There isn’t strong enough proof to say that eating less saturated fat and more vegetable oils will definitely prevent heart disease, according to this big review.

The official advice to eat less fat to avoid dying of heart disease isn't backed up by the long-term studies of large groups of people.

We don’t have enough reliable data yet to say if swapping butter for bread or olive oil makes a difference in heart disease risk, because not enough studies provided the right information.

We don’t know yet if swapping butter for bread or olive oil makes a difference for heart health — there just isn’t enough solid data from long-term studies to say for sure.

Some big studies that looked at lots of people who ate less saturated fat didn’t find that they lived longer or had fewer heart attacks, which makes people question why we’ve been told to avoid foods like butter and cheese for so long.

Eating more saturated fat from meat, butter, or cheese doesn’t clearly make people more likely to die early or get heart disease or diabetes, but the science isn’t strong enough to be sure.