Arachidonic acid (AA)

Arachidonic acid (AA) is a long-chain omega-6 fatty acid and the main precursor of pro-inflammatory eicosanoids (prostaglandin E2, leukotrienes, thromboxane A2). The AA/EPA ratio is looked at in the fatty acid profile in questions of inflammation. How your values are to be read is set out in your findings report. Measured directly in the omega-3/6 fatty acid analysis.

What arachidonic acid does in the body

Arachidonic acid (AA) has 20 carbon atoms and four double bonds. The body makes it from linoleic acid or takes it in directly with foods of animal origin. It sits in the phospholipids of cell membranes, particularly abundantly in immune cells, platelets, the vessel wall and the brain. In response to a stimulus – such as an injury or a signal from a pathogen – the enzyme phospholipase A2 releases it from the membrane. Cyclooxygenases make prostaglandins and thromboxane from it, lipoxygenases make leukotrienes. These eicosanoids control fever and pain perception, vessel width, blood clotting, the protection of the stomach lining and blood flow to the kidneys. Arachidonic acid also gives rise to lipoxins, which help to end an inflammation, and to endocannabinoids such as anandamide.

Low arachidonic acid – what happens in the body?

When there is little arachidonic acid in the membranes, less starting material for prostaglandins, thromboxane and leukotrienes is available in response to a stimulus; inflammatory and clotting reactions are then weaker. Because the same membrane positions can also be occupied by EPA, the AA share falls when a lot of EPA is built in. Low values also occur with a very low intake of animal fats, with disorders of fat absorption and with reduced conversion from linoleic acid. Arachidonic acid is also needed for tasks that have nothing to do with inflammation: it is an important building block of cell membranes in the brain, and some of its prostaglandins protect the stomach lining and maintain blood flow to the kidneys.

High arachidonic acid – what happens in the body?

When the membranes contain a lot of arachidonic acid, more of it is released and converted into messengers with every stimulus. Prostaglandin E2 widens vessels, makes nerve endings more sensitive to pain and promotes fever; thromboxane A2 makes platelets clump and vessels narrow; leukotriene B4 attracts white blood cells, and other leukotrienes narrow the airways. Inflammatory reactions are therefore stronger. A high value occurs with a plentiful intake of animal fats and with few omega-3 fatty acids, which compete with arachidonic acid for membrane positions and enzymes. The value alone does not show whether inflammation is actually taking place; it describes the raw material stored in the membranes.