Skip Navigation LinksHome > June 2010 - Volume 58 - Issue 5 > Exchanging Carbohydrate or Protein for Fat Improves Lipid-Re...
Journal of Investigative Medicine:
doi: 10.231/JIM.0b013e3181da4d37
Original Articles

Exchanging Carbohydrate or Protein for Fat Improves Lipid-Related Cardiovascular Risk Profile in Overweight Men and Women When Consumed Ad Libitum

Kratz, Mario PhD*†; Weigle, David S. MD†; Breen, Patricia A. BSc, RN†; Meeuws, Kaatje E. BSc‡; Burden, Verna R. MS, RD‡; Callahan, Holly S. MSc, RD§; Matthys, Colleen C. BSc, RD§; Purnell, Jonathan Q. MD‡

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Abstract

Background: The impact of low-fat diets on the plasma lipoprotein profile is incompletely understood.

Methods: We conducted two 16-week dietary studies to compare the effects of a moderate-fat (mod-FAT) baseline diet with isocaloric and ad libitum low-fat diets rich in either carbohydrates (high-CHO, n = 16) or protein (high-PRO, n = 19) on plasma lipids, post-heparin lipase activities, cholesteryl ester transfer protein, and phospholipid transfer protein.

Results: Switching from the mod-FAT to the isocaloric high-CHO diet lowered plasma high-density lipoprotein cholesterol concentrations (P < 0.001) and tended to increase triglyceride levels (P = 0.087). Cholesterol content in the larger, buoyant low-density lipoprotein (LDL) fractions decreased, whereas those of the very-low-density lipoprotein, intermediate-density lipoprotein, and smaller, denser LDL fractions tended to increase. These changes were largely reversed when subjects lost weight by consuming this high-CHO diet ad libitum. Switching from the mod-FAT diet to the isocaloric high-PRO diet did not increase cholesterol content in the small-dense LDL fraction and led to decreases in both LDL and high-density lipoprotein cholesterol in plasma (P < 0.001 for both).

Consumption of the high-protein ad libitum diet accompanied by weight loss did not change plasma lipids further, except for a shift of cholesterol from dense low-density lipoprotein fractions to more buoyant low-density lipoprotein fractions. Cholesteryl ester transfer protein concentrations decreased with high-cholesterol feeding, whereas cholesteryl ester transfer protein concentrations and hepatic lipase and phospholipid transfer protein activities all decreased during high-protein feeding.

Conclusions: Both high-CHO and high-PRO diets improve plasma lipid-related risk of cardiovascular disease when consumed ad libitum.

© 2010 American Federation for Medical Research

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