Arachidonic acid

Arachidonic acid (lat. arachis = "peanut") is an unsaturated C20 fatty acid that is synthesized by most animal organisms (except cats), but not by plants. It is abundantly absorbed in the diet, depending on the dietary pattern.

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. It is firmly integrated into the cell membrane as a component of a triglyceride. 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.

Furthermore, cytochrome P450 is able to oxidize arachidonic acid.

Arachidonic acid in food:

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

The values given are indicative and subject to variation. Source: O. Adam, Diet and advice for rheumatism and osteoporosis, Walter Hädecke Verlag.

The metabolites of arachidonic acid (they are called eicosanoids "from Greek eicosi = twenty") act as broadly effective signal molecules and are of particular importance for inflammatory processes in the body. Through the activity of the enzyme fatty acid cyclooxygenase, arachidonic acid is converted into prostaglandins (PG) and thromboxanes (TX). The activity of lipoxygenases produces hydroperoxide derivatives and hydroxide derivatives. 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).

1. Chauhan S et al (2015) Dual inhibition of arachidonic acid pathway by mulberry leaf extract. Inflammopharmacology 23:65-70.
2. Crawford MA et al (2015) The European Food Safety Authority recommendation for polyunsaturated fatty acid composition of infant formula overrules breast milk, puts infants at risk, and should be revised. Prostaglandins Leukot Essent Fatty Acids 103:1-3.
3. Cubero FJ et al (2012) Arachidonic acid stimulates TNFα production in Kupffercells via a reactive oxygen species-pERK1/2-Egr1-dependent mechanism. At J Physiol Gastrointest Liver Physiol 303:G228-239.
4. Cui YL et al (2015)Molecular basis of the recognition of arachidonic acid by cytochrome P450 2E1 along major access tunnel. Biopolymer 103:53-66.
5. Kozak W et al. (2000) Molecular mechanisms of fever and endogenous antipyresis. Ann N Y Acad Sci 917: 121-134
6. Laniado-Schwartzman M et al (2008) 20-hydroxyeicosatetraenoic acid stimulates nuclear factor-kappaB activation and the production of inflammatory cytokines in human endothelial cells. J Pharmacol Exp Ther 324: 103-110
7. Tokuda H et al (2014) Arachidonic acid-enriched triacylglycerol improves cognitive function in elderly with low serum levels of arachidonic acid. J Oleo Sci 63:219-227.