HEALTH BENEFIT OF
MONOUNSATURATED FATS: FOOD-BASED RESEARCH ON MUFAs
Penny Kris-Etherton
Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA
Significant progress has been made to reduce the incidence of
cardiovascular disease (CVD) in the U.S. However, CVD remains the
leading cause of death, accounting for more deaths than the other
leading causes of death collectively. Thus, there is still a pressing
need to develop effective intervention strategies to further reduce CVD
morbidity and mortality markedly. Diet remains a cornerstone in
prevention and treatment efforts. It is without question that lowering
dietary saturated fatty acids (SFA), trans fatty acids and cholesterol
are essential to lower LDL cholesterol levels, a major CVD risk
factor. There is a growing literature that indicates that
monounsaturated fatty acids (MUFA) have beneficial effects (when
substituted for SFA) on other CVD risk factors beyond lowering LDL
cholesterol levels. Compared with a low fat diet, a moderate fat diet
low in SFA and high in MUFA decreases triglyceride (TG) levels and
attenuates the HDL cholesterol, and in particular, the HDL(2)
decrease. A blood cholesterol-lowering diet high in MUFA favorably
affects hemostatic factors, including fibrinogen and coagulation
factors VIIc, XIIc, XIIa, and Xc. There is evidence that MUFA diets
also significantly improve insulin sensitivity compared with a high SFA
diet, providing that total fat does not exceed 37-38% of calories. A
limited body of evidence indicates that MUFA reduces blood pressure.
There also is emerging evidence that following a MUFA diet lowers
chylomicron remnant particle response to a high fat meal. Finally,
there is exciting evidence that a calorie restricted, moderate fat diet
high in MUFA favorably affects weight loss and maintenance of reduced
body weight compared with a low fat diet. Despite the numerous
beneficial effects of MUFA on multiple risk factors for CVD, there is
some evidence of potentially adverse effects. In monkeys fed a high
MUFA atherogenic diet for five years, coronary artery atherosclerosis
was comparable to that of monkeys fed an atherogenic diet high SFA;
atherosclerosis was minimal in animals fed a similar diet high in
polyunsaturated fatty acids. In addition, in human studies a high MUFA
fat load decreases flow mediated dilation (FMD) in the brachial
artery. However, this response is markedly attenuated when
antioxidants are included in the fat load. In summary, a diet that
emphasizes MUFA has many attributes that could reduce CVD mortality
especially within the context of a diet that has other cardioprotective
nutrients/components. Because of the worrisome monkey data, however,
an intervention study assessing atherosclerosis in humans is needed to
conclusively resolve the role of MUFA in a cardioprotective diet.
Nonetheless, even without these data, MUFA can be included in
moderation in a heart healthy diet that is rich in many
cardioprotective nutrients. This position is consistent with our
current thinking that there are many diverse diets that can be designed
to prevent CVD.
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