A good place to start is to read the Primal Blueprint unless you have already read it. Gary Taubes debunks a lot of conventonal wisdom on saturated fat and cholesterol in his book Good Calories Bad Calories. (Which can be very dry and technical, if you want an easier read he just released Why We Get Fat).
All I know is that my grandparents visited the butcher every week for their food. They ate lots of red meat, full fat dairy (I don't think there were other options back then) and eggs. My grandparents even smoked socially and drank liberally. But they never had heart disease or cancer. My grandmother just hit 101 this year and she still doesn't take any type of medication. They might have had stellar genes which I am very thankful for, but the truth is that in the early 1900's people ate a lot of whole foods, meat/poultry, dairy(butter) and eggs. A lot of people smoked during those times as well. But the incidence of heart disease and cancer was way lower than it is nowadays. Now they have all this lowfat crap, a multitude of cooking oils, and more processed food than ever and our rates of obesity, type 2 diabetes, heart disease and cancer is at an all time high.
"If man made it, don't eat it" - Jack Lallane
People say I am on a "crazy" diet. What is so crazy about eating veggies, fruits, seafood and organ meats? Just because I don't eat whole wheat and processed food doesn't make my diet "crazy". Maybe everyone else with a SAD are the "crazy" ones for putting that junk in their system.