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Table 4 Studies outlining the effects of supplementing dietary gamma-linolenic acid on changes in plasma/serum phospholipid arachidonic acid level

From: Increasing dietary linoleic acid does not increase tissue arachidonic acid content in adults consuming Western-type diets: a systematic review

Author, (reference) Study design Subjects Diet length GLA source, amount supplemented (g/d) Δ AA (%) change Comments
Ebden [52] Double-blind intervention N = 6 8 weeks Efamol oil (0.36) 6.1 (N.S.) No crossover with placebo. Subjects were asthmatics used medication or bronchodilator.
Thavonen [29] Randomized, double-blind crossover N = 15 3 weeks Black current seed oil (0.38) 3.7 (N.S.) Subjects aged 55-75 years old
Theis [45] Double-blind parallel interventions N = 8 12 weeks GLA-rich triacylglycerol capsules (0.77) 27 (p < 0.05) Subjects consumed capsules for 12 weeks. AA changed only on 12th week.
Yaqoob [34] Double-blind parallel intervention N = 8 12 weeks Evening primrose oil (1.06) 14 (N.S.)  
Mills [28] Randomized double-blind parallel intervention N = 10 28 days Borage oil (1.30) 12 (p < 0.05) AA data available for only pre and post intervention (28 days)
Miles [27] Randomized double-blind intervention N = 8-12 12 weeks Borage oil capsules (2.00) 15 (p < 0.05) Consumed capsules for 12 weeks. AA only increased after the 8th week, no difference after 8th week.
Johnson [53] Pre-post intervention N = 5 3 weeks Ultra-GLA capsules (6.00) 31 (p < 0.05)  
  1. Percent change (±) from baseline in AA that is significant is identified with (p < 0.05). Percent change (±) from baseline in AA that is not significant is denoted by N.S.
  2. Abbreviations: AA, arachidonic acid; GLA, gamma-linolenic acid