disease. One recent study has estimated an additional 23% risk of developing heart disease for every 2% increase in the amount of trans-fatty acids in one's diet. Yet we also know that people's recall of what they eat can sometimes be unreliable. Researchers at Harvard Medical School recently performed a study to find out if trans-fatty acid intake could be measured via a blood test (Circulation 2007;115:1858-1865).

The study utilized blood samples drawn from 32,826 women in the Nurses' Health Study. All of the samples were from women who were free of cancers or heart disease at the time of the blood being drawn, although 167 women later were diagnosed with heart disease or died of a heart attack.

The analysis of the blood drawn focused primarily on the fatty acids that could be found in the red blood cells themselves as measured by gas-liquid chromatography. Each type of fatty acid was identified as a percentage of the total in each sample. A standard cholesterol screening was also performed for each sample.

After analyzing all the blood samples, the scientists grouped the samples into four increasing levels of trans-fatty acids in the blood cells. By comparison with those women in the lowest fourth, the women with the highest levels of trans-fatty acids in their blood cells were almost three times as likely to develop heart disease! This continued to hold true even when the scientists controlled for such variables as fiber intake, vitamin E supplementation, or the amount of fruits and vegetables the women ate.

What this means for you

This study gives us another tool for measuring risk of heart disease, although it might be some time before it becomes a standard test, if ever. It certainly gives us a good measure of what people really eat versus what they say they eat. In the mean time, read nutrition labels carefully and avoid foods - including fast foods! - that contain trans-fatty acids.

First posted: March 30, 2007