Nutritional value of micro-encapsulated fish oils in rats.

Abstract

The nutritional value of a micro-encapsulated fish oil product has been investigated. Three groups of 10 male Wistar rats each were fed diets containing 20% (w/w) of fat, and only the type and form of the fat added was different. In the test groups 5% (w/w) of fish oil either as such or in a micro-encapsulated form was incorporated in the diets. The remaining fat was lard supplemented with corn oil to a dietary content of linoleic acid at 10% (w/w). The control group received lard and corn oil only. A mixture similar to the dry matter in the micro-encapsulated product was also added to the diets not containing this product. The uptake of marine (n-3) polyunsaturated fatty acids (PUFA) from both types of fish oil supplement was reflected in the fatty acid profiles of liver phosphatidyl cholines (PC), phosphatidyl ethanolamines (PE), triglycerides (TG) and cardiolipin (CL). A suppression of the elongation of linoleic acid leading to a higher concentration of this fatty acid in liver PC and PE was also observed. The concentration of total lipids, triglycerides, cholesterol and phospholipids in liver was similar in all groups. Supplements of long chain (n-3) PUFA did not influence the concentration of plasma TG but lowered the level of plasma cholesterol. No change in the oxidative status, measured as glutathione peroxidase activity and cytochrome P450 concentration in the liver, was found after feeding with fish oil either directly or in the micro-encapsulated form. Intake of (n-3) PUFA lowered the concentration of vitamin E in plasma while the content of vitamin E in the liver was unchanged. Overall, fish oil and micro-encapsulated fish oil resulted in the same fatty acid pattern in the major lipid classes and the same concentrations of liver and plasma lipids. Furthermore, supplementation of fish oil or micro-encapsulated fish oil did not induce oxidative stress when the diets were supplemented with ambient concentrations of anti-oxidants. It is concluded that micro-encapsulated fish oil is suitable for increasing the intake of (n-3) PUFA by fortification of normal daily food ingredients.