Hey I’m Gaz, a Plantbased Athlete and known as “The Biohacker of Bath”. The best thing to realize is that not all Science is bad, as long as it is genuinely observable, repeatable and stands up to independent scrutiny. Science can be questioned and tested hard, false information requires nefarious entities to impose censorship over questioning or testing the science by fellow scientists and related “experts” and in worst cases censorship and ‘cancelling’ of previously renowned scientists and experts. Please be aware of this distinction.
The key message is that there is a real conversion pathway, but there isn’t a single “conversion rate” that applies to every human.
ALA, EPA and DHA: The Omega-3 Family — and Why the Conversion Numbers Aren’t Quite That Simple
When people talk about omega-3, it is easy to think of it as one particular nutrient.
It isn’t.
Omega-3 is a family of fatty acids, and three of the most commonly discussed members are:
- ALA — alpha-linolenic acid
- EPA — eicosapentaenoic acid
- DHA — docosahexaenoic acid
They’re all omega-3s, but they’re different fatty acids, with different structures, food sources and biological roles.
🌱 ALA — the plant-based omega-3
ALA is the main omega-3 found in plant foods.
Good sources include:
- Flaxseed and flaxseed oil
- Chia seeds
- Walnuts
- Rapeseed/canola oil
- Soybean oil
ALA is also an essential fatty acid. In other words, humans cannot make it from scratch in sufficient amounts, so we need to obtain it from our diet.
So when someone says that plants provide omega-3, they’re absolutely right.
ALA is a genuine omega-3 fatty acid.
🐟 EPA — a different omega-3
EPA stands for eicosapentaenoic acid.
It’s a longer-chain omega-3 than ALA and is particularly associated with oily fish and seafood.
But there is an interesting twist here.
Fish aren’t the original source of EPA. Marine microalgae are important producers of EPA and DHA at the base of the marine food chain, with these fatty acids subsequently accumulating in marine animals.
This is also why certain microalgae can be used to produce plant-free-from-fish, algae-derived EPA and DHA products.
🧠 DHA — another member of the family
DHA stands for docosahexaenoic acid.
It’s another long-chain omega-3 and is particularly abundant in tissues such as the brain and retina.
Like EPA, DHA is commonly obtained from oily fish and seafood, although algae can provide a direct non-fish source.
So, very simply:
OMEGA-3
🌱 ALA — abundant in many plants 🐟 EPA — abundant in oily fish; also produced by some microalgae 🧠 DHA — abundant in oily fish; also produced by some microalgae
All three are omega-3s.
They’re just different members of the same family.
The main omega fatty-acid families
| Family | Examples | Main dietary sources |
|---|---|---|
| Omega-3 (n-3) | ALA, EPA, DHA | Flax, chia, walnuts, oily fish, algae |
| Omega-6 (n-6) | LA, GLA, AA | Vegetable oils, nuts, seeds, eggs, meat |
| Omega-9 (n-9) | Oleic acid | Olive oil, avocados, nuts |
| Omega-7 (n-7) | Palmitoleic acid | Macadamia nuts, some fish, dairy |
🔄 But can’t we make EPA and DHA from ALA?
Yes.
And this is where things get much more interesting.
The human body has enzymes that can convert ALA through a series of steps into longer-chain omega-3s:
ALA → EPA → DPA → DHA
So it would be incorrect to say:
“Plant omega-3 can’t become EPA or DHA.”
It can.
The more accurate statement is that the conversion is limited, particularly when it comes to DHA.
And this is precisely where quoting one neat percentage can become misleading.
📊 So what percentage of ALA becomes EPA and DHA?
You may see statements such as:
“5% of ALA converts to EPA and 0.5% converts to DHA.”
Or perhaps:
“21% converts to EPA and 9% to DHA.”
The problem isn’t necessarily that these numbers are wrong.
The problem is that they come from different human studies using different experimental approaches and populations.
There isn’t one universally applicable conversion percentage.
One human study found…
A study using stable-isotope-labelled ALA in young women estimated net fractional conversion of ALA at approximately 21% to EPA and 9% to DHA.
Those numbers can look surprisingly high.
But another body of research has produced substantially lower estimates.
A review of human stable-isotope studies reported that conversion to EPA in adult men was around 8%, while conversion to DHA was less than 0.1%. The same review noted substantially greater DHA conversion in women, estimated at around 9% in the studies it examined.
