Effects of medium chain length triglyceride (MCT) on serum lipids and lipoproteins in familial hyperchylomicronemia (dietary fat-induced lipemia) and dietary carbohydrate-accentuated lipemia.

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Abstract Three siblings with familial hyperchylomicronemia (dietary fat-induced lipemia) and two subjects with "carbohydrate-accentuated" lipemia were studied during periods of strictly controlled diets. Corn oil, coconut oil, mixed, naturally occurring dietary fats, and medium chain triglycerides (MCT) consisting of 98 per cent C 8 and C 10 fatty acids, were fed in amounts contributing 40 per cent to 70 per cent of calories. In the siblings with hyperchylomicronemia (due to prolonged retention, of chylomicrons in the blood beacuse of a defective lipoprotein lipase system), marked reduction in serum triglyceride levels occurred when MCT was the sole source of dietary fat. Simultaneously with the reduction in serum triglyceride levels, there was an increase, both relative and absolute, in the amount of very low-density lipid (d f 20 to 400 lipoproteins rather than as chylomicron (S f > 5,000) lipid. When a fat-free diet was provided two of the siblings with hyperchylomicronemia, serum triglyceride levels were as low as, or lower than, those observed when MCT was the sole source of fat. The data provide additional evidence that the hyperglyceridemia in these subjects is due to excessive chylomicronemia, and that C 8 and C 10 fatty acids are not utilized for chylomicron triglyceride synthesis in the intestine to any appreciable degree. The feeding of formula diets containing MCT as the sole source of fat to the subjects with dietary carbohydrate—accentuated lipemia did not lower serum triglyceride levels, in comparison with corn oil or coconut oil. Lower serum triglyceride levels were observed when these subjects were fed diets in which 70 per cent rather than 40 per cent of the calories came from fat, regardless of the nature of the fat. MCT appeared less effective than corn oil or coconut oil in this respect. Serum cholesterol levels varied with triglyceride levels and were lowest when the sole source of dictary fat was corn oil.