Short-Term and Long-Term Pathological Effects of Glyceryl Trierucate and of Increasing Levels of Dietary Rapeseed Oil in Rats

Abstract

Diets containing rapeseed oil (RSO) or glyceryl trierucate (GTE), each supplying 25 cal% erucic acid, were compared for their effect on the cardiac morphology in male Wistar rats after 1 week, and on growth, pathology and heart and kidney weights after 24 weeks. Sunflowerseed oil (SSO) and a rapeseed oil supplying ca. 4 cal% erucic acid (LER) served as control fats. The RSO and GTE diets produced similar effects. After 1 week, cardiac lipidosis was observed in both dietary groups; after 24 weeks, lipidosis had decreased remarkably and cellular scars were the main pathological feature. The severity of the lipidosis and of the fibrotic changes was similar in both groups. Growth and the relative weights of the heart and kidneys were significantly different – mutually as well as in comparison with the control rats fed SSO. It was concluded that erucic acid is the main pathogenic fatty acid in RSO, but other long-chain fatty acids may also play a minor role. The animals fed LER showed normal growth and organ weights compared with the SSO group. Slight cardiac lipidosis was observed after 1 week. After 24 weeks, some animals showed cardiac cellular scars varying in intensity from slight to moderate. In a second experiment, Sprague-Dawley rats were fed 0, 5, 10, 15, 20, 25 or 30 cal% RSO in diets made isocaloric in fat by addition of SSO. The rats were killed after 3 and 6 days and 32 weeks. All rats fed RSO for 3 and 6 days showed a dose-related lipidosis of the heart. The groups fed RSO for 32 weeks showed myocardial changes which were already manifest in a few animals on the 5 cal% RSO diet. Incidence and severity of these changes increased according as the RSO content of the diet was increased.

Growth, Heart Weight, Cardiac Lipid, and Pathology of Chickens Fed Soybean Oil or Oil Extracted from Different Rapeseed Cultivars

“…Interestingly, the Chester Beatty (Hooded) rat, which also absorbs fat via the portal system, does not show evidence of myocardial damage when fed rapeseed oils (Hulan et al, 1977a). These results tend to support our previous hypothesis (Hulan et al, 1976) that erucic acid per se is not the sole causative agent of myocardial damage as postulated by Abdellatif and Vies (1973). The myocardial damage observed in the R-500 fed chickens in the current studies is likely related to the fatty acid imbalance of the oil coupled with its extremely high 22:1 content.…”

Low erucic acid canola oil does not induce heart triglyceride accumulation in neonatal pigs fed formula

“…These findings were not unexpected because several studies have noted trace to moderate lipidosis in rats and piglets fed oils without 22:1n-9 (1,7,8,16,20), and the neonate is known to have an immature capacity for fatty acid oxidation (28). The biochemical analysis did not find lower heart triglyceride concentrations in piglets fed the Canola mimic (which provided similar amounts of C 16 and C 18 fatty acids without 22:1n-9 or the sterols of canola oil) or the formula with soybean oil than in piglets fed the formulas with canola oil.…”

“…The maximal safe intake of 22:1n-9 that does not lead to lipidosis in rat heart has been estimated to be 2 to 10% dietary fatty acids (1)(2)(3)(4)(5)(6)(7)(8). The U.S. Food and Drug Administration currently permits dietary oils containing no more than 2% fatty acids as 22:1n-9 in foods for adults and children, but does not permit use of canola oils in infant formulas (9).…”

Pathological Changes Associated with the Feeding of Soybean Oil or Oil Extracted from Different Rapeseed Cultivars to Single Comb White Leghorn Cockerels

“…This led to the assumption by several workers that erucic acid alone was responsible for the production of the myocardial necrosis (Abdellatif and Vies, 1973;Engfeld and Brunius, 1975;Astorg and Cluzan, 1976). Subsequently, new varieties of rapeseed have been developed that yield oil low in erucic acid content.…”