Other modelling work has produced still different estimates, illustrating just how dependent the answer is on the experimental conditions and how conversion is measured.
So which number is “the correct one”?
There isn’t a single number.
And that’s actually the important point.
🔬 Why do the studies produce different numbers?
There are several reasons.
1. Different people convert ALA differently
Sex appears to be one factor.
Research suggests that conversion of ALA to longer-chain omega-3s can be greater in women than in men, potentially influenced by hormonal regulation, including oestrogen.
That makes it difficult to give one conversion percentage and apply it equally to everyone.
2. Diet matters
The amount and type of other fatty acids in the diet can influence ALA metabolism.
For example, human research has examined the influence of both ALA and linoleic acid (LA) intake on ALA conversion and found that the absolute amounts of these fatty acids in the diet can affect metabolism.
In other words, the body isn’t operating in a nutritional vacuum.
The amount of ALA you’re eating, what other fats you’re eating, and the overall dietary pattern can all be relevant.
3. Researchers measure different things
This is a particularly important point.
A study can measure labelled fatty acids appearing in plasma phospholipids, estimate whole-body conversion, look at red blood cells, or use mathematical modelling to estimate metabolic flux.
These aren’t necessarily measuring exactly the same biological event.
One review of human isotope studies specifically highlighted the wide variability between studies in estimated ALA conversion to EPA and DHA.
So comparing two percentages from two different experiments as though they were measuring precisely the same thing can be misleading.
4. The amount of ALA given can be very different
Some studies use relatively high doses of ALA or controlled diets.
Others examine people consuming more realistic dietary amounts.
And the body’s response to a large experimental dose isn’t necessarily equivalent to what happens when someone eats a tablespoon of flaxseed every morning.
🧩 The conversion pathway has a bottleneck
There’s another reason the EPA and DHA numbers shouldn’t simply be treated as interchangeable.
ALA can be converted to EPA relatively readily compared with the subsequent steps toward DHA.
Research consistently finds that conversion beyond EPA, particularly through to DHA, is much more restricted.
This means that saying:
“ALA converts to EPA and DHA”
is scientifically correct.
But saying:
“ALA converts to EPA and DHA at the same rate”
would not be.
It doesn’t.
The pathway has several enzymatic steps, and the conversion becomes increasingly constrained as we move towards DHA.
🌱 So what should we actually say?
Rather than claiming:
“ALA converts to EPA at X% and DHA at Y%.”
a more scientifically responsible statement is:
“ALA can be converted to EPA and DHA in humans, but conversion is limited and varies considerably between individuals and study conditions. Conversion to EPA appears to be greater than conversion all the way through to DHA, with DHA synthesis particularly restricted in many adults.”
That’s much harder to turn into a catchy infographic.
But it’s considerably more accurate.
The U.S. National Institutes of Health similarly describes conversion of ALA to EPA and DHA as very limited, with reported rates below 15%, and notes that obtaining preformed EPA and DHA from foods or supplements is the practical way to increase their levels in the body. Office of Dietary Supplements
🧠 Does that mean ALA is “inferior”?
Not necessarily.
This is another place where the conversation can become unnecessarily polarised.
It would be wrong to conclude:
“ALA doesn’t convert efficiently, therefore ALA is useless.”
ALA is an essential omega-3 fatty acid in its own right, and plant foods containing ALA can absolutely be part of a healthy diet.
The more specific question is:
How much preformed EPA or DHA do you want to obtain?
If the objective is specifically to increase dietary EPA or DHA, consuming EPA or DHA directly is a more predictable way of doing that than relying on ALA conversion.
That doesn’t make ALA “fake omega-3”.
It simply means that ALA, EPA and DHA are different omega-3 fatty acids.
🌱🐟 The simplest way to remember it
Think of omega-3 as a family.
ALA is one family member.EPA is another.DHA is another.
ALA can visit the kitchen and be transformed into EPA and, to a much smaller extent, DHA.
But the kitchen doesn’t work at exactly the same speed for everyone.
Some people may convert considerably more than others. Gender, diet, physiological state and experimental conditions can all influence the observed conversion.
So when you see a statement like:
“Only X% of ALA becomes EPA and Y% becomes DHA.”
it’s worth asking:
“According to which study, in which people, using which method, under which dietary conditions?”
