The Minnesota omnivore control group of 100 adults had an w3/w6 ratio of 0.13, about half the optimum ratio calculated for rats, and about one-third of the high ratio found in Nigerians. At the time of these studies, the use of partially hydrogenated fats had not significantly influenced the EFA status of the Nigerians, whereas American supplies of food fats and oils had turned toward partially hydrogenated oils in which 18:3w3 was preferentially converted to monounsaturated fatty acids, increasing shelf life of the products. The essentiality of w3 fatty acids for humans was demonstrated in 1982 (6), but this had little effect upon the trend toward increased use of partially hydrogenated oils. Fortunately, use of effective antioxidants have permitted the entry of unhydrogenated soybean oil and Canola oil to the market in recent years, and both of these are good sources of w3 EFA.
The American taste for foods fried in deep fat increases their intake of partially hydrogenated fats which are rich in isomers of oleic acid and which inhibit the metabolism of linoleic and linolenic acids to their longer chain metabolic products, as does natural oleic acid (4). Our tastes for saturated fats and high levels of sugar in the diet, also tend to lower our consumption of sources of linolenic acid, and to enhance the deposit of saturated fat in our fatty tissues.
What can we do to improve the national status with respect to w3 EFA? I can protest that w3 polyunsaturated fatty acids are at least as essential for tissue structure and function as are the w6 EFA. We already have a good supply of w3-rich soybean and Canola oils. It is a gold mine. The food oil industry should market these as w3 oils rather than partially destroying them by hydrogenation. Corn oil, cottonseed oil, safflower oil and sunflower oils are now our most abundant, but dominantly w6 "polyunsaturated oils". Molecular biologists should find and insert genes for w3 synthesis into strains of these species, creating more balanced, truly polyunsaturated vegetable oils. The nutritional and medical communities should wake up to the essentiality and necessity of w3 EFA in the diets of humans. They should recognize that cholesterol is not the problem, but an indicator. Restoring balanced w3 and w6 polyunsaturation IS the problem!
Until these things happen, we as individuals can watch what we eat. Use Canola oil as a spread and in frying, rather than butter and margarine. Use ground flax, rich in 18:3w3 in cooking and baking. Eat fish and lean meat which are rich in long-chain w3 and w6 acids. Eat less of foods loaded with sugar and saturated fats. Generally avoid deep-fat fried foods. By these means one can lower plasma cholesterol and improve one's w3 fatty acid status.
- Phinney, S. D., Odin, R.S. Johnson, S.B. and Holman, R.T. Reduced Arachidonate in Serum Phospholipids and Cholesteryl Esters associated with Vegetarian Diets in Humans. Am. J. Clin. Nutr. 51, 385-392 (1990).
- R.T. Holman. A Long Scaly Tale - The Study of Essential Fatty Acid Deficiency at the University of Minnesota. In "Essential Fatty Acids and Eicosanoids" (Andrew Sinclair and Robert Gibson, Eds.) American Oil Chemists' Society, Champaign, IL, pp. 3-17 (1993).
- Ralph T. Holman, S.B. Johnson, D. M. Bibus, T.C. Okeahialem and Peter O. Egwim. High Omega 3 EFA Status in Nigerians and Low Status in Minnesotans.WWW J. Biol .
1, 2nd issue paper 3, (Nov. 1,1996)
- Ralph T. Holman. Nutritional and Metabolic Interrelationships Between Fatty Acids. Fed. Proc. 23, 1062-1067 (1964).
- Yehuda, S. and Carosso, R.L. Modulation of Learning, Pain Thresholds and Thermoregulation in the Rat by Preparations of Free Purified alpha-Linolenic and Linoleic acids. Determination of the Optimal w3/w6 Ratio. Proc. Natl. Acad. Sci. USA 90: 10345-10349 (1993)
- Ralph T. Holman, Susan B. Johnson and Terry F. Hatch. A Case of Human Linolenic Acid Deficiency Involving Neurological Abnormalities. Am. J. Clin. Nutr. 35, 617-623 (1982).
Ralph T. Holman, Senior Editor
Emeritus Professor of Biochemistry,
Univ. of Minnesota
Former Director, The Hormel Institute,
Univ. of Minnesota
Adjunct Professor of Biochemistry,
Mayo Medical School
Member, National Academy of Sciences, USA