Exogenous fatty acids (essential fatty acids, EFA – essential fatty acid) also called essential fatty acids, a group of fatty acids that can not be synthesized in the animal body, including humans, and must be supplied in food, in opposed to endogenous acids. Feeding poor nutrients with essential fatty acids can lead to sickness disorders.

Types
Among the unsaturated fatty acids, a group of polyunsaturated fatty acids is distinguished, which contain more than one carbon-carbon double bond in the hydrocarbon chain of the acid residue. They are an essential element of the human diet (they constitute a group of the so-called vitamin F), because they are needed to create important compounds, eg prostaglandins. The most important essential fatty acids in humans are:
• linoleic acid
• α-linolenic acid
From these fatty acids, the human body can synthesize other fatty acids it needs. EFAs under the name of vitamin F (international name: vitaminum F) is used in medicine. Indications for use are, among others skin diseases.

The effects of scarcity
Deficiency in EFA:
• may cause skin diseases (dandruff)
• increases water loss in the body
• during pregnancy, it may lead to underdevelopment of the fetus

Occurrence
They occur mainly in the fats of aquatic animals and vegetable oils.

Polyunsaturated acids:
• linoleic (LA) – safflower, corn, sunflower, soybean, peanut, rapeseed oil, olive oil
• α-linolenic acid (ALA) – linseed oil, rapeseed oil, walnut oil
• γ-linolenic (GLA) – borage oil [2], evening primrose, black currant, hemp
• arachidonic (AA) – animal products, meat
• eicosapentaenoic (EPA) – algae, salmon, fish oil (cod)
• docosahexaenoic acid (DHA) – mackerel oil, some algae, flax seeds