Dietary restriction of saturated fat and cholesterol decreases HDL ApoA-I secretion.
We examined the mechanisms responsible for the decrease in HDL cholesterol (HDL-C) levels after the consumption of a diet low in total fat, saturated fat, and cholesterol. Twenty-one subjects with a mean age of 58+/-12 years were placed on a baseline isocaloric diet (15% protein, 49% carbohydrate, 36% fat, and 150 mg/1000 kcals of cholesterol) and then switched to an NCEP Step 2 diet (15% protein, 60% carbohydrate, 25% fat, and 45 mg/1000 kcals of cholesterol). After 6 or 24 weeks on each diet, subjects received a 15-hour primed-constant infusion of [5,5,5-2H3]-L-leucine. HDL apoA-I and apoA-II tracer curves were determined by gas chromatography-mass spectrometry and fitted to a monoexponential equation. Compared with the baseline diet, consumption of the Step 2 diet lowered HDL-C mean levels by 15% (1.03+/-0.23 to 0.88+/-0.16 mmol/L, P<0.001), apoA-I by 12% (1.25+/-0.15 to 1.10+/-0.13 g/L, P<0. 001) and the TC/HDL-C ratio by 5% (0.145+/-0.04 to 0.137+/-0.03). No significant changes were observed in apoA-II levels and HDL particle size with diet. HDL apoA-I fractional catabolic rate did not change (0.219+/-0.052 to 0.220+/-0.043 pools/day, P=0.91) but HDL apoA-I secretion rate decreased by 8% (12.26+/-3.07 to 10.84+/-2.11 mg. kg-1. day-1, P=0.03) during consumption of the Step 2 diet. There was no effect of diet on apoA-II fractional catabolic rate or secretion rate. Our results indicate that the decrease in HDL-C and apoA-I levels during the isocaloric consumption of a Step 2 diet paralleled the reductions in apoA-I secretion rate.
Vélez-Carrasco
W
W
Lipid Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, USA.
Lichtenstein
A H
AH
Welty
F K
FK
Li
Z
Z
Lamon-Fava
S
S
Dolnikowski
G G
GG
Schaefer
E J
EJ
D000328:Adult; D000368:Aged; D016632:Apolipoprotein A-I / Q000097:blood / Q000378:metabolism*; D016633:Apolipoprotein A-II / Q000378:metabolism; D002791:Cholesterol, Dietary / Q000008:administration & dosage*; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D015243:Cholesterol, VLDL / Q000097:blood; D018752:Diet, Fat-Restricted; D005260:Female; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood* / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood
D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; D002791:Cholesterol, Dietary; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D015243:Cholesterol, VLDL; D008075:Lipoproteins, HDL; D014280:Triglycerides