Alpha-Linolenic Acid (ALA)

🧬 Family & Essentiality

🌿 Plain-Language Summary

Alpha-linolenic acid (ALA) is the essential omega-3 fatty acid found mainly in plant foods. The body converts small amounts of ALA into long-chain omega-3s like EPA and DHA, though the conversion rate is low. Regular dietary intake is necessary to support general cell health and metabolic function.

⚗️ Molecular & Chemical IDs

• C₁₈H₃₀O₂ • 18:3 (n-3)
• CAS Number: 111-71-7
• Solubility: Fat-soluble — absorbed with dietary lipids
• Structure: Three double bonds; first at the third carbon from omega end

⚡ Functions

• Maintains normal membrane fluidity and lipid structure
• Precursor to EPA → resolvins/protectins involved in inflammation resolution
• Supports cardiovascular and general metabolic health

🍽️ Absorption & Bioavailability

Only ~5–10 % of ALA converts to EPA and < 1–5 % to DHA in adults. Direct marine or algal sources are often required for optimal long-chain omega-3 status.

🇦🇺 Australian NRVs (NHMRC)

• Adequate Intake (AI): 1.3 g/day (men) | 0.8 g/day (women)
• Based on NHMRC Nutrient Reference Values
• No Upper Limit (UL) established for ALA from foods

🚨 Deficiency & Insufficiency

Insufficiency

Rare, but very low omega-3 diets may show dry skin, poor wound healing, or altered lipid profiles (context-dependent).

Excess

• Very high supplemental intakes may affect blood lipid ratios; consult a clinician if using concentrated oils.

🥗 Food Sources

• High ALA foods: Flaxseed (linseed), chia seeds, hemp seeds, walnuts, canola and soybean oil
• Moderate ALA sources: Leafy greens (spinach, kale), edamame, perilla oil

ALA is the plant-based omega-3 precursor that complements marine EPA and DHA from fish or algae. See also the Omega-3 Overview page.

🧪 Testing & Monitoring

• Omega-3 Index (% EPA + DHA in red blood cells) — ALA not directly measured routinely
• Plasma fatty acid profile available in specialised labs (context-specific)
• Consult a healthcare provider for personalised assessment

🔗 Interactions

• Competes for Δ6-desaturase with omega-6 (LA)
• Conversion to EPA/DHA enhanced by adequate zinc and vitamin B6 status
• Antioxidants (vitamin E) help stabilise ALA-rich oils against oxidation

Compare fat families: Omega-6 • Omega-9

📊 Evidence Snapshot

• 🔬✅ Established: Essential nutrient role for membrane PUFA composition and EPA/DHA precursor function
• 🧪⚖️ Promising: Associations with heart and metabolic health via dietary intake patterns
• ⚠️❌ Unproven: Direct ALA supplement claims for disease treatment or rapid conversion to EPA/DHA

Explore related pages: EPA (Eicosapentaenoic Acid) • DHA (Docosahexaenoic Acid)