Relation between dairy food intake and plasma lipid levels: The CARDIA study

Our research group previously reported that higher intake of dairy food is associated with lower incidence of obesity and insulin resistance syndrome, but did not study dairy foods in relation to plasma lipid levels. CARDIA is a longitudinal cohort study of 2,778 black and white men and women initially 18-30 years old. Diet was assessed at years 0 and 7 by an extensive diet history and plasma lipids were also measured. Multiple regression analysis was used to examine concurrent change in plasma lipid levels and change in dairy food intake. LDL-C increased by 3 mg/dL across quintiles of seven-year change in total high fat dairy intake (p=0.04). After correction for within-person error in dietary assessment, the true mean increase in LDL-C from lowest to highest quintile of change in dairy food intake was estimated to be 3-6 times larger, about 10-18 mg/dL. Neither change in HDL-C nor TG was associated with change in dairy food intake among consumers, but consumers of low-fat milk had lower HDL-C (change was about 1 mg/dL less than the HDL-C change in non-consumers, p=0.04), while the HDL-C was higher among consumers of butter and cream (p=0.02). Among consumers of total low-fat dairy food and of yogurt, TG was lower among consumers (change in TG was 6-7 mg/dL lower than that of non-consumers, p=0.05 and 0.002, respectively). Young adults who increased high fat dairy food consumption had higher LDL-cholesterol, in part balanced by higher HDL-cholesterol. The implications for health of consumption of dairy food require additional research.