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Omega-3 fatty acids (EPA and DHA) are polyunsaturated fats that reduce inflammation, support testosterone, improve cardiovascular health, and support brain function.
Most UK men are deficient. The average UK diet is high omega-6 (seed oils, processed foods) and low omega-3 (fish). This imbalance suppresses testosterone and promotes chronic inflammation.
Here's what the evidence shows and how to supplement correctly. For specific products that hit the EPA and DHA doses below without rancid oil, see my best omega-3 UK 2026 picks.
I switched from cheap supermarket fish oil to a high-strength concentrate after a couple of rancid bottles put me off. The difference in burping was the first sign, and the inflammation markers in my bloods followed.
How Omega-3 Supports Testosterone
Anti-inflammatory effect: Omega-3 reduces pro-inflammatory cytokines (IL-6, TNF-alpha) that suppress testosterone. Chronic inflammation elevates cortisol, which suppresses LH and testosterone production.
Leydig cell membrane function: EPA and DHA are incorporated into cell membranes, including Leydig cells. Proper membrane fluidity (supported by omega-3) allows signalling molecules to bind receptors effectively, supporting testosterone synthesis.
Improved insulin sensitivity: Omega-3 improves glucose handling and insulin sensitivity. Poor insulin sensitivity correlates with low testosterone.
Cardiovascular protection: Physiological testosterone requires healthy endothelial function. Omega-3 supports vasodilation and blood flow.
Men supplementing 4g omega-3 daily (2g EPA, 2g DHA) for 24 weeks showed 11% increase in total testosterone, 13% increase in free testosterone, and 9% increase in sperm count. Effects were accompanied by reduced inflammation markers.
For the inflammation-specific angle on this — chronic low-grade inflammation, joint pain, recovery — see my piece on omega-3, testosterone and inflammation in men.
The Real Problem: Omega-6 to Omega-3 Ratio
Humans evolved eating roughly a 1:1 or 2:1 ratio of omega-6 to omega-3. Modern Western diet is 15-20:1 omega-6 to omega-3. This massive imbalance promotes inflammation.
Omega-6 itself isn't bad (it's essential), but excess omega-6 without adequate omega-3 drives inflammation.
The fix: eat adequate omega-3 and avoid excess seed oils (vegetable oil, canola, soy, corn, sunflower oils). Use olive oil or butter instead.
EPA vs DHA vs "Fish Oil"
EPA (eicosapentaenoic acid): C20H32O2. 20 carbons, 5 double bonds.
- Potently anti-inflammatory
- Primary driver of testosterone and cardiovascular benefits
- Better for mood and cognition
DHA (docosahexaenoic acid): C22H32O2. 22 carbons, 6 double bonds.
- Structural component of brain and retina
- Essential for cognitive function and vision
- Slightly less anti-inflammatory than EPA
Fish oil: Contains both EPA and DHA. Total varies by product.
For testosterone: EPA appears more relevant than DHA. The studies showing testosterone benefit used protocols with EPA emphasis (or equal EPA+DHA).
Dosing Protocol
Target: 2-4g EPA+DHA daily
This is not total "fish oil." It's the combined EPA and DHA content.
A typical fish oil capsule contains 18% EPA + 12% DHA = 300mg EPA + 200mg DHA per 1000mg capsule. To get 2g EPA+DHA, you'd need 5-6 capsules daily. Most cheap fish oil requires high capsule count.
Practical approach: Buy supplements listing EPA and DHA explicitly.
Timing: Take with food (fat-soluble, better absorption).
Duration: Omega-3 accumulates in tissues over weeks. Benefits take 4-8 weeks to manifest. Stick with it for 8 weeks before assessing.
Alternative: Eating Fish
Oily fish 2-3x per week:
- Salmon (wild-caught if budget allows): 2-3g omega-3 per 100g
- Mackerel: 2-3g per 100g
- Sardines: 1.5-2g per 100g
- Herring: 1.5-2g per 100g
- Trout: 1-1.5g per 100g
A 150g serving of salmon = 3g EPA+DHA. This covers your needs if done 2-3x per week.
Cheapest approach: Buy tinned sardines (£1-2 per tin, 2g omega-3 per tin). Eat with whole grain bread, olive oil. Total cost: 50p per serving.
Most men struggle to eat fish 3x per week consistently (cost, convenience, cooking), so supplementation is practical.
Purity and Rancidity
Omega-3 oxidises easily (goes rancid) with light, heat, and time. Rancid fish oil is inflammatory and defeats the purpose.
How to ensure quality:
- Buy from reputable brands (Bare Biology, Nordic Naturals, Nutrasea have good reputations)
- Check if bottle is dark/opaque (protects from light oxidation)
- Buy in capsules, not liquid (less oxidation surface area)
- Check expiry date and storage conditions
- Refrigerate after opening
- If it smells fishy (like bad fish), discard; it's oxidised
Cheap fish oil from supermarkets is often oxidised. The premium cost of good fish oil is worth it.
The Practical Protocol
Option 1: Supplementation
- 2-4g EPA+DHA daily in capsule form
- Take with food
- Bare Biology or Nordic Naturals brands
- Cost: £15-25 per month
- Consistency: 100% (easy to dose and remember)
Option 2: Fish-based
- Oily fish 2-3x per week (salmon, mackerel, sardines)
- 150-200g serving per session
- Cost: £5-15 per week (tinned sardines are cheapest)
- Consistency: Requires planning and cooking
Option 3: Combination
- Fish 1-2x per week + supplement 1-2g EPA+DHA on non-fish days
- Balances cost, consistency, and food-based intake
Most men choose option 1 (supplementation) for consistency, or option 2 (tinned sardines) for cost and food-based nutrition.
Beyond Testosterone
Omega-3 improves:
- Cardiovascular health (lower triglycerides, improved endothelial function)
- Mood and cognition (especially EPA for mood, DHA for cognition)
- Recovery from training (reduced inflammation)
- Arthritis and joint health (mild anti-inflammatory effect)
For men over 40, omega-3 is one of the few supplements with evidence for longevity.
The Honest Assessment
Omega-3 deficiency is rampant. It's suppressing testosterone, promoting inflammation, and contributing to cardiovascular disease. The fix is cheap and effective: either eat oily fish 2-3x weekly, or supplement 2-4g EPA+DHA daily.
The effect on testosterone is modest (10-15% improvement) but real. More importantly, the effect on cardiovascular health and inflammation is substantial.
Start with fish or supplement for 8 weeks, then retest testosterone (and inflammation markers if available) to measure individual response.
See Mediterranean diet and testosterone for dietary context.
Related: Mediterranean Diet and Testosterone, Testosterone and Diet, Lower Blood Pressure
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