Too much bad cholesterol in the blood clogs arteries and can cause heart attacks.

When you have too much 'bad' cholesterol (LDL) in your blood, it sticks to the walls of your arteries and builds up like gunk, making them narrow and stiff — which raises your chance of having a heart attack or stroke.

If you're a middle-aged person with symptoms, having higher 'bad' cholesterol (LDL) means you're more likely to have heart problems over the next four years — but only if scans show you already have plaque in your heart arteries.

High cholesterol might not be the main reason for heart disease, and having too little cholesterol could actually be risky — so the old idea that cholesterol causes heart problems might not tell the whole story, especially for preventing heart issues in healthy people.

People with higher levels of 'bad' cholesterol in their blood are more likely to have heart attacks or other heart problems.

Keeping your 'bad' cholesterol really low—below 55 mg/dL—might give your heart and blood vessels the best protection against clogged arteries and heart problems.