Serum lipids, dietary factors and ischemic heart disease

Abstract

Serum lipid levels in 28 pairs of age-matched railwaymen from two geographically different population groups with disparate consumption of fats and showing big differences in mortality rates from ischemic heart disease showed no significant differences in total and ester cholesterol, free and esterified fatty acids, and total serum triglycerides. Although the consumption of fats, most of which were of animal origin, was 10 times more in North Indians as compared with South Indians, there were no differences in the levels of their serum lipids. These differences in diet were, on the other hand, related inversely to the fecal and urine urobilinogen excretion, which may indicate that in the presence of a deficiency of bilirubin in the intestinal lumen less fat is absorbed even though more may be present in the food, while in the case of a higher bilirubin content more fat is absorbed even though less was present in the food. The role of physical activity, smoking, and the amount and kind of fat in these results is unproved. These results can be explained entirely on the basis of the amount of bilirubin available in the intestine, which in turn seems to depend upon the pattern of diet and eating. Evidence pertaining to the possible differences in the chain length of plasma triglyceride acids, despite there being no differences in the serum lipid levels in our two groups, is discussed and this may explain the discrepancy that mortality from ischemic heart disease is 15 times higher among our South Indian population as compared with our North Indian population. This is true even though the South Indians eat one-tenth as much fat, most of which is from seed oils and is composed of long-chain fatty acids, in contrast to the North Indians whose dietary fats are mostly of animal origin but have a preponderance of short-chain fatty acid triglycerides.