Also known as: ARA, 20:4n-6, Omega-6 fatty acid, X-Factor
Muscle & RecoveryEmerging evidence
An omega-6 fatty acid taken deliberately to amplify the inflammatory signal that follows training. It runs against everything people assume about omega-6, and the reasoning behind it is sound.
Typical dose
500.0–1500.0 mg per day
Daily with food, alongside resistance training
What it is
Arachidonic acid is a long-chain omega-6 fatty acid found in meat, eggs and dairy, and present in every cell membrane in the body. Supplements are usually derived from fungal fermentation rather than animal sources.
Its position in the supplement market is unusual. Most of the industry sells things that reduce inflammation; this is taken to increase a specific inflammatory signal on purpose.
That sits on a real observation. The local inflammatory response to resistance training is part of how muscle adapts to it, and blunting that response too aggressively appears to blunt the adaptation as well.
How it works
Arachidonic acid is the substrate for prostaglandins, particularly PGF2 alpha, which is released by muscle following mechanical loading and is directly involved in signalling muscle protein synthesis.
Supplementing raises the arachidonic acid content of muscle membranes, increasing the amount of substrate available when training triggers that release.
There is an important corollary. Anti-inflammatory painkillers work by blocking the enzyme that converts arachidonic acid to prostaglandins, which is why habitually taking them around training may work against the adaptation you are training for.
What the evidence shows
A controlled trial in resistance-trained men reported significant improvements in peak power and in the response to training over eight weeks, alongside favourable changes in muscle thickness.
An earlier trial in trained men found smaller effects, with improvements in some performance measures and not others.
The total body of human work is small, at a handful of trials in trained populations. The mechanism is well characterised and the direction of the findings is consistent, and the number of studies is genuinely limited.
Dosing
Trials have used 250 to 1,500 mg daily, with 1,000 mg over eight weeks the most commonly cited protocol.
Take it with food, and take it consistently rather than only on training days, since the point is to raise the arachidonic acid content of muscle membranes over time.
Two practical points. It works alongside hard resistance training and has nothing to amplify without it. And habitually taking anti-inflammatory painkillers around training blocks the pathway this depends on, so the two work against each other. Trials generally ran eight weeks, and cycling it rather than taking it indefinitely is the common approach.
At a glance
Common forms
Arachidonic acid (fungal-derived), ARA softgels, Within muscle-building formulas
Half-life / duration
Membrane incorporation over weeks; trials ran 8 weeks
Timing
Daily with food, alongside resistance training
Competition status
Permitted — not on the WADA Prohibited List
Category
Muscle & Recovery
Safety and side effects
Arachidonic acid has been well tolerated in the trials conducted, with no significant adverse effects reported and no unfavourable changes in blood markers at the doses used.
It is a normal dietary fat, and a typical diet already supplies a few hundred milligrams daily.
Because it increases an inflammatory signalling pathway, anyone managing an inflammatory condition should speak to their doctor first, as should anyone taking regular medication. Long-term data beyond the trial durations is limited.
Who should avoid it
Speak to your doctor before use if you are managing an inflammatory condition or take regular medication. Anti-inflammatory painkillers block the pathway this works through, so the two work against each other. Long-term data is limited. Not established in pregnancy or breastfeeding. Not suitable for under-18s.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
