Dietary Trans Fatty Acids Increase Small, Dense LDL Particles

Laurie Barclay, MD

September 02, 2003

Sept. 2, 2003 — Consumption of dietary trans fatty acids (FAs) is associated with a deleterious increase in small, dense low-density lipoprotein (LDL) cholesterol particles, according to the results of a study published in the September issue of the American Journal of Clinical Nutrition. This finding further reinforces the importance of promoting diets low in trans FAs to improve the lipoprotein profile.

"Dietary trans FAs, which are formed during the process of hydrogenating vegetable oil, are known to increase plasma LDL-cholesterol concentrations," write Jean-François Mauger, from Laval University in Quebec, Canada, and colleagues. "Accumulating evidence indicates that the size of LDL particles confers an independent risk, with small and dense particles being more atherogenic than are larger, less dense particles."

In this study, 18 women and 18 men each consumed five different experimental diets in random order for 35-day periods. In each diet, fat accounted for 30% of total energy intake. However, the diets differed in fat composition, with two thirds of the fat in the form of semiliquid margarine (0.6 g trans FAs/100 g fat), soft margarine (9.4 g trans FAs/100 g fat), shortening (13.6 g trans FAs/100 g fat), stick margarine (26.1 g trans FAs/100 g fat), or butter, which was low in trans FAs (2.6 g trans FAs/100 g fat) but rich in saturated fat. Polyacrylamide gradient gel electrophoresis identified LDL particle size and distribution.

With increasing amounts of dietary trans FAs, LDL particle size decreased significantly and in a dose-dependent fashion compared with LDL particle size seen with the butter-enriched diet ( P < .001). Cholesterol concentration in large (>260 Å) and medium (255–260 Å) size LDL particles also increased proportionately to the amount of trans FAs in the diet.

"Interestingly, compared with the four diets enriched in trans fatty acids, the diet enriched with saturated fat (butter) was associated with the highest plasma LDL-cholesterol concentrations but, paradoxically, the largest LDL particles," the authors write. "These data reinforce the importance of promoting diets that are low in saturated fat and that contain a minimal quantity of trans fatty acids from hydrogenated fat in order to favorably affect the lipoprotein profile and thus contribute to a reduced risk of cardiovascular disease."

The authors report no potential conflicts of interest in this study.

Am J Clin Nutr. 2003;78(3):370-375

Reviewed by Brunilda Nazario, MD

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