Because human metabolism rarely fits quite as neatly into a percentage as an infographic would like it to. 😉
The bottom line
ALA → EPA → DHA
The pathway is real.
ALA can become EPA.
ALA can become DHA.
But the conversion is limited, variable and generally much more restricted for DHA than for EPA.
That is why it is more accurate to talk about a range of observed conversion under particular circumstances, rather than presenting one percentage as though it applies universally to every human being.
And perhaps most importantly:
ALA, EPA and DHA are all omega-3s.
They’re simply different omega-3s with different food sources, different metabolic pathways and different biological roles.
What About The Other Omegas?
🌱 Omega-6
The most important dietary omega-6 is linoleic acid (LA).
It’s an essential fatty acid, just as ALA is essential on the omega-3 side.
LA can be metabolised through a pathway that ultimately produces longer-chain omega-6 fatty acids, including arachidonic acid (AA).
A simplified pathway is:
LA → GLA → DGLA → AA
Good dietary sources of LA include sunflower, safflower, corn and soybean oils, as well as many nuts and seeds.
🫒 Omega-9
Omega-9 is different because it isn’t considered essential.
The best-known omega-9 is oleic acid, the predominant fatty acid in olive oil.
Your body can manufacture oleic acid, so you don’t have to obtain it from food in the same way that you need ALA and LA.
Common sources include:
- Olive oil
- Avocado
- Almonds
- Hazelnuts
- Peanuts
- Macadamia nuts
🌿 Omega-7
Omega-7 is less frequently discussed.
The best-known member is palmitoleic acid.
It occurs in foods such as macadamia nuts and some fish and dairy products. Unlike ALA and LA, it isn’t an essential fatty acid.
A useful way of looking at the whole picture
You could think of the families like this:
OMEGA FATTY ACIDS
Omega-3 → ALA → EPA → DHA
Omega-6 → LA → GLA → AA
Omega-9 → Oleic acid
Omega-7 → Palmitoleic acid
The number — 3, 6, 7, 9 — refers to the position of the first double bond in the fatty acid’s structure, counting from the omega (methyl) end of the molecule.
And there’s an important nutritional distinction:
Essential doesn’t mean “most important”.
It means the body cannot synthesise enough of that fatty acid itself, so it has to come from the diet.
For humans, ALA (omega-3) and LA (omega-6) are the two major essential fatty acids. EPA, DHA and the longer-chain omega fatty acids can be produced to varying degrees from their precursors, although, as we discussed, those conversion pathways can be quite limited.
Sources
National Institutes of Health — Office of Dietary Supplements
Omega-3 Fatty Acids — Fact Sheet for Health Professionals.
https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
Burdge GC, Wootton SA. (2002)
Conversion of α-linolenic acid to eicosapentaenoic, docosapentaenoic and docosahexaenoic acids in young women.
British Journal of Nutrition, 88(4), 411–420.
https://pubmed.ncbi.nlm.nih.gov/12323090/
Burdge GC, Jones AE, Wootton SA. (2002)
Eicosapentaenoic and docosapentaenoic acids are the principal products of α-linolenic acid metabolism in young men.
British Journal of Nutrition, 88(4), 355–365.
https://pubmed.ncbi.nlm.nih.gov/12323089/
Burdge GC, Calder PC. (2005)
Conversion of α-linolenic acid to longer-chain polyunsaturated fatty acids in human adults.
Reproduction Nutrition Development, 45(5), 581–597.
https://pubmed.ncbi.nlm.nih.gov/16441943/
Goyens PLL, Spikerkoetter U, Zock PL, Katan MB, Mensink RP. (2006)
Conversion of α-linolenic acid in humans is influenced by the absolute amounts of α-linolenic acid and linoleic acid in the diet and not by their ratio.
The American Journal of Clinical Nutrition, 84(1), 44–53.
https://pubmed.ncbi.nlm.nih.gov/16825680/
Plourde M, Cunnane SC. (2007)
Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements.
Applied Physiology, Nutrition, and Metabolism, 32(4), 619–634.
https://pubmed.ncbi.nlm.nih.gov/17622276/
Burdge GC, Calder PC. (2006)
Dietary α-linolenic acid and health-related outcomes: a metabolic perspective.
Nutrition Research Reviews, 19(1), 26–52.
https://pubmed.ncbi.nlm.nih.gov/16723367/
