Eating eggs yolks is almost as bad for your heart as smoking, new research suggests.

Consuming three or more egg yolks a week increases chances of atherosclerosis, according to scientists from Western University. That is when fat, cholesterol and other substances build up on the walls of arteries and form hard structures called plaque.

This plaque can then block the arteries, restrict blood flow and potentially be fatal. Sometimes it breaks into smaller bits and gets into smaller blood vessels or the lungs, Medical Daily reports.

Egg yolks can be two thirds as bad as smoking, the researchers’ claim.

“It has been known for a long time that high cholesterol intake increases the risk of cardiovascular events, and egg yolks have a very high cholesterol content,” said Prof David Spence, from Western University.

Researchers analysed lifestyle data from over 1200 men and woman aged about 60 who were attending a vascular prevention clinic in London. The participants had ultrasounds to measure plaque in their arteries.

The area of plaque increased with age, but people who smoked cigarettes or ate more than three yolks a week had more build-up, according to the paper published in the journal Atheroslerosis.

“What we have shown is that with ageing, plaque builds up gradually… but egg yolks make it build up faster – about two thirds as much as smoking,” Prof Spence said.

“In the long haul egg yolks are not ok for most [people].”