Food Lipids: Chemistry, Nutrition, and Biotechnology

diet did. No effects were observed on plasma HDL cholesterol or triacylglycerol
concentrations. Using mixed natural diets, however, Temme et al. have found that
lauric acid raised total cholesterol concentrations more than palmitic acid, which was
partly due to an increase in HDL cholesterol [11] (Fig. 3).
The effects of myristic acid have been examined in several studies with mixed
solid foods. Zock et al. [12] concluded that myristic acid increased plasma total
cholesterol concentrations relative to palmitic and oleic acids, which was due to an
increase in both LDL and HDL cholesterol concentrations. However, triacylglycerol
concentrations were not affected (Fig. 4). Tholstrup et al. [13] also found that myristic
acid increased HDL cholesterol concentrations compared with palmitic acid.
However, no differences were observed in plasma LDL cholesterol concentrations.
c. Palmitic Acid. Replacing palmitic acid in the diet for carbohydrates lowers
LDL and HDL cholesterol concentrations. However, if the intake of palmitic acid is
decreased at the expense of oleic acid, LDL cholesterol concentrations decrease,
whereas HDL cholesterol is not affected [10–12] (Figs. 2–5). Recently, it has been
postulated that in normolipidemic, nonobese subjects palmitic acid may not always
be a cholesterol-raising saturated fatty acid [14,15], provided that linoleic acid intake
contributes at least 6–7% of daily energy intake and daily dietary cholesterol intake
is less than 300 mg. Of course, these findings will be of great practical significance
if it proves to be correct that under certain conditions palmitic acid can be exchanged
for oleic acid without affecting LDL cholesterol levels. However, these studies
[14,15] await confirmation.
d. Stearic Acid. Keys and coworkers already demonstrated that stearic acid did
not increase plasma total cholesterol concentrations [5,16]. However, the effects of
stearic acid on the distribution of cholesterol over the various lipoproteins were
Figure 3 Effects of lauric and palmitic acids on plasma total, LDL cholesterol, HDL cholesterol,
and triacylglycerol concentrations relative to those of cis-monounsaturated fatty acids
(oleic acid). Eighteen women and 14 men received three mixed natural diets, each for 6
weeks, in random order. The composition of the diets was identical, except for 8.5% of daily
energy intake, which was provided as lauric acid (C12:0), palmitic acid (C16:0), or oleic acid
(cis-C18:1) [11].
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