A surprising new genetic study shows that some people with naturally high levels of HDL cholesterol—the supposedly good kind of cholesterol—are at increased risk of a heart attack. Doctors are now further questioning the use of drugs to boost HDL levels while looking to new therapies to reduce heart risk.

For decades we’ve been told to avoid foods high in LDL cholesterol (e.g. butter, bacon, lard, palm oil) and to eat foods that raise HDL cholesterol (e.g. nuts, fish, olive oil, avocados). The truth, it now seems, is far more complicated than that. A Cambridge University study published in Science shows that, for a certain segment of the population, the good kind of cholesterol actually increases their risk of coronary heart disease.