Alpha-linolenic acid deficiency in patients on long-term gastric-tube feeding: estimation of linolenic acid and long-chain unsaturated n-3 fatty acid requirement in man

Alpha-linolenic acid deficiency is described in four adults fed by gastric tube. In plasmaand erythrocytes,total lipid 20:3n-9 was slightly increased but total n-6 fatty acids, arachidonic acid, and dihomo-gammalinolenic acid were normal. Total n-3 fatty acids, l8:3n-3, 20:5n-3, 22:5n-3, and 22:6n-3 were decreased in both plasma and erythrocytes. Patients had a slight but definite scaly dermatitis, which disappearedwith essential fatty acids supplementation.Simultaneously, levelsof 18:3n-3, 20:5n-3, 22:5n-3, 22:6n-3, 20:3n-9, and total n-3 fatty acids became normal while l8:2n-6, 20:3n-6, 20:4n-6, and total n-6 acidswere unchangedor slightly lowered.Estimated minimal daily requirement of linolenic acid and of long-chain unsaturated n-3 acidsin adults is �0.2-0.3% and 0.1-0.2%, respectively,of total energyintake. Resultssuggestthat conversionof linolenic acid to 22:6n-3 is increasedin linolenic acid deficiency. Am I Clin Nuir l987;45:66-77.