Omega-3 (EPA and DHA): The Evidence Review for Men and Women Over 35

The Two Types of Omega-3: EPA and DHA

Omega-3 polyunsaturated fatty acids come in two main bioactive forms:

EPA (eicosapentaenoic acid, 20-carbon chain):

Primary roles: Anti-inflammatory, cardiovascular, neurological
Strongest evidence for: Depression, inflammation, cardiovascular events
Marine sources (fatty fish, fish oil supplements)

DHA (docosahexaenoic acid, 22-carbon chain):

Primary roles: Neurological, retinal health, cell membrane structure
Strongest evidence for: Cognitive function, eye health, neuroinflammation
Marine sources (fatty fish, fish oil, also some algae)

Both are required for optimal health. You don't choose one—you need both, and the evidence increasingly supports obtaining a combined dose.

The ALA Conversion Problem: Why Plant Omega-3 Is Not Enough

Alpha-linolenic acid (ALA) is the plant-based omega-3 found in flaxseed, chia seeds, and walnuts. It's an essential fatty acid you must obtain from food.

However, the conversion of ALA to EPA and DHA is remarkably inefficient:

ALA to EPA conversion: <5-10% (only 5-10 mg of EPA produced per 100mg of ALA consumed)
ALA to DHA conversion: <2-5% (even worse) (conversion efficiency varies by sex, genetics, and diet — women typically convert at higher rates than men)

This conversion also depends on enzyme availability, zinc status, and insulin levels. A plant-based eater consuming 3g of ALA daily might produce only 150-300mg of EPA and DHA combined.

Practical implication: Plant-based eaters relying on ALA get insufficient EPA and DHA unless they supplement with algae oil. Omnivores eating fatty fish 2-3 times weekly typically meet needs without supplementation.

Cardiovascular Evidence: The REDUCE-IT Trial

The strongest evidence for omega-3 supplementation comes from the REDUCE-IT trial (Bhatt et al. 2019), a randomized controlled trial of 8,179 patients at high cardiovascular risk over 5 years:

Protocol: Icosapent ethyl (highly purified EPA) at 4g daily (2g twice daily) vs placebo.

Results:

25% reduction in cardiovascular events (heart attack, stroke, cardiovascular death)
35% reduction in ischemic events specifically
Benefits emerged within 6-12 months of treatment

This is one of the largest and most rigorous supplement trials ever conducted. The effect size rivals some pharmaceutical interventions.

Critical caveat: Important: REDUCE-IT used pharmaceutical-grade icosapent ethyl (purified EPA) at 4g daily — not standard fish oil. Most consumer fish oil products contain 0.5–2g total EPA+DHA. The REDUCE-IT results cannot be directly extrapolated to standard supplement doses.

Anti-Inflammatory Mechanisms

Omega-3s, particularly EPA, work through several evidence-based mechanisms:

Eicosanoid metabolism: EPA competes with arachidonic acid (omega-6) for incorporation into cell membranes and enzyme substrate. EPA-derived eicosanoids are anti-inflammatory; arachidonic acid-derived ones are pro-inflammatory. Higher EPA shifts the balance toward resolution of inflammation.
Inflammatory cytokine reduction: EPA reduces TNF-alpha, IL-6, and IL-8—key pro-inflammatory cytokines. This is measurable in bloodwork.
Lipid mediator production: EPA and DHA serve as precursors for resolvins and protectins—lipid mediators that actively resolve inflammation. This is distinct from merely blocking inflammatory signals.
Microglia activation: In the central nervous system, DHA suppresses microglial activation, reducing neuroinflammation. Relevant for cognitive ageing and mental health.

The anti-inflammatory effect is dose-dependent. You need 2-4g combined EPA+DHA daily for therapeutic effect. The typical Western diet contains <500mg daily.

The Testosterone Connection

Omega-3s support testosterone synthesis through several mechanisms:

Cell membrane fluidity: Testosterone synthesis occurs in the inner mitochondrial membrane and smooth endoplasmic reticulum. Adequate EPA and DHA maintain optimal membrane fluidity, supporting steroidogenic enzyme function.
LDL and cholesterol transport: Cholesterol is the substrate for steroid hormone synthesis. Omega-3s improve cholesterol metabolism and transport.
Anti-inflammatory support: Chronic inflammation suppresses GnRH and LH, reducing testosterone production. Omega-3s' anti-inflammatory effect supports androgen synthesis indirectly.
Aromatase regulation: Some evidence suggests omega-3s may modestly reduce aromatase activity (enzyme converting testosterone to oestradiol).

While omega-3 won't create supraphysiological testosterone, deficiency in omega-3 status is associated with lower testosterone. In men with poor omega-3 status, supplementation to achieve adequate intake supports testosterone synthesis.

Dosing for Therapeutic Effect

Therapeutic dose (cardiovascular, anti-inflammatory benefit): 2-4g combined EPA+DHA daily.

Preventive/maintenance dose (general health): 1-2g combined EPA+DHA daily.

Optimal ratio: Roughly equal EPA and DHA (e.g., 1g EPA + 1.5g DHA = 2.5g total). Some protocols favour 2:1 EPA:DHA for anti-inflammatory benefit, but 1:1 is fine.

Duration: Steady-state levels take 4-6 weeks. Allow 8-12 weeks to fully assess anti-inflammatory benefit.

Timing: Take with the largest meal of the day (omega-3s are fat-soluble; absorption improves with dietary fat).

