Accumulation of arterial plaque starts in childhood, weirdly enough.
Origin of atherosclerosis in childhood and adolescence
Saturated fats don’t build up in the arteries. Trans fatty acids do. Most foods today are made with vegetable oils, margarine being the highest. Nearly ALL vegetable oils used in food production are hydrogenated to make them solid. This turns the oil into highly unhealthy trans-fatty acids. Also heating fats above 96° F. causes toxic alterations, for instance lipid oxides and aflatoxins, which are carcinogenic. Cooked fats cannot exchange molecules properly. Consequently they often dry and harden over the years in the arterial walls.
They are never the problem 100%. High cholesterol (LDL) with low triglycerides is not a reason to worry. High cholesterol and high triglycerides is a problem. Saturated fats have great benefits especially stearic acid and often times people end up with bad cholesterol even on relatively low saturated fat diets but you know that is the case when triglycerides are also high