Continuedfrom Last Issue
By SallyFallon and Mary G. Enig, PhD
Says Wolke: "I found noresearch studies indicating that today’s low-erucic-acid canola oil,as distinguished from ordinary rapeseed oil, is harmful to humans."That’s because, even though canola oil now has Generally Recognizedas Safe (GRAS) status, no long-term studies on humans have been done.
Animal studies on Low ErucicAcid Rapeseed oil were performed when the oil was first developed andhave continued to the present. The results challenge not only the healthclaims made for canola oil, but also the theoretical underpinnings ofthe diet-heart hypothesis.
The first published studieson the new oil were performed in 1978 at the Unilever research facilityin the Netherlands.11 The industry was naturally interested to know whetherthe new LEAR oil caused heart lesions in test animals. In earlier studies,animals fed high-erucic-acid rape seed oil showed growth retardation andundesirable changes in various organs, especially the heart, a discoverythat touched off the so-called "erucic acid crisis" and spurredplant geneticists to develop new versions of the seed.
The results of the LEAR studywere mixed. Rats genetically selected to be prone to heart lesions developedmore lesions on the LEAR oil and the flax oil, than those on olive oilor sunflower oil, leading researchers to speculate that the omega-3 fattyacids (not erucic acid) in LEAR and flax oil might be the culprit. Butrats genetically selected to be resistant to heart lesions showed no significantdifference between the four oils tested and LEAR oil did not cause heartproblems in mice, in contrast to high-erucic oil which induced severecardiac necrosis.
In 1979, researchers at theCanadian Institute for Food Science and Technology pooled the resultsof 23 experiments involving rats at four independent laboratories. Alllooked at the effects of LEAR and other oils on the incidence of heartlesions. They found that saturated fats (palmitic and stearic acids) wereprotective against heart lesions but that high levels of omega-3 fattyacids correlated with high levels of lesions. They found a lesser correlationwith heart lesions and erucic acid.12
In 1982, the same researchgroup published a paper that looked at the interaction of saturated fatswith LEAR oil and soybean oil. When saturated fats in the form of cocoabutter were added to the diets, the rats in both groups had better growthand a significant lowering of heart lesions. Said the authors: "Theseresults support the hypothesis that myocardial lesions in male rats arerelated to the balance of dietary fatty acids and not to cardiotoxic contaminantsin the oils."13
Canadian researchers lookedat LEAR oils again in 1997. They found that piglets fed milk replacementcontaining canola oil showed signs of vitamin E deficiency, even thoughthe milk replacement contained adequate amounts of vitamin E.14 Pigletsfed soybean oil-based milk replacement fortified with the same amountof vitamin E did not show an increased requirement for vitamin E. VitaminE protects cell membranes against free radical damage and is vital toa healthy cardiovascular system.
In a 1998 paper, the same researchgroup reported that piglets fed canola oil suffered from a decrease inplatelet count and an increase in platelet size.15 Bleeding time was longerin piglets fed both canola oil and rapeseed oil. These changes were mitigatedby the addition of saturated fatty acids from either cocoa butter or coconutoil to the piglets’ diet. These results were confirmed in anotherstudy a year later. Canola oil was found to suppress the normal developmentalincrease in platelet count.16
Finally, studies carried outat the Health Research and Toxicology Research Divisions in Ottawa, Canadadiscovered that rats bred to have high blood pressure and proneness tostroke had shortened life-spans when fed canola oil as the sole sourceof fat.17 The results of a later study suggested that the culprit wasthe sterol compounds in the oil, which "make the cell membrane morerigid" and contribute to the shortened life-span of the animals.18
These studies all point inthe same direction -- that canola oil is definitely not healthy for thecardiovascular system. Like rapeseed oil, its predecessor, canola oilis associated with fibrotic lesions of the heart. It also causes vitaminE deficiency, undesirable changes in the blood platelets and shortenedlife-span in stroke-prone rats when it was the only oil in the animals’diet. Furthermore, it seems to retard growth, which is why the FDA doesnot allow the use of canola oil in infant formula.19
When saturated fats are addedto the diet, the undesirable effects of canola oil are mitigated. Mostinteresting of all is the fact that many studies show that the problemswith canola oil are not related to the content of erucic acid, but morewith the high levels of omega-3 fatty acids and low levels of saturatedfats.
RapeseedOil In Traditional Diets
Rapeseed oil has been usedin China, Japan and India for thousands of years. In areas where thereis a selenium deficiency, use of rapeseed oil has been associated witha high incidence of fibrotic lesions of the heart, called Keshan’sdisease.20 The animal studies carried out over the past twenty years suggestthat when rapeseed oil is used in impoverished human diets, without adequatelysaturated fats from ghee, coconut oil or lard, then the deleterious effectsare magnified.