Fish Oil vs Algae Oil (Vegan Option)

Fish oil (from fatty fish—sardines, anchovies, mackerel—or fish waste):

Higher EPA and DHA concentration per capsule
Better value per gram of omega-3
Concerns about overfishing (though many use waste products from food industry)
Risk of oxidation if stored improperly
Potential contaminants if sourced from contaminated waters (generally minimal in UK brands)

Algae oil (from microalgae cultures, primarily Phaeodactylum tricornutum or Nannochloropsis):

Suitable for vegans/vegetarians
More sustainable (farmed, not wild-caught)
Higher DHA than EPA (EPA requires further processing)
Generally more expensive per gram
Oxidation risk is lower (controlled cultivation)

For non-vegans, fish oil offers better value and EPA concentration. For vegans, algae oil is the only option.

Key metric: Look at EPA+DHA content per capsule, not "fish oil weight." A 1000mg fish oil capsule might contain only 300mg of combined EPA+DHA.

TOTOX Score: Assessing Oxidation Quality

Omega-3 supplements oxidise easily, forming harmful lipid peroxides. The TOTOX score (total oxidation value) measures this:

Peroxide value (PV): Measures primary oxidation products
Anisidine value (AV): Measures secondary oxidation products
TOTOX = (2 × PV) + AV

Lower TOTOX is better:

<100: Excellent (minimal oxidation)
100-200: Good
200: Poor (oxidised, avoid)

Quality UK brands test and publish TOTOX scores. Bare Biology, for example, typically scores <60.

Store omega-3 supplements in cool, dark conditions (refrigerator is ideal). Once opened, use within 3 months.

UK Brands Worth Considering

Bare Biology Lion Heart (premium):

1400mg combined EPA+DHA per serving (1000mg fish oil + added EPA concentrate)
TOTOX score typically <60 (excellent)
Tested for heavy metals and PCBs
~£20-25 for 60 capsules
Gold standard for quality

Nordic Naturals Ultimate Omega (mid-range):

1280mg combined EPA+DHA per serving
Third-party tested (NSF certified)
Sustainable sourcing
~£12-15 for 60 softgels
Reliable quality

Seven Seas Classic (budget):

480mg combined EPA+DHA per serving (lower dose)
UK institution, widely available in supermarkets
Budget-friendly (~£3-5 for 30-60 capsules)
Lower dose requires 2-3 capsules daily to reach therapeutic effect
Acceptable for maintenance dosing

Wiley's Finest Wild Alaskan Fish Oil (mid-range):

1200mg combined EPA+DHA per serving
Sourced from Alaskan salmon (sustainable certification)
Good TOTOX scores
~£10-13 for 60 capsules
Reliable value

Vitabiotics Omega-3 (budget):

1000mg combined EPA+DHA per capsule
UK-made, available in Boots
Decent budget option
~£6-8 for 60-90 capsules

For vegans: Naturya Vegan Omega-3 (Algae Oil) or Nordic Naturals Vegan Omega-3. Both provide 600-800mg combined EPA+DHA. More expensive (~£12-15), but necessary if vegan.

Testing Omega-3 Status

Medichecks Omega-3 Index Test:

Measures the ratio of EPA+DHA to total fatty acids in red blood cells
Results indicate your tissue omega-3 status (more reliable than serum levels)
Home finger-prick test, results in 3-5 days
Cost: ~£45-55
Target: >8% (optimal is 8-12%)

Testing is optional but useful if you want to confirm supplementation is raising your status. Many people supplement without testing—reasonable if you're consistent with dosing and taking a quality brand.

Practical Supplementation Protocol

Choose a quality brand (Bare Biology, Nordic Naturals, or Wiley's Finest for mid-range)
Aim for 2-4g combined EPA+DHA daily (most people benefit from 2.5-3g)
Take with the largest meal (improves absorption)
Store in cool conditions (refrigerator is ideal)
Give it 8-12 weeks to assess cardiovascular and anti-inflammatory effects
Test if desired (Medichecks Omega-3 Index) to confirm you're in the 8-12% target range

Expected outcomes:

Reduced inflammation markers (C-reactive protein, TNF-alpha)
Improved cardiovascular parameters
Better joint health and recovery
Possible modest mood improvement (EPA and depression evidence)
Support for testosterone synthesis (indirect, through inflammation reduction)

Related Guides

Where to Buy Omega-3 in the UK

Bare Biology: https://www.amazon.co.uk/s?k=bare+biology+lion+heart+fish+oil&tag=maleoptimal-21
Nordic Naturals: https://www.amazon.co.uk/s?k=nordic+naturals+omega+3&tag=maleoptimal-21
Wiley's Finest: https://www.amazon.co.uk/s?k=wiley%27s+finest+omega+3&tag=maleoptimal-21
Amazon UK: https://www.amazon.co.uk/s?k=omega+3+fish+oil+high+strength&tag=maleoptimal-21
Boots: https://www.boots.com/
Tesco/Sainsbury's: Online or in-store (Seven Seas)
Medichecks (for testing): https://www.medichecks.com/

Summary

Omega-3 supplementation, specifically EPA and DHA from marine sources, has the strongest evidence base of any supplement category outside of basic vitamins and minerals.

The REDUCE-IT trial—the largest and most rigorous supplement trial ever—demonstrated 25% reduction in cardiovascular events at 4g EPA daily. Smaller trials consistently show anti-inflammatory benefits, support for testosterone synthesis, and cognitive benefits.

For UK populations:

Take 2-4g combined EPA+DHA daily (therapeutic) or 1-2g (maintenance)
Choose a quality brand with published TOTOX scores and third-party testing
Take with food for optimal absorption
Be consistent—benefits accumulate over 8-12 weeks

Plant-based omega-3 (ALA) converts at <5%, making it insufficient. Plant-based eaters should supplement with algae oil to meet EPA and DHA needs.

Omega-3 supplementation is not flashy, but it's one of the most evidence-supported, practical tools for cardiovascular health, inflammation management, and supporting testosterone synthesis. For UK men and women over 35, it's worth considering a permanent part of your supplementation protocol.