The role of dietary fats and oils in human nutrition is one of the most important areas of concern and investigation in the field of nutritional science. Dietary cholesterol and saturated fatty acids, particularly lauric, myristic and palmitic acids, have been implicated in the etiology of cardiovascular vascular disease by a large body of evidence from epidemiological, clinical and animal research. In recent years, concerns were raised about the health effects of trans fatty acids, which are very often present in large quantities in margarines, shortenings, fast foods and many common bakery products made from partially hydrogenated vegetable oils. The health effects of trans fatty acids are not resolved yet, but the concerns include adverse effects on lipid risk factors for heart disease and metabolism of n-6 and n-3 fatty acids (essential fatty acids). In contrast to the negative health effects associated with saturated and trans fatty acids, dietary fats in general have a number of nutritional functions. They serve as a concentrated source of energy and as a source of essential fatty acids. They act as carriers of fat-soluble vitamins and affect the palatability of foods. The n-6 and n-3 families of polyunsaturated fatty acids (also known as omega-6 and omega-3 fatty acids) are important components of cell membranes and serve as
precursors of a variety of biologically active compounds, known as eicosanoids. Since lack of these fatty acids leads to deficiency symptoms and they can only be obtained from the diet, they are essential dietary nutrients. Common vegetable oils such as canola and soybean oil are good sources of both linoleic (18:2n-6) and a-linolenic (18:3n-3) acids, which are the parent members of the n-6 and n-3 families of polyunsaturated fatty acids. The longest and highly unsaturated members of the n-3 series are present in substantial amounts in marine fish, whereas eggs and meat from land animals are a convenient source of the long-chain highly unsaturated members of the n-6 series. These polyunsaturated fatty acids are particularly required by human infants for normal growth and development, and also they play a crucial role in brain and visual function. Breast milk is a dependable source of both n-6 and n-3 fatty acids for infants.
New evidence concerning the benefits and risks associated with particular aspects of dietary fat is constantly evolving in both the scientific literature and the popular media. At times, controversies about these findings evolve. Determinations of nutritional effects of trans fatty acids and their levels in Canadian margarines, fast foods, bakery products and breast milk of lactating mothers are a major research activity of the lipid laboratory. Development of analytical methods for accurate measurement of trans fatty acids is another component of the trans fatty acid research of the lipid laboratory. In addition to these activities, at present studies are being conducted using a hypertensive rat model to determine the influence of vegetable oils, plant sterols, cholesterol and protein on the development of hypertension and haemorrhagic stroke. Other projects include a series of studies using animal models to determine the interactive effects of fat, protein and vitamin E on the lipid risk factors for cardiovascular disease. Data gathered from these activities will provide new information on the role that dietary fats play in health and disease.