Blood sphingomyelins from two European countries

The objectives of this study were to isolate and analyse human blood sphingomyelins from two European populations which have significant differences in both the composition of dietary fat source and the rate of mortality from coronary heart disease. Blood samples have been taken from healthy adult volunteers from a Greek (Thessaloniki) and a French (Paris) region. The sphingomyelin fraction from red blood cells and plasma, separately, have been isolated by thin-layer chromatography and analysed by mass spectrometry after soft chemical ionisation with gas ammonia. The conditions used gave spectra with three discrete areas which correspond to ions coming from sphingoid bases, fatty acids and ceramides. Eight sphingoid bases have been detected in both red blood cells and plasma. Sphingosine was the major contributor. The rest of the sphingoid bases have 16 to 19 carbon atoms and 0 to 2 double bonds. Fourteen fatty acids, the same for red blood cells and plasma, have been detected with 16 to 26 carbon atoms and 0 to 2 double bonds. Palmitic acid was the most abundant fatty acid. Thirty eight ceramides have been detected in red blood cells and forty in plasma. Thirty six ceramides were common in red blood cells and plasma. Statistically significant differences (P < 0.01) have been detected between the two populations for some sphingoid bases, fatty acids and ceramides. Differences have also been found between the two populations in the degree of saturation of these sphingomyelin parts. These differences are attributed to (a) high monounsaturated fat, olive oil, consumption by Greeks and (b) other environmental and genetic factors. It is suggested that the detected differences between the two populations contribute to the different coronary heart disease rates observed among Greeks and French.