What is DHA omega-3?

The molecule, and its four addresses in the body

What DHA omega-3 is begins with the molecule and ends with where it lives, because DHA is defined as much by its addresses as by its chemistry. The molecule: DHA, docosahexaenoic acid, is a fatty acid of twenty-two carbons with six double bonds, the longest and most unsaturated fatty acid in the human diet, an omega-3 because its first double bond sits three carbons from the tail, and a molecule so kinked by its six bonds that it packs loosely and keeps whatever membrane it sits in fluid, which is the property every one of its jobs depends on. Its four addresses. The brain: DHA is the most abundant omega-3 in the brain, a large share of the fatty acids in grey matter and the synaptic membranes where signalling happens, accumulated in the last trimester and the first two years of life and maintained by the diet after, the reason the maternal and brain claims exist. The retina: the photoreceptors' outer segments, the membranes that hold the light-sensing pigment, are among the most DHA-rich membranes in the body, their fluidity letting the pigment respond to light, the reason the vision claim exists. Sperm: DHA is concentrated in sperm membranes, particularly the tail, where fluidity is motility, the men's fertility file's mechanism. And every cell membrane: DHA sits in the phospholipid bilayer of red cells, heart muscle and skeletal muscle, where the omega-3 index measures it, keeping membranes fluid and supplying, alongside EPA, the resolving mediators the inflammation literature studies. Four addresses, one property, fluidity.

The three sentences DHA holds on its own, the two sources, the label read, and DHA filed

DHA holds three register sentences of its own, more than any other single omega-3, and each maps to an address. Brain: DHA contributes to the maintenance of normal brain function, at 250mg of DHA a day, a maintenance sentence describing what adequate DHA supports and not a memory or cognition-improving claim. Vision: DHA contributes to the maintenance of normal vision, at the same 250mg, the retina's sentence. Maternal: maternal intake of DHA contributes to the normal brain development and normal eye development of the foetus and breastfed infants, at 200mg of DHA a day in addition to the adult 250mg of EPA and DHA, the one place where a specific reader's DHA need is higher, and the pregnancy page's rule that the source is a body oil or an algal DHA and never a liver oil. DHA also shares the combined sentences with EPA, heart function at 250mg of the two together and triglycerides and blood pressure at two and three grams. The two sources: marine algae make DHA and oily fish concentrate it, so a standard fish oil supplies it at a 3 to 2 EPA to DHA ratio, 120mg in a 1000mg softgel, which reaches the combined heart claim in one softgel and the DHA claims at two or three, and an algal oil supplies it DHA-first, 200 to 400mg a capsule with little EPA, the vegan's source and the DHA-claim reader's shortcut. The body's own supply is negligible, ALA from plants converting to DHA at well under one percent. The label read follows: a reader who wants the brain, vision or maternal sentences reads the DHA line rather than the omega-3 total or the combined EPA and DHA figure, and buys the softgels or the algal capsule that reach 250mg of DHA specifically. DHA filed: the longest omega-3, four addresses in the brain, retina, sperm and every membrane, three sentences of its own at 250mg and 200mg more, two sources in fish and algae, and a DHA line to read, with the worked example being 120mg a softgel and the DHA claims at two or three, £14.99 for 90 at 17p.

The verdict, a molecule defined by six bonds and four addresses

What is DHA omega-3: docosahexaenoic acid, the longest and most unsaturated omega-3 at twenty-two carbons and six double bonds, made by marine algae and concentrated in oily fish, living at four addresses, the brain's grey matter where it is the most abundant omega-3, the retina's photoreceptors, sperm membranes and every cell membrane it keeps fluid, and holding three register sentences of its own, the maintenance of normal brain function and normal vision at 250mg of DHA a day and the maternal claim at 200mg more in pregnancy and breastfeeding, supplied by a standard fish oil at 120mg a softgel and by an algal oil DHA-first, with the DHA line rather than the omega-3 total being the number a reader of those sentences reads. 120mg a softgel: Futuro Labs Omega 3 Fish Oil, 1000mg fish oil providing 180mg EPA and 120mg DHA, 90 for £14.99 at 17p a day, the DHA claims at two or three.

What to check on the label

Questions people also ask

What does DHA do in the body?

It keeps membranes fluid at four addresses: the brain's grey matter and synapses, where it is the most abundant omega-3, the retina's photoreceptors, sperm membranes where fluidity is motility, and every cell membrane, where the omega-3 index measures it and where, with EPA, it supplies the resolving mediators.

What health claims can DHA make?

Three of its own, the maintenance of normal brain function and normal vision at 250mg of DHA a day and the maternal claim that maternal DHA supports foetal and infant brain and eye development at 200mg more, plus the combined sentences with EPA for heart function, triglycerides and blood pressure.

How much DHA is in a fish oil capsule?

Around 120mg in a standard 1000mg softgel at the usual 3 to 2 EPA to DHA ratio, which reaches the combined heart claim in one softgel and the 250mg DHA brain and vision claims at two or three, while an algal capsule carries 200 to 400mg of DHA and reaches them in one.

Is DHA vegan?

The molecule is made by marine algae, so an algal oil supplies DHA directly for a vegan, DHA-first with little EPA, while plant omega-3 from flax, chia and walnuts is ALA, converted to DHA at well under one percent.

Should I take DHA or EPA?

For the brain, vision and maternal sentences, DHA specifically, read from the DHA line; for the heart, triglyceride and blood pressure sentences, the two combined in any ratio; and a standard 3 to 2 fish oil serves both at the right softgel count.

Sources

1. EFSA Panel on Dietetic Products. Scientific opinion on health claims related to DHA: maintenance of normal brain function and normal vision (250mg DHA daily condition of use). EFSA Journal 2010;8(10):1734. https://www.efsa.europa.eu/en/efsajournal/pub/1734
2. Commission Regulation (EU) No 440/2011 authorising the claim that maternal DHA intake contributes to the normal brain and eye development of the foetus and breastfed infant, conditional on 200mg of DHA a day in addition to the adult 250mg of EPA and DHA. https://eur-lex.europa.eu/eli/reg/2011/440/oj
3. The alpha-linolenic acid conversion literature: the plant omega-3 ALA from flax, chia, walnuts and rapeseed is converted to EPA at a few percent and to DHA at well under one percent in most adults, higher in women of childbearing age and lower on a high omega-6 diet, so plant sources do not reliably supply EPA and DHA. PubMed record
4. The omega-3 and male fertility literature: DHA is concentrated in sperm membranes, observational studies associate higher fish and omega-3 intake with better semen parameters, and small randomised trials report improved sperm quality with omega-3 supplementation in men with poor parameters, with no authorised fertility claim. PubMed record

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