Nutritive Value and Safety of Hydrogenated Vegetable Fats as Evaluated by Long-Term Feeding Experiments with Rats

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Abstract
A multigeneration study in which rats have been fed a ration containing 9.24% of a selectively hydrogenated vegetable oil as practically the sole source of fat in the diet has now been carried through 46 generations. The performances of rats of generations 26 through 46 as judged by gain in weight, tibia length, reproduction, lactation, longevity and carcass analyses have shown that the hydrogenated fats are of full nutritional value. The presence of 6.9% essential fatty acids (expressed as linoleic acid) in the hydrogenated vegetable fat has been shown to be sufficient to maintain normal plasma and liver cholesterol levels and liver lipid levels in the rat. The test animals in the multigeneration studies ingested per unit of body weight about 10 times as much trans-fatty acid isomers as would be ingested by the human on a diet with all the visible fat in the form of the selectively hydrogenated vegetable oils. In the case of the longevity studies, this ratio was as high as 30:1. Hydrogenation of margarine fats does not produce excessive saturated fatty acids and indeed the essential fatty acid content of the hydrogenated margarine oil can be relatively high. Attention has been directed to the relatively saturated fat deposited in the body of animals on low fat diets, even those containing limpid vegetable oils rich in essential fatty acid content. Previous experiments on generations one through 25 of this multigeneration study have yielded beneficial results on metabolism studies, digestibility studies and histopathological examination of the tissues in addition to the nutritional indices mentioned above. In other studies, the fatty acid isomers contained in the hydrogenated fats exhibited no measurable antimetabolite activity toward the essential fatty acids despite an average of about 7:1 in the ratio of trans-isomers to biologically active fatty acid content. It is therefore concluded that selectively hydrogenated vegetable oils, such as are employed in margarine manufacture, containing positional and stereoisomers of the unsaturated fatty acids, are fully digestible, harmless, and of full nutritional value as determined by long-term studies conducted with rats. In all the multigeneration and longevity studies, herein reported, no deleterious effects were observed as a result of the ingestion of the small amounts of saturated fatty acids present in the hydrogenated fats.