They can raise cholesterol in the heart and may give people a heart attack if they have too much saturated fat.
But if there is something intrinsically dangerous about raising good cholesterol, then the whole approach may need to be abandoned.
The drug, which Pfizer has been developing since 1998, raises so-called good cholesterol.
And it would further state which of the fats raise cholesterol and which do not.
You've no doubt heard of the trouble with trans fats by now (they raise "bad" and lower "good" cholesterol).
Pfizer has also run into unexpected problems with torcetrapib, a drug meant to raise so-called good cholesterol.
Regular exercise will also help lower "bad" cholesterol and raise "good" cholesterol.
You probably heard that eggs can raise cholesterol, but they are also a good source of protein.
Trans fat also raises cholesterol and increases your risk of heart disease.
Still, even at low levels, trans fats do raise bad cholesterol, and no matter how you slice it, that's bad news.