Moreover, since the discovery of the role of LDL cholesterol (LDL-C) in the pathogenesis of atherosclerosis, the two hypotheses have become tightly linked by a number of molecular and cellular processes.
[2] Other hypotheses have associated the role of infectious agents (e.g. cytomegalovirus, Chlamydia pneumoniae and Helicobacter pylori) in inflammatory responses in the arterial wall.
[citation needed] The first phase of the inflammatory process is marked by the accumulation of lipid and low-density lipoprotein (LDL) particles beneath the endothelium.
[14] Epidemiological studies designed to test the relationship between high SFA/PUFA ratios and CHD mortality have tended to produce mixed results.
[15] Yet a large population study from Sweden covering roughly the same time period showed no association between fat intake and CHD.
[16] The early studies associating the ratio of dietary SFA and PUFA with TC levels led the American Heart Association (AHA) to promulgate a set of dietary guidelines which included the recommendation to replace saturated fats found in dairy and meat products with polyunsaturated fats found in natural vegetable oils such as those derived from "corn, cottonseed, and soya".
[17] Despite the lack of uncontrovertable epidemiological evidence of their effectiveness, these initial guidelines received widespread acceptance among the medical community in the US.
Moreover, the guidelines now recommend minimizing the intake of partially hydrogenated fats while increasing the consumption of fish and other sources rich in omega-3 fatty acids.
[19] (Much of the evidence presented to support this claim of a large increase in incidence of CHD in the early part of the century is anecdotal.
They stress benefits of dietary SFA, citing presence of natural antioxidants in animal fats, while encouraging people to avoid foods containing processed vegetable oils.
Their considerations are not limited to CHD, they point to an entire litany of inflammatory disorders which can be linked to diet and the consumption of processed vegetable oils.