Complement is recognized as an important, humoral defense system involved in the innate (nonspecific) recognition and elimination of microbial invaders, other foreign particles or molecules, and antigen-antibody complexes from the body. The present invention makes use of the surprising notion that the handling of lipids by the body, rather than its antimicrobial activity, is the primary and most ancient function of the complement system. Consequently, atherosclerosis as observed in disorders associated with disturbed lipid metabolism (familial combined hyperlipemia (FCHL), postprandial hyperlipidemia, hypertriglyceridemia with low levels of HDL cholesterol, and insulin resistance associated with type-II diabetes and obesity), is ascribed to either genetic or acquired defects in ancient (activatory and/or regulatory) complement components. Based on this new insight, novel preventive measures and treatment modalities of disturbed lipid metabolism are introduced.