In the context of healthy traditionaldiets that include saturated fats, rapeseed oil, and in particular erucicacid in rapeseed oil, does not pose a problem. In fact, erucic acid ishelpful in the treatment of the wasting disease adrenoleukodystrophy andwas the magic ingredient in Lorenzo’s oil.
High levels of omega-3 fattyacids, present in unprocessed rapeseed oil, don’t pose a problemeither when the diet is high in saturates. A 1998 study indicates thatdiets with adequate saturated fats help the body convert omega-3 fattyacids into the long-chain versions EPA and DHA, which is what the bodywants to do with most of the 18-carbon omega-3s.21
Conversion is reduced by 40-50percent in diets lacking in saturated fats and high in omega-6 fatty acidsfrom commercial vegetable oils (particularly soybean oil). In the animalstudies on canola oil, dietary saturated fats mitigated the harmful effectsof omega-3s.
A 1995 Wall Street Journalarticle reported that use of rapeseed oil in cooking was associated withgreatly increased rates of lung cancer in the women breathing the fumes.22Once again, a lack of saturates in the diet may explain the association,because the lungs can’t work without adequate saturated fats.23 InIndia, rapeseed oil has been used as a cooking oil for thousands of years,but only recently have Indian housewives been cajoled into the beliefthat saturated butter and ghee should be avoided. Many now use vanispati,an imitation ghee made of partially hydrogenated soybean oil.
Rapeseed has been used as asource of oil since ancient times because it is easily extracted fromthe seed. Interestingly, the seeds were first cooked before the oil isextracted. In China and India, rapeseed oil was provided by thousandsof peddlers operating small stone presses that press out the oil at lowtemperatures. What the merchant then sells to the housewife is absolutelyfresh.
Modern oil processing is adifferent thing entirely. The oil is removed by a combination of hightemperature mechanical pressing and solvent extraction. Traces of thesolvent (usually hexane) remain in the oil, even after considerable refining.Like all modern vegetable oils, canola oil goes through the process ofcaustic refining, bleaching and degumming -- all of which involve hightemperatures or chemicals of questionable safety.
And because canola oil is highin omega-3 fatty acids, which easily become rancid and foul-smelling whensubjected to oxygen and high temperatures, it must be deodorized. Thestandard deodorization process removes a large portion of the omega-3fatty acids by turning them into trans fatty acids. Although the Canadiangovernment lists the trans content of canola at a minimal 0.2 percent,research at the University of Florida at Gainesville, found trans levelsas high as 4.6 percent in commercial liquid oil.24 The consumer has noclue about the presence of trans fatty acids in canola oil because theyare not listed on the label.
A large portion of canola oilused in processed food has been hardened through the hydrogenation process,which introduces levels of trans fatty acids into the final product ashigh as 40 percent.25 In fact, canola oil hydrogenates beautifully, betterthan corn oil or soybean oil, because modern hydrogenation methods hydrogenateomega-3 fatty acids preferentially and canola oil is very high in omega-3s.Higher levels of trans mean longer shelf life for processed foods, a crispertexture in cookies and crackers -- and more dangers of chronic diseasefor the consumer.26
TheMyth Of Monounsaturates
Consumer acceptance of canolaoil represents one in a series of victories for the food processing industry,which has as its goal the replacement of all traditional foods with imitationfoods made out of products derived from corn, wheat, soybeans and oilseeds. Canola oil came to the rescue when the promotion of polyunsaturatedcorn and soybean oils had become more and more untenable. Scientists couldendorse canola oil in good conscience because it was a "heart-healthy"oil, low in saturated fat, high in monounsaturates and a good source ofomega-3 fatty acids.
But most of the omega-3s incanola oil are transformed into trans fats during the deodorization process;and research continues to prove that the saturates are necessary and highlyprotective.
At least it can be said thatcanola oil is a good source of monounsaturated fat -- like olive oil --and therefore not harmful. . . Or is it? Obviously monounsaturated fattyacids are not harmful in moderate amounts in the context of a traditionaldiet, but what about in the context of the modern diet, where the health-consciouscommunity is relying on monounsaturated fats almost exclusively?
There are indications thatmonounsaturated fats in excess and as the major type of fat can be a problem.Overabundance of oleic acid (the type of monounsaturated fatty acid inolive and canola oil) creates imbalances on the cellular level that caninhibit prostaglandin production.27 In one study, higher monounsaturatedfat consumption was associated with an increased risk of breast cancer.28
Even the dogma that monounsaturatedfatty acids are good for the heart is at risk. According to a 1998 report,mice fed a diet containing monounsaturated fats were more likely to developatherosclerosis than mice fed a diet containing saturated fat.29 In fact,the mice fed monounsaturated fats were even more prone to heart diseasethan those fed polyunsaturated fatty acids.
