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


METHODS
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).


RESULTS
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.


CONCLUSIONS
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.
Branchi
Adriana
A
Department of Internal Medicine, University of Milan, Fondazione IRCCS, Ospedale Maggiore Policlinico, Mangiagalli and Regina Elena, Milan, Italy. adriana.branchi@unimi.it
Torri
Adriana
A
Berra
Cristina
C
Colombo
Emanuela
E
Sommariva
Domenico
D
D000328:Adult; D000368:Aged; D016632:Apolipoprotein A-I / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D005260:Female; D005502:Food; D006801:Humans; D007333:Insulin Resistance; D008075:Lipoproteins, HDL / Q000097:blood*; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D012307:Risk Factors; D012737:Sex Factors; D014280:Triglycerides / Q000097:blood*
D016632:Apolipoprotein A-I; D008076:Cholesterol, HDL; D004041:Dietary Fats; D008075:Lipoproteins, HDL; D014280:Triglycerides