Replacement of carbohydrate by protein in a conventional-fat diet reduces cholesterol and triglyceride concentrations in healthy normolipidemic subjects.
OBJECTIVE
To determine the effect on plasma lipid profiles of replacement of dietary carbohydrate by low-fat, high-protein foods.


METHODS
Cross-over randomized controlled trial.


METHODS
Ten healthy, normolipidemic subjects (8 women and 2 men).


METHODS
Subjects were randomly allocated to either a low-protein (12%) or high-protein (22%) weight-maintaining diet for 4 weeks and then switched to the alternate diet for 4 more weeks. The first 2 weeks of each diet served as an adjustment/washout period. Fat was maintained at 35% of energy, mean cholesterol intake at 230 mg per day and mean fibre intake at 24 g per day. Compliance was promoted by the use of written dietary protocols based on the food preferences of the subjects and weekly dietary consultation as required.


METHODS
Mean plasma levels of total, very-low-density-lipoprotein (VLDL), low-density-lipoprotein (LDL), and high-density-lipoprotein (HDL) cholesterol, and of total and very-low-density-lipoprotein (VLDL) triglycerides. Satiety levels were self-rated on a 10-point scale.


RESULTS
Consumption of the high- versus the low-protein diet resulted in significant reductions in mean plasma levels of total cholesterol (3.8 v. 4.1 mmol/L, p < 0.05), VLDL cholesterol (0.20 v. 0.26 mmol/L, p < 0.02), LDL cholesterol (2.4 v. 2.6 mmol/L, p < 0.05), total triglycerides (0.69 v. 0.95 mmol/L, p < 0.005) and VLDL triglycerides (0.35 v. 0.57 mmol/L, p < 0.001), as well as in the ratio of total cholesterol to HDL cholesterol (3.1 v. 3.5, p < 0.01). A trend towards an increase in HDL cholesterol (1.26 v. 1.21 mmol/L, p = 0.30) was observed but was not statistically significant. Satiety levels tended to be higher among those eating the high-protein diet (6.1 v. 5.4, p = 0.073).


CONCLUSIONS
Moderate replacement of dietary carbohydrate with low-fat, high-protein foods in a diet containing a conventional level of fat significantly improved plasma lipoprotein cardiovascular risk profiles in healthy normolipidemic subjects.
Wolfe
B M
BM
Department of Medicine, University of Western Ontario, London. bernard.wolfe@lhsc.on.ca
Piché
L A
LA
D000328:Adult; D001835:Body Weight / Q000502:physiology; D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL / Q000097:blood; D018592:Cross-Over Studies; D004032:Diet; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D005260:Female; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D012528:Satiety Response / Q000502:physiology; D014280:Triglycerides / Q000097:blood*
D008076:Cholesterol, HDL; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D014280:Triglycerides; C030106:very low density lipoprotein triglyceride; D002784:Cholesterol