This means that the type ofdiet recommended in books like The Omega Diet -- low in protective saturates,bolstered with high levels of omega-3 fatty acids and relying on monounsaturatedfatty acids, whether from olive or canola oil, for the majority of fatcalories -- may actually contribute to heart disease. Such diets havebeen presented with great marketing finesse, but we need to recognizethem for what they are -- payola for the food companies and con-ola forthe public.
TheGreat Con-ola was published in Nexus Magazine, Aug/September 2002as well as in Wise Traditions, the quarterly publication for the WestonA. Price Foundation. To receive a free 12-page brochure containingMyths and Truths about Nutrition and concise Dietary Guidelines, contactthe Foundation at (202) 333-HEAL or email@example.com.
Sally Fallonis President of the Weston A. Price Foundation and author of NourishingTraditions: The Cookbook that Challenges Politically Correct Nutritionand the Diet Dictocrats, NewTrends Publishing, 2000 (877-707-1776,newtrendspublishing.com)
Mary G.Enig, PhD, FACN, is Vice President of the Weston A. Price Foundation,President of the Maryland Nutritionists Association and author of KnowYour Fats: The Complete Primer for Understanding the Nutrition of Fats,Oils and Cholesterol, Bethesda Press, 2000 (301-680-8600, bethesdapress.com)
11. ROVles and others. Nutritional Evaluation of Low-Erucic-Acid RapeseedOils. Toxicological Aspects of Food Safety, Archives of Toxicology,Supplement 1, 1978:23-32
12. HLTrenholm and others. An Evaluation of the Relationship of Deitary FattyAcids to Incidence of Myocardial Lesions in Male Rats. Canadian Instituteof Food Science Technology Journal, October 1979;12(4):189-193
13. JKGKramer and others. Reduction of Myocardial Necrosis in Male Albino Ratsby Manipulation of Dietary Fatty Acid Levels. Lipids, 1982;17(5):372-382.
14. FDSauer and others. Additional vitamin E required in milk replacer dietsthat contain canola oil. Nutrition Research, 1997;17(2):259-269.
15. JKKramer and others. Hematological and lipid changes in newborn pigletsfed milk-replacer diets containing erucic acid. Lipids, January 1998;33(1):1-10.
16. SMIunis and RA Dyer. Dietary canola oil alters hematological indices andblood lipids in neonatal piglets fed formula. Journal of Nutrition,July 1999;129(7):1261-8.
17. WMNRatnayake and others. Influence of Sources of Dietary Oils on the LifeSpan of Stroke-Prone Spontaneously Hypertensive Rats. Lipids, 2000;35(4):409-420.
18. MNWallsundera and others. Vegetable Oils High in Phytosterols Make ErythrocytesLess Deformable and Shorten the Life Span of Stroke-Prone SpontaneouslyHypertensive Rats. Journal of the American Society for Nutritional Sciences,May, 2000;130(5):1166-78
19. FederalRegister, 1985.
20. OALevander and MA Beck. Selenium and viral virulence. British MedicalBulletin, 1999;55(3):528-33.
21. H Gerster.Can adults adequately convert alpha-linolenic acid (18:3n-3) to eicosapentaenoicacid (20:5n-3) and docosahexaenoic acid (22:6n-3)? International Journalof Vitamin and Nutrition Research 1998;68(3):159-73.
22. WallStreet Journal, June 7, 1995, p. B6.
23. MGEnig. Benefits of Saturated Fats. Wise Traditions, Summer 2000;1(2):49.
24. S O'Keefeand others. Levels of Trans Geometrical Isomers of Essential Fatty Acidsin Some Unhydrogenated US Vegetable Oils. Journal of Food Lipids 1994;1:165-176.
25. JLSebedio and WW Christie, eds. Trans Fatty Acids in Human Nutrition,The Oily Press, Dundee, Scotland, 1998, pp 49-50.
26. MGEnig, Trans Fatty Acids in the Food Supply: A Comprehensive Report Covering60 Years of Research, 2nd Edition, Enig Associates, Inc., Silver Spring,MD, 1995.
27. Horrobin,David F, Prostaglandins: Physiology, Pharmacology and Clinical SignificanceThe Book Press, Brattleboro, Vermont, 1978, p 20, 35
28. V Palaand others. Erythrocyte membrane fatty acids and subsequent breast cancer:a prospective Italian study. Journal of the National Cancer Institute,July 18, 2001;93(14):1088-95.
29. LLRudel and others. Dietary monounsaturated fatty acids promote aorticatherosclerosis in LDL-receptor-null, human ApoB100-overexpressing transgenicmice. Arteriosclerosis, Thrombosis and Vascular Biology, November 1998;18(11):1818-27.