Ba. Clevidence et al., PLASMA-LIPOPROTEIN (A) LEVELS IN MEN AND WOMEN CONSUMING DIETS ENRICHED IN SATURATED, CIS-MONOUNSATURATED, OR TRANS-MONOUNSATURATED FATTY-ACIDS, Arteriosclerosis, thrombosis, and vascular biology, 17(9), 1997, pp. 1657-1661
Studies that have shown adverse effects of transunsaturated fatty acid
s on plasma lipoprotein (a) [Lp(a)] levels have used levels of trans-f
atty acid that are higher than those in the average U.S. diet. This st
udy was conducted to clarify the effects on Lp(a) of trans-fatty acids
levels commonly found in U.S. diets. Lp(a) levels were measured in a
double-blind study of 29 men and 29 women who ate 4 controlled diets i
n random order for 6 weeks each. Fatty acids represented 39% to 40% of
energy. The diets were: (1) Oleic (16.7% of energy as oleic acid); (2
) Moderate trans (3.8% of energy as trans-monoenes, approximately the
trans content of the U.S. diet); (3) High trans (6.6% of energy as tra
ns-monoenes); (4) Saturated (16.2% of energy as lauric plus myristic p
lus palmitic acids). The Saturated diet lowered Lp(a) levels significa
ntly (by 8% to 11%). Compared to the Oleic diet, the trans diets had n
o adverse effect on Lp(a) levels when all subjects were considered col
lectively. A subset with initially high levels of Lp(a) (greater than
or equal to 30 mg/dL), however, responded to the High trans diet with
a slight (5%) increase in Lp(a) levels relative to the Oleic and Moder
ate trans diets. Thus, in amounts commonly found in the typical U.S. d
iet, saturated fatty acids consistently decrease Lp(a) concentrations.
The adverse effects of replacing cis-with trans-fatty acids are only
suggestive and are restricted to high trans intakes in subjects with h
igh Lp(a) levels.