Flaxseed Oil (ALA)

Overview

• Description: Flaxseed oil is a cold-pressed vegetable oil derived from the seeds of Linum usitatissimum.
• ALA Content: It is particularly rich in α-linolenic acid (ALA), an 18-carbon omega-3 poly-unsaturated fatty acid (PUFA).
• Precursor Role: ALA serves as a dietary precursor for longer-chain n-3 fatty acids (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) in limited amounts.
• Primary Purpose: The primary purpose of flaxseed-oil supplementation is to increase dietary intake of ALA, thereby supporting the body’s inflammatory and metabolic pathways that rely on omega-3 fatty acids.

Benefits

• Cardiovascular Health: Randomized trials show modest reductions in systolic blood pressure (≈2–4 mm Hg) and improvements in lipid profiles (lower triglycerides, modest rise in HDL-C) when 2–4 g/day ALA is consumed (Miller et al., 2021).
• Metabolic Support: ALA supplementation improves insulin sensitivity and lowers fasting glucose in modestly hyperglycaemic adults (Khalili et al., 2020).
• Inflammation & Joint Health: ALA reduces circulating C-reactive protein (CRP) and TNF-α levels, providing modest relief in rheumatoid arthritis and osteoarthritis (Bucher et al., 2022).
• Cognitive Function: Observational data link higher ALA intake to slower cognitive decline; small crossover trials show modest improvements in working memory in older adults (Miller & Calder, 2023).
• Dermatology: Topical or oral ALA improves skin barrier function and reduces transepidermal water loss, likely via enhanced epidermal lipid synthesis.

How It Works

• Essential Fatty Acid: α-Linolenic acid is an essential n-3 PUFA that enters cell membranes as a phospholipid constituent.
• Metabolic Conversion: Once ingested, ALA undergoes Δ6-desaturation, elongation, and β-oxidation to generate EPA and, to a lesser extent, DHA.
• Eicosanoid Modulation: These long-chain metabolites compete with arachidonic acid (AA) for cyclo-oxygenase (COX) and lipoxygenase (LOX) enzymes, shifting eicosanoid production toward less inflammatory prostaglandins (e.g., PGE₁) and resolvins.
• PPAR-α Activation: ALA also activates peroxisome proliferator-activated receptor-α (PPAR-α), enhancing fatty-acid oxidation and improving lipid profiles.
• Vasodilation: In endothelial cells, ALA-derived eicosanoids promote vasodilation via nitric-oxide pathways, contributing to blood-pressure reduction.
• Antioxidant Effect: The indirect antioxidant effect arises from incorporation of ALA into membrane phospholipids, reducing lipid peroxidation and stabilizing cell membranes.

Dosage

• Common Dosage: Clinical trials commonly employ 2–4 g of flaxseed oil (≈1,000–2,000 mg ALA) daily, divided into 1–2 doses with meals to improve absorption and minimize gastrointestinal upset.
• Cardiovascular/Metabolic Goals: For cardiovascular or metabolic goals, 3 g/day (≈1,500 mg ALA) has the strongest evidence base.
• Anti-inflammatory Benefits: Athletes seeking anti-inflammatory benefits often use 1–2 g/day pre-exercise.
• Pregnancy/Lactation: In pregnant or lactating women, 1 g/day is considered safe, but higher doses should be discussed with a health professional.
• High Triglycerides: For individuals with high triglycerides, up to 6 g/day (≈2,500 mg ALA) has been studied, but only under medical supervision.

Safety & Side Effects

• General Tolerance: Flaxseed oil is generally well-tolerated.
• Common Side Effects: The most common side effects are mild gastrointestinal symptoms (bloating, flatulence) and occasional mild skin irritation when applied topically.
• Bleeding Risk: Because ALA can mildly inhibit platelet aggregation, high doses (>5 g/day) may increase bleeding risk, especially when combined with anticoagulants (warfarin, clopidogrel) or antiplatelet agents (aspirin, NSAIDs).
• Contraindications: Contraindications include known hypersensitivity to flaxseed, severe liver disease (impaired ALA metabolism), and patients on high-dose anticoagulants.
• Pregnancy/Lactation Limit: Pregnant and lactating women should limit intake to ≤1 g/day unless directed by a clinician.
• Vitamin E Consideration: Long-term high-dose ALA may reduce vitamin E levels; supplementation with 5–10 mg vitamin E per day can offset this effect.

Chemistry

• Molecular Formula: α-Linolenic acid (ALA) is a poly-unsaturated fatty acid with the molecular formula C₁₈H₃₀O₂.
• IUPAC Name: Its IUPAC name is (9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid.
• Molecular Structure: The molecule contains 18 carbon atoms, a carboxylate head group, and three cis-double bonds located at carbons 9, 12, and 15.
• Unsaturation and Fluidity: The double-bond configuration gives it a highly unsaturated, fluid structure at physiological temperature.
• Oxidative Degradation: The double bonds confer susceptibility to oxidative degradation.
• Storage Considerations: Flaxseed oil is typically stored under nitrogen, in dark bottles, and with an antioxidant (e.g., tocopherols) to protect the ALA from oxidation.
• Physical Properties: The oil’s density (~0.93 g mL⁻¹) and low melting point (~−5 °C) reflect its high unsaturation.

Sources & Quality

• Source Material: Commercial flaxseed oil is extracted from mature Linum usitatissimum seeds.
• Geographical Sources: Primarily grown in Canada, China, and the northern United States.
• Extraction Methods: The most common method is cold-press mechanical extraction, which preserves ALA and native tocopherols.
• Solvent Extraction: Solvent extraction (hexane or ethanol) can increase yield but may reduce antioxidant content.
• High-Quality Supplements: High-quality supplements use cold-pressed, expeller-pressed, or super-critical CO₂ extraction to maintain purity and minimize solvent residues.
• Quality Metrics: Quality metrics include ALA content (≥50 % of total fatty acids), peroxide value (<5 meq O₂/kg), and absence of trans-fatty acids.
• Preferred Sources: Certified organic, non-GMO, and sustainably-grown sources are preferred, as they minimize pesticide residues and preserve the oil’s nutritional integrity.