Decrease of polyunsaturated fatty acids and elevation of the oleic/stearic acid ratio in plasma and red blood cell...

The fatty acids profiles of plasma and red blood cell lipids have been evaluated in 12 malnourished cancer patients in comparison with samples from eight healthy controls. In such patients, significantly lower levels of linoleic acid (LA) as percentage of total fatty acids were observed in plasma phospholipids (PL) and cholesterol esters (CE), and in red blood cells PL. The levels of arachidonic acid (AA) and the unsaturation index of the two lipid classes were also reduced in plasma CE but not in PL. In spite of the marked reduction of LA and, more generally, of total polyunsaturated fatty acids (PUFA), no elevation of eicosatrienoic acid (20:3 n-9) was observed, such acid being considered a typical index of essential fatty deficiency. Moreover, no modification of the parameters indicating impairment of the fatty acid desaturation activity was shown. In addition, the levels of palmitic and oleic acids were significantly higher in both plasma PL and CE and in red blood cells PL. The reported elevation of the oleic to stearic acid ratio in lipids of red blood cells from malnourished cancer patients, already observed by other authors, was confirmed in our study. This ratio was even more markedly elevated in plasma lipids of the patients. A very good correlation was found between the reduction of linoleic acid levels, especially in plasma CE, and weight loss, suggesting enhanced utilization of this fatty acid in association with extensive depletion of lipid stores, in this pathological state.