Criteria for essential fatty acid deficiency in plasma as assessed by capillary column gas-liquid chromatography.

To develop criteria for deficiency of essential fatty acids (EFA), we used capillary-column gas-liquid chromatography to determine fatty acids (percentage of total fatty acids) in plasma obtained in the fasting state from 56 reference subjects and from 10 patients with intestinal fat malabsorption and suspected EFA deficiency. Fatty acid evaluations (percentage of total fatty acids) that allowed for a clear distinction (P less than 0.01) between reference subjects and patients, based on values two standard deviations below or above the reference mean, included values for linoleic acid (18:2w6) below 27%, and values for palmitic acid (16:0), palmitoleic acid (16:1w7), oleic acid (18:1w9), vaccenic acid (18:1w7), and Mead acid (20:3w9) exceeding 21%, 2.6%, 23.3%, 2.1%, and 0.21%, respectively. Ratios of total EFA to total non-EFA of less than 0.60 and of Mead acid to arachidonic acid of greater than 0.025 also served to identify patients, and were not found in reference subjects. Significant inverse correlations between percentages of plasma EFA and plasma mono-unsaturated fatty acids were noted. Our reference-interval data can be used to assess normality of plasma EFA status.