Fatty acids are not just fuel — they are structural components of every cell membrane, precursors to critical signalling molecules, and among the most modifiable risk factors in preventive medicine.
Fatty acids are the building blocks of the lipid bilayer in every cell membrane. Their composition directly influences membrane fluidity, receptor function, and the body’s inflammatory and resolving pathways.
Every cell in the body is enclosed by a lipid bilayer made largely of fatty acids. The types of fatty acids incorporated into these membranes determine their fluidity, permeability, and the behaviour of embedded proteins including receptors and ion channels.
Fatty acids are precursors to eicosanoids, prostaglandins, leukotrienes, and specialised pro-resolving mediators (SPMs). These molecules regulate inflammation, blood clotting, blood vessel tone, immune responses, and tissue repair.
Unlike many biomarkers, membrane fatty acid composition is directly modifiable through dietary intake. Changes in diet or supplementation are reflected in cell membranes within weeks, with full equilibration over 3–4 months.
Fatty acids are classified by their chemical structure — the number of carbon atoms, the number of double bonds, and the position of those bonds. Each class has distinct biological roles.
ALA, EPA, DPA, DHA
Anti-inflammatory and cardioprotective. EPA and DHA are the biologically active forms found in marine sources. ALA (from plants) is an essential precursor but converts poorly (<5%) to EPA/DHA. Omega-3s are precursors to specialised pro-resolving mediators (SPMs) that actively resolve inflammation. Most Western diets are deficient in EPA and DHA.
LA, GLA, DGLA, AA
Essential for growth, immune function, and brain development. Linoleic acid (LA) is the predominant dietary omega-6 and is abundant in vegetable oils. Arachidonic acid (AA) is the primary precursor to pro-inflammatory eicosanoids. While essential, excessive omega-6 relative to omega-3 may promote a pro-inflammatory state.
Oleic acid (OA), palmitoleic acid
Oleic acid (the primary fatty acid in olive oil) is associated with cardiovascular benefit in Mediterranean diet studies. MUFAs improve membrane fluidity and are generally considered neutral to beneficial in the context of heart disease risk.
Palmitic acid, stearic acid, myristic acid
Important structural and energy-storage fatty acids. Found in animal fats, dairy, and tropical oils. The relationship between saturated fat intake and cardiovascular disease is more nuanced than historically believed, with chain length and food matrix playing important roles.
Omega-3 and omega-6 fatty acids compete for the same enzymatic pathways. The ratio between them influences whether the body favours pro-inflammatory or pro-resolving outcomes.
Ancestral human diets are estimated to have provided omega-6 and omega-3 in roughly equal proportions.1 The modern Western diet, rich in vegetable oils and processed foods, has pushed this ratio to approximately 15:1 or even 20:1 in favour of omega-6.
This shift has occurred largely through increased consumption of soybean oil, corn oil, and sunflower oil in processed and fried foods, combined with reduced intake of fatty fish and other marine sources of EPA and DHA.
Omega-6 arachidonic acid (AA) is the primary precursor to pro-inflammatory eicosanoids (prostaglandin E2, leukotriene B4). Omega-3 EPA competes with AA for the same cyclooxygenase and lipoxygenase enzymes, producing less inflammatory mediators and generating anti-inflammatory resolvins and protectins.2
A lower omega-6:omega-3 ratio shifts the balance toward resolution of inflammation rather than its perpetuation — relevant to cardiovascular disease, autoimmune conditions, and metabolic syndrome.
Not all omega-3s are created equal. Understanding the differences between ALA, EPA, and DHA is essential for clinical guidance.
Eicosapentaenoic acid. A 20-carbon omega-3 with five double bonds. Primary source: fatty fish and fish oil. EPA is the main precursor to anti-inflammatory eicosanoids and resolvins. It competes directly with arachidonic acid (AA) for inflammatory pathways. Particularly relevant for cardiovascular health, inflammation management, and mental health.
Docosahexaenoic acid. A 22-carbon omega-3 with six double bonds. DHA comprises approximately 40% of the polyunsaturated fatty acids in the brain and 60% in the retina. It is critical for neural development, cognitive function, and visual acuity. Particularly important during pregnancy, infancy, and for cognitive health across the lifespan.
Alpha-linolenic acid. An 18-carbon essential omega-3 found in flaxseed, chia, hemp, and walnuts. ALA is the only omega-3 classified as “essential” (the body cannot synthesise it), but conversion to EPA is limited to approximately 5–10%, and conversion to DHA is less than 1%. ALA alone is insufficient to raise the Omega-3 Index to the target range.
Omega-3 deficiency is one of the most prevalent nutritional inadequacies in Western populations, yet it remains under-recognised and under-tested in clinical practice.
Most patients and many clinicians assume that omega-3 status is adequate if some fish is consumed or a supplement is taken. In practice, supplementation with standard-dose fish oil often fails to raise the Omega-3 Index above the 8% target.4 Without testing, there is no way to confirm adequacy.
Dietary recall is particularly unreliable for fatty acid intake. The type of fish, preparation method, frequency, serving size, and competing dietary fats all influence actual omega-3 absorption and tissue incorporation.
Measuring fatty acid status transforms omega-3 management from guesswork to evidence-based practice. A baseline test quantifies the deficit, a follow-up confirms response, and longitudinal monitoring tracks compliance — the same measure–intervene–recheck cycle used for cholesterol and HbA1c.
For clinicians managing cardiovascular risk, cognitive decline, pregnancy, inflammation, or mental health, fatty acid testing adds an objective, actionable data point that dietary history alone cannot provide.
Fatty Acid Labs offers a range of validated fatty acid tests, each targeting specific clinical questions. All are measured from red blood cell membranes using GC-FID — the reference method for fatty acid analysis.
EPA + DHA as a percentage of total RBC fatty acids. The most validated single biomarker for omega-3 status and cardiovascular risk. View test →
Omega-3 Index plus AA:EPA ratio and Omega-6:Omega-3 ratio. Provides a fuller picture of inflammatory balance for patients with chronic inflammatory conditions. View test →
Full quantification of 24+ individual fatty acids across all classes — saturated, monounsaturated, omega-3, omega-6, and trans fats. The most comprehensive view of a patient’s fatty acid status. View test →
Targeted DHA measurement for pregnant and breastfeeding women. Ensures adequate DHA status for foetal brain and retinal development during the critical window. View test →
Partner with Fatty Acid Labs for validated, scalable fatty acid testing. From Omega-3 Index to complete profiles — wholesale pricing, branded kits, and full laboratory support.