Trans fatty acid is produced mainly by hydrogenation of unsaturated fatty acid, a process which occurs during the production of margarine. The atherogenecity of trans fatty acid was tested using a fat in which 47.5% of the fatty acid was trans fatty acid.
Seven-day-old male chicks were fed an atherogenic regimen of either cholesterol, or trans fatty acid, or a combination of the two. Trans fat, which was liquified by hot water, was force-fed at a dose of 1ml per 100g of body weight. Cholesterol was mixed directly into the diet and fed at a rate of 0.7g per 100g of body weight. Only the cholesterol treatment caused significant changes, including moderate hyperlipidemia and a slight increase in lipid deposition in the thoracic aorta, especially in the fibroblast-like cells. The degeneration of smooth muscle cells was remarkable in the aortas from chicks fed trans fat. An additive increase in both serum total cholesterol and triglyceride levels was noted in chicks fed both cholesterol and trans fat. Moreover, many more foam cells were observed in this group, in addition to the degenerated smooth muscle cells, especially in the thickened intimal of the abdominal aorta.