Two essential fatty acids

Jan 2014   Two essential fatty acids
Essential fatty acids (EFAs) are essential because human body cannot synthesize them.
Fatty acids (FAs) are required for energy production and also for carrying out many important biochemical functions. Most of the required FAs are synthesized by our body. Alpha-linolenic acid (ALA) and linoleic acid (LA) are the two essential fatty acids which our body cannot synthesize.
This inability of our biochemical system necessitates inclusion of these two FAs in our diet. Diet lacking these FAs can cause
deficiency diseases of fats and increase the risk of cancer, atherosclerosis, chronic inflammation and coronary arteriosclerosis.

Biochemical functions

There many mutually mediated biochemical interactions of these two EFAs. Eicosanoids are signalling molecules formed from EFAs. There are four classes of eicosanoids and those derived from ARA are inflammatory whereas those derived from EPA may be less inflammatory, or inactive, or even anti-inflammatory. Further the same eicosanoid can be pro-inflammatory or anti-inflammatory depending upon the target tissue. For the conversion into their derivatives, ALA and LA compete for the same enzymes and the greater presence of LA in the diet promotes pro-inflammatory cascades. EFAs are also modified to form endocannabinoids having neurological functions.

Conditionally essential

ALA is a precursor of two important FAs namely docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). LA is a precursor of arachidonic acid (ARA), another biochemically important FA connected with inflammatory process.

When the diet lacks ALA, deficiency of DHA and EPA will arise. The lack of LA in the diet causes the deficiency of ARA. If there is malabsorption or malnutrition due to diseases or developmental conditions, again the body can become deficient. There is another situation wherein the conversion of the precursors may be affected due deficiency in the required conversion enzymes or impairment in the enzyme production itself. In all these circumstances DHA, EPA or ARA become conditionally essential fatty acids and have to be included in the diet or supplemented to avoid their nutritional deficiency diseases.

Vegetable oils, fish, marine algae, linseed, walnuts, fish oil, krill oil, milk, dairy products and meat products are good sources of these two essential FAs.

1. Related topics on nutritional deficiency diseases:
Diseases of vitamin deficiency.
Diseases of carbohydrate deficiency.
Protein energy malnutrition.
Diseases of protein deficiency.
Diseases of mineral deficiency.
Examples of monounsaturated fatty acids.

Present topic on nutritional deficiency diseases:
Two essential fatty acids.

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