Effects of biotin deficiency on plasma and tissue fatty acid composition: evidence for abnormalities in rats.

Abnormalities of fatty acid composition have been detected in the plasma of patients who developed frank biotin deficiency during parenteral nutrition. We sought to determine which abnormalities of fatty acid composition, if any, would be replicated in the biotin-deficient rat and to determine the relative temporal relationships of these abnormalities to biotin nutritional status. We measured fatty acid compositions of the phospholipids extracted from plasma, heart, and liver and assessed biotin nutritional status longitudinally in biotin-deficient and biotin-treated rats during progressive biotin deficiency. In the biotin-deficient group, significant increases relative to the biotin-treated group were detected in all three tissues in the odd-chain fatty acids 15:0 and 17:0. In the biotin-deficient rats, significant increases in 18:2 omega 6 in liver and 18:3 omega 6 in plasma and liver and significant decreases in 22:5 omega 6 were detected in plasma and liver. The constellation of fatty acid abnormalities observed in the biotin-deficient rats was not identical to that observed in biotin-deficient patients, but abnormalities in composition of odd-chain fatty acids were detected in both human and rat and therefore are attributable to biotin deficiency per se. The abnormalities in fatty acid composition were already present by wk 4 on the egg white diet; the cutaneous findings appeared between wk 3 and 6. These observations are consistent with the hypothesis that an abnormality in fatty acid metabolism may play a pathogenetic role in the cutaneous manifestations of biotin deficiency.