In 2009, the 'bad' cholesterol levels in white American adults were about 7% lower than they were in 2000, which could mean less risk for heart disease — but other factors might have contributed too.

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

If your 'bad' cholesterol is 100 or higher, lowering it more aggressively helps prevent heart-related deaths. But if it's already below 100, lowering it even more doesn't seem to help much — there might be a cutoff where treatment stops adding extra benefit.

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.

About half of the people who have serious heart problems also have low 'bad' cholesterol levels.

Even if your heart looks healthy and you have no major risk factors, higher 'bad' cholesterol (LDL) — even when it's considered 'normal' — is linked to more hidden artery buildup. For every 10-point rise in LDL, the odds go up by about 15%.