Arachidonic acid

Arachidonic acid (lat. arachis = "peanut") is an unsaturated C20 fatty acid that is synthesized by most animal organisms (exception: cats), but not by plants. Depending on the diet, it is absorbed in abundance through food.

In membranes of animal cells, arachidonic acid occurs in esterified (physiologically inactive) form as a component of lipids, e.g. phospholipids.

Arachidonic acid is the most important fatty acid for prostaglandin and leukotriene synthesis. As a component of a triglyceride, it is firmly integrated into the cell membrane. Arachidonic acid is released from the cell membranes by the enzyme phospholipase A2 in response to appropriate stimuli.

The cytosolic, free arachidonic acid thus becomes biologically active and forms the starting point for the enzymatic synthesis of:

• prostaglandins and
• leukotrienes

Cytochrome P450 is also able to oxidize arachidonic acid.

Arachidonic acid in food:

The arachidonic acid content is particularly high in lard (1700 mg per 100 g), pork liver (870 mg per 100 g), egg yolk (297 mg per 100 g), tuna (280 mg per 100 g), liver sausage (230 mg per 100 g).

Other foods / Arachidonic acid content:

• Cow's milk, 1.5 % fat: 2 mg / 100 g
• Cow's milk, 3.5 % fat: 4 mg / 100 g
• Buttermilk, 1 % fat: 1 mg / 100 g
• Condensed milk, 7.5 % fat: 8 mg / 100 g
• Sour cream, 10 % fat: 11 mg / 100 g
• Whipped cream, 30 % fat: 32 mg / 100 g
• Yoghurt, 1.5 % fat: 2 mg / 100 g
• Yoghurt, 3.5 % fat: 4 mg / 100 g
• Cheeses:
  • Camembert, 30 % fat in dry matter 13 mg / 100 g
  • Camembert, 60 % fat in dry matter 34 mg / 100 g
  • Emmental, 45 % fat in dry matter 28 mg / 100 g

The values given are guidelines and are subject to natural fluctuations. (Source: O. Adam, Diät und Rat bei Rheuma und Osteoporose, Walter Hädecke Verlag)

The metabolites of arachidonic acid (they are called eicosanoids, from the Greek είκοσι = twenty) act as broadly active signaling molecules and are of particular importance for inflammatory processes in the body. The activity of the enzyme fatty acid cyclooxygenase produces prostaglandins (PG) and thromboxanes (TX) from arachidonic acid. The activity of lipoxygenases produces hydroperoxyderivatives and hydroxyderivatives. The 5-lipoxygenase is responsible for the formation of leukotrienes (LT).

A high nutritive intake of arachidonic acid is suspected to promote inflammatory diseases, e.g. of the rheumatic form. The arachidonic acid itself seems to activate inflammatory processes in a variety of ways.

In v. Kupffer's star cells, arachidonic acid activates TNF-alpha production in animal experiments. It is also increased in cell systems of animals that have been pretreated with ethyl alcohol.

Low levels of arachidonic acid apparently have a negative influence on the cognitive abilities of an elderly person. An arachidone-enriched diet can improve these deficiencies (Tokuda H et al. (2014).

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