A diet rich in polyunsaturated fats—found mainly in vegetable oils and fish—seems to protect people against cardio-vascular disease. A new study that measured blood levels of these fats in older adults now lends further support to this observation.

The report, in the June 17, 2015,

Circulation

, included more than 4,200 Swedish men and women without heart disease who were 60 years old when they joined the study. Researchers then tracked the participants’ deaths over the following decade and a half. People with the highest blood levels of these beneficial fats were less likely to die from heart disease or any other cause than those with the lowest levels. Measuring the blood levels of these fats may be more reliable than asking people to recall what they ate, the researchers note.