Hemp Seed Oil — Research Profile

What the Research Says

Hemp seed oil research focuses on its unique fatty acid profile — particularly the 3:1 omega-6 to omega-3 ratio and GLA content. Callaway et al. (2005) published the most cited clinical trial in the Journal of Dermatological Treatment, a 20-week crossover RCT showing dietary hemp seed oil significantly improved atopic dermatitis symptoms including dryness, itchiness, and need for medication, compared to olive oil control. The mechanism involves GLA conversion to DGLA, which competes with arachidonic acid in COX/LOX pathways. Schwab et al. (2006) demonstrated favorable changes in plasma fatty acid profiles and cholesterol ratios with hemp seed oil supplementation. Deferne & Pate (1996) characterized the complete fatty acid profile of hemp seed oil, establishing its optimal omega-6:omega-3 ratio and GLA content. The evidence base is smaller than for fish oil or flaxseed oil, with most studies being small-scale. However, the unique combination of balanced omega ratios, GLA, and complete amino acid content makes hemp seed oil a distinctive plant oil worthy of further clinical investigation, particularly for dermatological conditions.

Benefits of Hemp Seed Oil

• Eczema and atopic dermatitis relief — Callaway et al. (2005) published a crossover RCT in the Journal of Dermatological Treatment showing 20 weeks of dietary hemp seed oil significantly reduced symptoms of atopic dermatitis, improved skin dryness, itchiness, and reduced the need for topical medications compared to olive oil placebo
• Anti-inflammatory fatty acid profile — Hemp seed oil's GLA content (2-4% of total fatty acids) is converted to dihomo-gamma-linolenic acid (DGLA), which competes with pro-inflammatory arachidonic acid for COX and LOX enzymes, shifting prostaglandin production from inflammatory PGE2 toward anti-inflammatory PGE1
• Cardiovascular support — Schwab et al. (2006) demonstrated that hemp seed oil supplementation favorably altered plasma fatty acid profiles and reduced total cholesterol-to-HDL ratios in healthy volunteers, attributed to the balanced omega-6/omega-3 ratio and GLA content
• Skin barrier improvement — The balanced essential fatty acid composition supports ceramide synthesis in the stratum corneum, the outermost skin layer; deficiency in essential fatty acids is a well-established cause of impaired skin barrier function and transepidermal water loss
• Immune modulation — Richard et al. (2008) reviewed the immunomodulatory effects of GLA-rich oils, showing that GLA supplementation reduced T-cell proliferation and pro-inflammatory cytokine production in multiple clinical settings, suggesting broad immune-balancing properties

Side Effects and Safety

Safety profile: Generally Safe

Potential Side Effects

• Mild GI discomfort (loose stools, bloating) — most common at higher doses; usually resolves with dose reduction
• Nausea — uncommon, typically when taken on an empty stomach
• Mild anticoagulant effect at high doses — due to omega-3 content; clinically insignificant at standard doses
• Allergic reactions — rare; hemp seed allergies exist but are uncommon
• Potential false positive on THC drug tests — extremely rare with reputable brands that test for THC, but trace contamination is theoretically possible from manufacturing

Drug & Supplement Interactions

• Anticoagulants and antiplatelets (warfarin, aspirin) — omega-3 content may mildly increase bleeding risk at high doses
• Anticonvulsants — theoretical interaction via fatty acid metabolism; no clinical reports but monitor when combining
• Immunosuppressants — GLA modulates immune function; could theoretically alter immunosuppressive drug efficacy
• Other GLA supplements (evening primrose oil, borage oil) — additive GLA intake; calculate total GLA from all sources