Contrasting effects of low or high copper intake on rat tissue lipid essential fatty acid composition.

The effects of low copper intake or copper supplementation on the metabolism of stearic acid have been studied previously, but their effects on essential fatty acids have not been reported. Male Sprague-Dawley rats were fed for 12 weeks on pelleted semi-synthetic diets containing less than 1 mg/kg copper (low copper), 6 mg/kg (copper control), or 250 mg/kg copper (copper supplemented). The fatty acid composition of the total phopholipids and triglycerides of plasma, liver, heart and adipose tissue was analyzed by gas liquid chromatography. In low copper rats compared to controls, palmitic and oleic acids were decreased but stearic acid and docosahexaenoic acid were increased in plasma, liver and heart phopholipids. Arachidonic acid was also increased in plasma and liver phospholipids in low copper rats. In liver triglycerides, linoleic and arachidonic acids were increased but palmitic and oleic acid were decreased in low copper rats. Copper supplementation had the opposite effect; palmitic and oleic acids were increased in phospholipids and triglycerides whereas essential fatty acids were generally decreased. Hence, copper not only has a direct effect on the desaturation of stearic acid but also has significant effects on the tissue lipid composition of essential fatty acids.