Swapping saturated fats like butter for unsaturated fats like olive oil doesn’t seem to help your body remove cholesterol better or change a key protein linked to cholesterol levels — so those things probably aren’t why this diet change helps lower bad cholesterol.

If you swap out butter and fatty meats for oils and nuts, your 'bad' cholesterol goes down, which helps prevent clogged arteries and heart problems.

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.

If you're at risk for heart disease, swapping out saturated fats for healthier fats from walnuts or vegetable oils won't raise a specific blood marker (called Lp(a)) that's linked to heart problems.

Eating walnuts or using vegetable oils instead of foods with saturated fats can lower bad cholesterol in people at risk for heart disease—by about 5 to 7%.

If swapping butter for olive oil doesn’t lower your ‘bad’ cholesterol much, then maybe this common diet advice won’t help you either.