Gamma-Linolenic Acid (GLA)

Clinical evidence supports GLA supplementation for rheumatoid arthritis symptom reduction, with significant improvements in joint tenderness and morning stiffness reported in multiple RCTs. Blackcurrant seed oil provides both GLA and stearidonic acid (an omega-3 precursor), conferring a broader anti-inflammatory lipid profile than evening primrose oil.

Clinical studies with GLA-rich seed oils (evening primrose and blackcurrant) have demonstrated modest benefits in rheumatoid arthritis symptom scores, atopic eczema severity, and mastalgia. A 12-week RCT using blackcurrant seed oil showed significant reductions in joint tenderness and morning stiffness in patients with rheumatoid arthritis. Evidence quality is moderate with some heterogeneity across trials.

A 2013 Cochrane review of GLA supplementation for atopic eczema was inconclusive, though some individual trials showed benefit. A 2014 meta-analysis of GLA for rheumatoid arthritis (6 RCTs, n=339) showed significant reductions in pain, morning stiffness, and joint tenderness with GLA doses of 1.4–2.8 g/day over 6 months. Borage oil provides more GLA per capsule than evening primrose oil (20–26% vs. 7–10%), making it a more efficient delivery vehicle.

GLA is converted to dihomogamma-linolenic acid, leading to anti-inflammatory PGE1 production. Clinical trials demonstrate modest efficacy for cyclical breast pain and PMS symptoms with 1.4-2.8g daily dosing.

Spirulina is one of the few dietary sources of GLA, containing 1-2% of dry weight. GLA supplementation from various sources has shown clinical benefit in rheumatoid arthritis, atopic eczema, and diabetic neuropathy. The GLA content of spirulina contributes to its anti-inflammatory profile but is typically below therapeutic doses used in dedicated GLA trials.