You can't go without it, which is why the body has a mechanism to make its own if you don't eat it. It is found normally in our brain tissue, bile, blood, nerve sheaths, liver, kidney, and adrenal glands. Virtually all cells of the body form it, as many of the membranous structures of all cells use it. Better indicators of cardiovascular disease are serum triglycerides and serum homocysteine, both now found to be more closely related to cardiovascular risk than cholesterol. Having an M.D. behind a name doesn't mean that individual is trained in nutrition.
Therapeutic nutrition takes a LOT of outside study.
The practitioners who actually use high-dose nutrient therapies without ulterior motives are rare. You can't go wrong reading anything you can find from the likes of Jonathan V. Wright, MD, Alan Gaby, MD, Doris Rapp, MD, Ben Feingold, MD, Lendon Smith, MD, William Crook, MD, Adelle Davis, Carlton Fredricks, and others. Now he admits that he was wrong, and that you need them. What you have to do is read, read, read, everything you can get your hands on, quacky, conventional, whatever, remembering that medical schools are controlled by the drug companies, and the medical literature that doctors read is similarly controlled. Then make up your own mind about what sounds reasonable to you.