A Study of Blood Clotting and Serum Lipids in Natives of New Guinea and Australians

Summary Male natives of New Guinea, aged 20 to 40 years, whose dietary fat intake provided 18% of their caloric needs, were found to be shorter, more muscular and less obese than Australians of the same age, but their weight relative to height was the same. The natives had lower serum levels of cholesterol, phospholipids and alpha and beta lipoproteins (paper electrophoresis and cholesterol elution), and a higher phospholipid‐cholesterol ratio. There was evidence that the phospholipid‐cholesterol ratios of the alpha and beta lipoproteins were quite different from those in Europeans. Any increase in the total serum cholesterol content of Australians was borne solely by the beta lipoproteins, the alpha fraction remaining constant at about 44 milligrammes per 100 millilitres ; but in natives the cholesterol at all levels was shared between the alpha (17%) and beta fractions (83%). Whole blood clotting times in siliconed tubes and "Stypven" clotting times were significantly longer in the Australians than in the natives. Alpha lipoprotein appeared to inhibit and beta lipoprotein possibly accelerated clotting in the "Stypven" test. Obesity in Australians was not related to changes in blood clotting, but was associated with a decreased alpha lipoprotein, an increased beta lipoprotein and a consequent fall in the serum phospholipid‐cholesterol ratio. While no relationship between obesity and serum lipids was demonstrated in natives, increasing fatness was associated with a shortening of the "Stypven" clotting time. The results are discussed especially in regard to the thrombogenic and lipid theories of atherogenesis.