RELATION OF SERUM ASCORBIC-ACID TO SERUM-LIPIDS AND LIPOPROTEINS IN US ADULTS

Objective: To examine the relation of serum ascorbic acid level to ser um lipid and lipoprotein levels among a random sample of the US adult population. Methods: Using linear regression, the relation of serum as corbic acid level to serum lipid and lipoprotein levels was examined a mong 5,412 women and 5,116 men enrolled in the Second National Health and Nutrition Examination Survey (NHANES II), 1976-1980. Age, race, bo dy mass index, level of physical activity, level of education, alcohol intake, and dietary energy, cholesterol, and fat intakes, and other p otential confounders were included in the multivariate models. Results : Serum ascorbic acid level was independently associated with high-den sity lipoprotein cholesterol (HDL-C) among women; each 1 mg/dl increas e in serum ascorbic acid level (range 0.1 to 2.7 mg/dl) was associated with a 2 mg/dl increase in HDL-C level (p=0.001). Because other inves tigators have demonstrated an inverse relation between ascorbic acid i ntake or blood levels and total serum cholesterol in individuals with elevated total serum cholesterol levels, we analyzed four subgroups of NHANES II participants with total serum cholesterol levels >200 mg/dl . Among women with total serum cholesterol levels greater than or equa l to 200 mg/dl, each 1 mg/dl increase in serum ascorbic acid level was independently associated with an increase of 2 to 3 mg/dl in HDL-C le vel (p less than or equal to 0.05). Serum ascorbic acid level was not significantly associated with other serum lipids or lipoproteins. Conc lusions: If the observed associations are linked causally, they would suggest that ascorbic acid is a factor in cholesterol homeostasis amon g women and may be particularly important for women at increased risk for coronary heart disease.