If adults eat less saturated fat, they’re probably 21% less likely to have a heart attack, stroke, or other heart-related problems — but it doesn’t seem to change how long they live.

Eating less saturated fat—like butter or fatty meats—doesn’t seem to lower the risk of dying from heart problems or other causes, even after years of doing it, according to a review of nine big studies.

If adults in developed countries eat less saturated fat for at least two years, they’re probably less likely to have heart attacks, strokes, or need heart surgery—about 1 in 56 people would avoid one of these events over four years.

Eating less saturated fat can slightly lower your bad cholesterol, but that doesn’t mean you’ll live longer or have fewer heart problems unless you’re changing other parts of your diet too.

Eating less saturated fat doesn't seem to reliably help people live longer or avoid heart disease deaths, whether they're healthy or already have heart disease.

We don’t have strong enough proof to say whether eating less saturated fat makes heart attacks, strokes, or heart disease deaths more or less likely — the studies we have aren’t very reliable.