Complementary Alternative Cardiovascular Medicine

Chapter 6 / Oils, Fats, and CVD 79
decrease and HDL cholesterol levels are maintained. In contrast, a lowfat,
high-carbohydrate, cholesterol-lowering diet increases triglycerides
and lowers HDL cholesterol (19). Thus, a diet moderate in total fat from
MUFA and low in SFA calories results in a more favorable CHD risk
profile than does a low-fat diet. Both diets would be expected to lower
total and LDL cholesterol similarly, however, a moderate-fat, high-
MUFA diet elicits a more favorable LDL cholesterol/HDL cholesterol
ratio, as well as plasma triglyceride level. The advice to consume a
moderate-fat diet with emphasis on MUFA must be done so in the context
of keeping SFA low, because all fats carry SFA and ensure that
energy balance is maintained, because all fats are energy dense.
The message that unsaturated fats can be part of a healthy diet must
be translated sensibly to prevent overconsumption. For example, some
populations living in the Mediterranean region safely consume diets
containing greater than 20% energy from MUFA. However, there is,
some preliminary and limited evidence that excessive MUFA intake
may be problematic. One study showed that flow-mediated dilation (an
indicator of vascular health) decreased in human subjects in response to
a 50-g fat load from olive oil compared with canola oil (20). Interestingly,
this response was attenuated when antioxidants were included in
the fat load. Balsamic vinegar also had the same effect. Another study
has shown that MUFAs induce atherosclerosis in monkeys fed an atherogenic
diet (21). These are isolated reports of adverse effects of MUFA
on CVD risk status that should be further studied. In contrast, there is
convincing evidence that MUFAs have important health effects in the
context of current dietary guidance.
POLYUNSATURATED FATTY ACIDS
PUFAs are mainly comprised of omega-6 and omega-3 fatty acids.
The distinction between the two fatty acid classes is made on the basis
of the position of the first double bond from the CH 3 terminus (yielding
the designations omega-6 or omega-3). PUFAs contribute approx 7% of
total energy intake from fat in the diet of adults in the United States (22).
Linoleic acid (18:2n-6) is the major PUFA, comprising 84–89% of the
total PUFA energy, whereas ALA (18:3n-3) contributes 9–11% of the
total PUFA energy in the diet of the adult population. Intake of n-3 fatty
acids is approx 1.6 g/d (approx 0.7% of energy), of which 1.4 g is ALA
and 0.1–0.2 g is EPA (20:5) and DHA (22:6).
Omega-6 Fatty Acids
Prospective epidemiologic studies have reported an inverse association
between linoleic acid intake and risk of coronary death (23,24). In