Omega-3s are said to be anti-inflammatory. Omega-6s are said to be pro-inflammatory.
So often repeated, this opposition seems almost obvious. Yet, our body works in a much more subtle way.
Omega-3s and omega-6s are not two opposing camps. They are two families of fatty acids that, among other things, help build our cell membranes and produce many biological messages.
Their story becomes truly interesting when we look at inflammation.
Omega-3s and omega-6s: two families we need
Omega-3s and omega-6s are polyunsaturated fatty acids.
On the omega-3 side, the dietary starting point is ALA, or alpha-linolenic acid. Our body can convert some of it into EPA and then DHA, but not easily or efficiently. On the omega-6 side, the main precursor is linoleic acid, or LA, which can notably lead to the formation of arachidonic acid, or ARA.
ALA and LA have one essential thing in common: our body cannot make them. They must therefore be obtained from food. They are classified as essential fatty acids.
Some of their conversion pathways use common enzymes, creating metabolic interactions and competition between the two families. But that is not enough to summarise their balance in a single ratio: the actual amounts consumed also matter.
To distinguish ALA, EPA, and DHA more precisely, discover our article Omega-3s: where to find them and how much to eat
Why do omega-6s have this "inflammatory" reputation?
This reputation is based on a biological reality, but it has often been oversimplified.
Arachidonic acid, an omega-6 found in our cell membranes, can be converted into molecules that help trigger or amplify an inflammatory response.
This observation has largely fuelled the equation: omega-6 = inflammation.
But eating more linoleic acid does not mean that the body automatically and massively converts it into inflammatory molecules. Human studies generally do not show that increasing LA intake increases the main markers of inflammation.
In other words: omega-6s can contribute to inflammation without being "inflammatory" nutrients by definition.
Inflammation: an alarm that must also know how to stop
To understand the role of the two families, we must abandon another misconception: inflammation is not always an enemy.
First, sound the alarm. Acute inflammation is first and foremost a natural defence mechanism. When tissue is injured or an infectious agent appears, the body quickly mobilises its defence cells.
Redness, heat, swelling, pain: these manifestations show that the alarm is working.
Some messengers derived from omega-6s participate in this first phase. If you cut your finger or need to fight an infection, this is exactly the response you want to be triggered.
The problem arises when it becomes excessive, prolonged, or when the body struggles to return to balance.
Imagine an alarm in your home: useful if it sounds when an intruder appears, much less so if it continues for hours after they leave.
Next, organise the return to calm. This is the often-forgotten point: the end of inflammation is not merely passive. The body also produces mediators that actively participate in its resolution.
Once again, the "bad omega-6 / good omega-3" classification no longer holds.
Arachidonic acid can be used to produce lipoxins, which are involved in resolving inflammation. For their part, EPA and DHA can give rise to other mediators, notably resolvins, protectins, and maresins.
There is no need to remember all these names. The essential thing is the image: an inflammatory response looks more like an orchestra or a ballet than a switch.
Some messengers start the response, others amplify it, and still others help to slow it down and restore balance.
Should we then eat fewer omega-6s?
Not necessarily.
In France, nutritional authorities recommend that the ratio between the two precursors LA and ALA tend toward 5. However, this ratio does not constitute, on its own, a recommended nutritional intake. This figure does not mean that you should calculate all your omega-6s and all your omega-3s every day to get exactly 5.
A ratio can also be misleading: it can be improved by reducing omega-6s or increasing omega-3s, while these two situations do not tell the same story nutritionally.
In practice, you do not have to declare war on the vegetable oils, seeds, or nuts that provide you with omega-6s.
It is especially useful not to forget omega-3 sources: rapeseed oil, walnuts, flax or chia seeds for ALA, oily fish or certain microorganism oils for EPA and DHA.
Omega-3s and omega-6s: move beyond the duel
Omega-3s and omega-6s are ultimately not two adversaries. They provide our cells with different building blocks from which the body makes messages that help trigger, control, and resolve inflammation.
The true balance is therefore not to prevent all inflammation, nor to eliminate a family of fatty acids. It consists rather in allowing this alarm to sound when it is useful… and then to switch itself off.
To continue our exploration:
→ Omega-3s: where to find them and how much to eat