Seasonal Variation in Serum Cholesterol Levels Treatment Implications and Possible Mechanisms

Background: A variety of studies have noted seasonal variation in blood lipid levels. Although the mechanism for this phenomenon is not clear, such variation could result in larger numbers of people being diagnosed as hav-ing hypercholesterolemia during the winter. Methods: We conducted a longitudinal study of sea-sonal variation in lipid levels in 517 healthy volunteers from a health maintenance organization serving central Massachusetts. Data collected during a 12-month pe-riod for each individual included baseline demograph-ics and quarterly anthropometric, blood lipid, dietary, physical activity, light exposure, and behavioral infor-mation. Data were analyzed using sinusoidal regression modeling techniques. Results: The average total cholesterol level was 22