FROM: Nutr Res 1993: 13 (1) Suppl: S19–S45
Dietary lipid interventions have an important role in modulating
the onset of autoimmunity, cardiovascular diseases and cancer.
Many studies carried out in the past have established the adverse
effects of saturated fats in humans and in animal models. Based
on these adverse effects, the consumption of vegetable oils
containing both monounsaturated omega (omega)-9 and
polyunsaturated fatty acids (rich in 18:2 omega-6) is rising
significantly in the United States. The increased consumption of
many vegetable oils particularly of omega-6 series is however to
be viewed as pro-inflammatory and its suspected as one of the
possible causes for the gradual rise in certain malignant tumors,
rheumatoid arthritis and autoimmune diseases primarily due to the
increased production of pro-inflammatory cytokines although its
increased usage has reduced cardiovascular disease nearly 30% in
the United States. Diets based on omega-6 enriched oils can
increase the level of linoleic acid in tissue phosphoglycerides
and are able to reduce cholesterol levels, yet these lipids
usually tend to elevate excessive arachidonic acid (20:4 omega-
6) levels. In contrast, omega-3 fatty acid-enriched fish oil (FO)
and/or omega-3 precursors from certain vegetable oils (linolenic
acid, 18:3 omega-3) are found to provide protection against
cardiovascular disease, rheumatoid arthritis, cancer and possibly
against the severity of viral infections. Nutritional
modification of cellular functions by dietary lipids with a
balanced ratio of omega-6 and omega-3 fatty acids offers an
attractive avenue to correct, modify and/or prevent many
patho-physiological processes in health and disease state and to
reduce toxicity of drugs in many patients. The mediation of such
effects is thought to be primarily achieved through alterations
of cellular membranes composition and other endogenous lipid
stores which may modify the functional activity of various
receptors on plasma membranes. In summary, the protective effects
of omega-3 lipids have been explained based on changes in
eicosanoid synthesis and the reduced risk of sudden death from
cardiac arrhythmia, increased protection from ischemic
myocardium, improved myocardial function and reduction of other
cardiovascular and autoimmune disease risks. However,
well-designed studies are still required to further define the
key role of both combination of omega-6 and omega-3 fatty acids,
from marine and vegetable sources, both as a supplement to infant
nutrition specifically for optimizing the development of
cognitive function, and also as preventive measure for reducing
the incidence of diseases of aging in rapidly growing elderly
populations.