Polyunsaturated fatty acids are the structural elements of mitochondrial membrane. Mitochondrial membrane loses its activity when there is deficiency of EFA, which may cause swelling and reduction of oxidative phosphorylation.

Fats with a high content of polyunsaturated fatty acids lower the serum cholesterol level.

Inadequate EFA may lead to a fatty liver.

Docosahexaenoic acid (22:6n-3) is the common polyenoic acid present in the retinal photoreceptor membrane. It is formed from linolenic acid. Docosahexaenoic acid is responsible for the electrical response of the photoreceptors to illumination. Hence, linolenic acid is essential in the diet for optical vision.

Biomediacl importance of EFA:

1. Human deficiency of some cases are eczma like dermatitis,
2. Degenerative changes in arterial wall and
3. Fatty liver in man may be due to EFA deficiency.
4. There are also some reports that administration of EFA in such cases may produce:
5. Some improvement of eczema in children kept on skimmed milk.
   1. Prevent fatty liver and
   2. Lowering of cholesterol level.
   3. Infant and babies with low fat diet may develop typical skin lesions which has shown to be improved in EFA.