Cooked fats are most dangerous and are a direct cause of cancer and here is exaclty why:

Fat is the most dangerous of the caloro-nutrients to be heated. When fats are heated carcinogens are formed. When fats are heated they become sticky. They cause blood cells to stick together which leads to thrombosis (clot) embolism and other blockages (infarctions) like stroke (cerebral infarction) or heart attack (myocardial infarction).

With the frying of fats Acroleic acid and Acroline gas are formed. Source These carcinogens are implicated as absolutely cancerous and maybe more dangerous than tobacco smoke.
So many people think they are eating well but because there is a barrier of sticky fat around the body is unable to absorb anything. Sticky fats cause blood clots.

We will define as a poison any foreign substance that occasions an immune reaction in the body. A defensive action is taken in the body only when it is threatened. An apple does not occasion an immune defensive action, hence it a food. A piece of bread does occasion immune defensive actions like the production of white blood cell ‘vacuum cleaners’ to defend itself against the intrusion. The average American has 50,000-70,000 bouts of leukocytosis before they die from the cancer or cardiovascular problems that result.

A sensor system also warns the body if anything enters the vital domain, which is not food. And it is here where we derive our working definition of the word poison. It is so easy to be an unhealthy vegan! Just keep eating fried foods and refined sugars.