DHA (docosahexaenoic acid)

An omega-3 fatty acid – it is the most abundant polyunsaturated fatty acid in the brain. Essential for neuronal membrane fluidity, synapse formation and vision (in the photoreceptor cells of the retina it is the most abundant polyunsaturated fatty acid).

What DHA does in the body

Docosahexaenoic acid (DHA) has 22 carbon atoms and six double bonds, which makes it the most highly unsaturated fatty acid in cell membranes. Its many double bonds make the chain very flexible; it keeps membranes supple and influences how the receptors, ion channels and transport proteins within them work. The synapses of the grey matter and the membrane stacks of the photoreceptor cells in the retina are particularly rich in DHA, where it supports the work of the visual pigment rhodopsin. DHA reaches the brain mainly bound as lysophosphatidylcholine via the transporter MFSD2A at the blood-brain barrier. DHA also gives rise to D-series resolvins, protectins and maresins – messengers that help to actively end an inflammation.

Low DHA – what happens in the body?

When DHA is lacking, the body builds an omega-6 fatty acid of similar chain length (docosapentaenoic acid n-6) into the membranes in its place, but this has fewer double bonds. The membranes of nerve and photoreceptor cells become less supple as a result, and signal transmission at synapses and in the retina changes. At the same time, less starting material is available for resolvins, protectins and maresins. Studies have observed low DHA values in depressed mood and in declining memory in older age. Because the body makes DHA from ALA only to a small extent, the level depends heavily on intake; during pregnancy and breastfeeding the mother passes DHA on to the child, and her own level can fall.

High DHA – what happens in the body?

A high value usually reflects a plentiful intake over weeks to months, because the red blood cells in which it is measured live for about four months. More DHA in the membranes displaces omega-6 fatty acids and with them part of the starting material for prostaglandins from arachidonic acid. At the same time, the many double bonds make DHA susceptible to oxidation; the membranes therefore depend on antioxidant protective systems such as vitamin E. In the liver, long-chain omega-3 fatty acids slow the production of VLDL, which lowers triglycerides; in some studies LDL rose slightly at the same time. Very large amounts of long-chain omega-3 fatty acids can dampen the clumping of platelets.

The interpretation is given in your report.