Changes in serum triglycerides and high-density lipoprotein concentration and composition after a low-fat mixed meal. Effects of gender and insulin resistance

Postprandial lipaemia is generally studied after a test meal that provides most of the calories as fat and that does not reflect the common food intake. We investigated postprandial changes in serum triglycerides (TG) and in high-density lipoprotein (HDL) concentration and composition after a regular meal poor in fat (30% of calories). Fifty-four women and 54 men had breakfast at 8:00 a.m. (12% of daily calories) and lunch at 12:30 p.m. (53% of daily calories). With respect to fasting values, TG increased more in men (24% at 2:30 p.m. and 30% at 5:00 p.m.) than in women (19% and 23%, respectively). HDL cholesterol decreased by 4% both in men and women at 2:30 p.m., and in both genders levels returned towards baseline levels at 5:00 p.m. Apolipoprotein A-I (apo A-I) significantly decreased in men (-3% at 2:30 p.m.), but did not change in women. The apo A-I/HDL cholesterol ratio significantly increased by 3% in men at 2:30 p.m. and by 5% both in men and women at 5:00 p.m. Postprandial serum TG were higher and HDL cholesterol and apo A-I were lower in subjects of both genders with insulin resistance (high HOMA_IR) than in those with low HOMA_IR. The greatest increase in serum TG (39%) was observed in men with high HOMA_IR. HDL cholesterol and apo A-I significantly decreased and the apo A-I/HDL-C ratio significantly increased only in this subgroup of subjects. Ingestion of low doses of fat in a mixed meal is followed by variable increases of serum TG, and the greatest response is found in insulin-resistant men. In this subset of subjects, postprandial hypertriglyceridaemia is associated with alterations in HDL that might be consistent with an increased risk of cardiovascular disease.