No adverse effects seen from transpolyunsaturated acids.

The predominant unsaturated fatty acids, which come mostly from vegetable and fish oils in our dietary fats, are the cis fatty acids. A fatty acid molecule is a cis molecule when its hydrogen atoms are located in a normal position in its spatial arrangement. When this normal spatial arrangement becomes altered, the molecule becomes a trans molecule. Although this difference in the structure of a molecule appears minor, it has a great impact on the way the fatty acid functions in the body.

In recent years, trans fatty acids have caused concern among nutritionists because of their possible role in promoting heart diseases. We obtain dietary trans fatty acids mainly from foods that include industrially processed fats. The chemical hardening process, hydrogenation, is the process that yields most of the trans fatty acids. The foods that contain relatively high amounts of these compounds include margarines and biscuits.

Many published scientific studies have covered transmonounsaturated fatty acids, mainly because they have been easier to analyze than the transpolyunsaturated acids. However, polyunsaturated fatty acids are essential components of our biological systems since they are the building blocks of tissue membranes.

European scientists have investigated the metabolism of transpolyunsaturated fatty acids to determine their effects on the risk factors for coronary heart disease in humans. Scientists from France, the United Kingdom and the Netherlands have reported their results from a dietary intervention trial carried out with 88 European healthy male volunteers subjected to either low- or high-transpolyunsaturated diets.

During the six-week trial, a relatively high intake of polyunsaturated trans-alpha-linolenic acid supplied in oil, margarine, cheese, muffins and biscuits did not increase the risk of coronary heart disease by promoting platelet aggregation and blood coagulation. Another study by French and U.K. scientists with ten healthy male volunteers concluded that transpolyunsaturated fatty acids are used for energy production in humans at least as well as their cis counterparts.

Further information. J.L. Sebedio, Institut Nationale de la Recherche Agronomique, Unite de Nutrition Lipidique, Rue Sully, 17, FR-21034 Dijon Cedex, France; phone: [phone]; fax: [phone]; email: [e-mail].