Research on Fats, Oils and Other Lipids
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.
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