Even when people with heart disease have really low 'bad' cholesterol, some still have heart attacks — showing that low cholesterol alone doesn’t eliminate all heart risks.

If someone with heart disease has a very low 'bad' cholesterol level when they’re admitted for a heart attack, they might be more likely to die in the hospital or later on — but this link goes away when you account for how sick they were overall.

If someone with heart disease has a heart attack, fixing blocked arteries might help more if their 'bad' cholesterol was already low when they arrived at the hospital.

In middle-aged and older adults in China who aren’t at high risk for heart disease, having either too low or too high 'bad' cholesterol (LDL) is linked to a higher chance of dying from any cause or heart problems — the safest zone seems to be around 106 to 118 mg/dL.

The longer and higher your 'bad' cholesterol (LDL) is, the greater your chance of heart disease — and starting with high levels when young makes it even riskier over time.

For people with heart disease from clogged arteries, getting their bad cholesterol down to around 56 doesn’t cause more serious side effects than staying at 66, and it’s safe to keep it that low for at least three years.