Health⏱ 4 min read
How to Calculate Your Omega-3 Intake and Whether You Are Getting Enough
Omega-3 fatty acids are the most under-consumed nutrient in Western diets. Here is how to calculate your EPA and DHA intake, convert ALA to the active forms, and assess whether you need a supplement.
Not all omega-3s are equal. ALA (from plant sources) and EPA/DHA (from oily fish) have fundamentally different roles. Most dietary advice focuses on total omega-3 but the conversion from ALA to EPA/DHA is far lower than commonly assumed.
The Three Types of Omega-3
ALA (alpha-linolenic acid): plant-based omega-3
Sources: flaxseed, chia, walnuts, rapeseed oil
UK adequate intake: 2g ALA/day for adults
EPA (eicosapentaenoic acid): marine omega-3
Role: anti-inflammatory, cardiovascular health
DHA (docosahexaenoic acid): marine omega-3
Role: brain function, eye health, pregnancy, infant development
ALA to EPA conversion: approximately 8-20%
ALA to DHA conversion: approximately 0.5-4% (very inefficient)
This means plant-based omega-3 provides almost no DHA.
A vegan eating 4g ALA/day converts approximately:
EPA: 4g x 15% = 0.6g EPA
DHA: 4g x 2% = 0.08g DHA -- far below recommended intake
Recommended EPA + DHA Intakes
General adult health: 250-500mg EPA + DHA per day
Cardiovascular disease risk reduction: 1,000mg EPA + DHA per day
Triglyceride reduction (therapeutic): 2,000-4,000mg EPA + DHA per day
Pregnancy/breastfeeding: 200-300mg DHA per day minimum
UK National Diet and Nutrition Survey (NDNS):
Average EPA + DHA intake in UK adults: approximately 200-250mg/day
This is below the minimum recommended level for most people.
EPA + DHA in Common Foods
FoodServingEPA + DHA (mg)
Mackerel100g2,000-3,000
Salmon (farmed)100g1,800-2,500
Sardines (tinned)100g1,500-2,000
Tuna (tinned in brine)100g150-350
Cod100g150-250
Cod liver oil (1 tsp)5ml1,000-1,200
Omega-3 supplement (standard)1 capsule180-300
Supplement Dosing Calculation
Check the supplement label: EPA and DHA are listed separately.
A "1,000mg fish oil" capsule may contain only:
EPA: 180mg + DHA: 120mg = 300mg EPA+DHA total
(The remaining 700mg is other fatty acids)
For general health (250-500mg EPA+DHA target):
One standard capsule (300mg EPA+DHA): meets minimum
For cardiovascular risk: need 3-4 standard capsules or 1-2 high-strength
To eat your way to the recommendation (250mg/day):
1-2 portions of oily fish per week achieves this.
NHS recommends 2 portions of fish per week, one of which oily.
Vegetarian/vegan option:
Algae-derived omega-3 oil: directly contains EPA and DHA
Bypasses the inefficient ALA conversion entirely.
Algae is where fish get their omega-3 -- cutting out the middleman.