Mono-unsaturated fats like olive oil may benefit the heart not only by lowering cholesterol but also by reducing blood pressure and blood sugar, a study in Italy has suggested.
The study, being published today in The Journal of the American Medical Association, supports earlier indications that mono-unsaturated fats might have multiple health benefits. For example, a study in Dallas two years ago showed improvement in blood glucose levels in people with diabetes when the diet was rich in monounsaturated fats.
The Dallas researchers, headed by Dr. Scott Grundy of the University of Texas Health Science Center, demonstrated in experiments that fats like olive oil were at least as effective as polyunsaturated oils in lowering blood cholesterol. Their research indicated that unlike polyunsaturated oils, the mono-unsaturates lowered only the harmful low-density lipoprotein (LDL) cholesterol, not the beneficial high-density lipoprotein (HDL) cholesterol.
The finding prompted many Americans to switch to olive oil and canola oil, also high in mono-unsaturates, as their primary oils for cooking and use in salads. Before this report, heart-conscious Americans focused on polyunsaturated vegetable oils, like those derived from corn, sunflower and safflower seeds, and soybeans, which help reduce blood cholesterol.
The new Italian study surveyed the diets and other relevant habits of 4,903 men and women 20 to 59 years old who lived in nine communities. Wide differences in the types of fats used in the various communities in Italy allowed the researchers to determine whether fat intake influenced risk factors for heart disease independently of other known influences like cigarette smoking and obesity.
Olive Oil as a Positive Factor
The findings showed that those who consumed the most olive oil had the lowest levels of blood cholesterol, blood pressure and blood glucose. In addition, diets high in polyunsaturated fats were associated with low blood levels of cholesterol and glucose, but not necessarily lower blood pressure.
On the other hand, those who ate butter tended to have higher levels of blood cholesterol, blood pressure and blood glucose. About half the men and women who participated in the study reported that they never used butter, a rich source of saturated fat, which has long been known to raise cholesterol levels.
The researchers, led by Dr. Maurizio Trevisan of the State University of New York School of Medicine in Buffalo, warned against drawing firm conclusions from their findings, noting that dietary factors other than fats that were not directly measured might explain some of the findings.
They also noted that the biological mechanisms to explain the effects of mono-unsaturated fats on blood cholesterol, blood pressure and blood sugar remained to be explained.
High Level of Saturated Fats
In the same issue of the journal, the American Medical Association's Council on Scientific Affairs said that Americans consume almost twice the maximum amount of saturated fats recommended to reduce the risk of heart disease.
The main sources of saturated fats in the American diet are animal products - dairy, meat and poultry primarily -and the oils, coconut, palm kernel and palm, which are used in many processed foods.
The council said it supported efforts to improve food labeling to alert consumers to the types and amounts of fats in the foods they purchase.
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