Complementary Alternative Cardiovascular Medicine

76 Alternative Cardiovascular Medicine
amount of dietary cholesterol. The original equations developed by Keys
et al. (5) and Hegsted et al. (6), reported by both in 1965, and more
recently by Mensink and Katan (7), Hegsted et al. (8), and Clarke et al.
(9), demonstrated that saturated fat was hypercholesterolemic, whereas
PUFA lowered blood cholesterol levels. Saturated fat was twice as potent
in raising blood cholesterol levels as PUFA was in lowering them. Specifically,
the blood cholesterol predictive equations demonstrated that for
each 1% increase in saturated fatty acids (SFAs), blood cholesterol
increased 1.5 to 2.7 mg/dL. The investigators reported that MUFA had
a neutral effect and that dietary cholesterol raised the blood cholesterol
level but less so than saturated fat. A summary of the effect of SFA on
LDL cholesterol is shown in Fig. 1.
TRANS FATTY ACIDS
Trans fatty acids are unsaturated fatty acids with one or more double
bonds in the trans configuration. The resulting extended fatty acid chain
is similar to saturated fat. Several epidemiologic studies have reported
a positive relationship between trans fatty acid intake and both incidence
of CHD and risk factors for CHD, notably lipids and lipoproteins (10–12).
Numerous early controlled feeding studies reported that hydrogenated
fats elicited a blood cholesterol response that was intermediate to
that observed for unhydrogenated oils and saturated fats (reviewed in
ref. 13). More recently, studies have been conducted to evaluate the
plasma lipid and lipoprotein effects of trans fatty acids. These studies
have consistently shown that trans fatty acids increase plasma total and
LDL cholesterol relative to unsaturated fatty acids (14–16). Trans fatty
acids elicit comparable cholesterol-raising effects vs SFA. In addition,
trans fatty acids do not increase high-density lipoprotein (HDL) cholesterol
as does SFA (17), resulting in a lower HDL cholesterol and a
worsening of the LDL:HDL ratio which, in turn, increases CHD risk (see
Fig. 2) (18).
DIETARY CHOLESTEROL
Numerous controlled clinical studies have shown a positive linear association
between dietary cholesterol and LDL cholesterol. Consequently,
because of an increase in LDL cholesterol, there is an increase in CHD risk.
However, the LDL cholesterol-raising effect of dietary cholesterol is less
than that of SFA. An increase of 100 mg/d of dietary cholesterol is predicted
to result in a 0.5 to 1 mmol/L increase in total serum cholesterol,
resulting in a 1% to 2% increase in CHD risk (see Fig. 3) (1).