The omega-3 fat ALA is on the top and the omega-6 fat LA on the bottom.
The number 3 means that the first double bond of the fatty acid molecule is located 3 carbon atoms away from the “omega” end.
Conversely, the double bond in omega-6 fatty acids is located 6 carbon atoms away from the omega end.
Bottom Line: The “omega” naming convention has to do with the placement of the double bond in the fatty acid molecule. Omega-3 fatty acids have the first double bond placed 3 carbon atoms away from the omega end.
The Three Types: ALA, EPA and DHA
There are three main types of omega-3 fatty acids: ALA, DHA and EPA.
It is mostly found in animal products, such as fatty fish and fish oil. However, some microalgae also contain EPA.
It has several functions in the human body. Part of it can be converted into DHA.
DHA (docosahexaenoic acid)
Docosahexaenoic acid (DHA) is the most important omega-3 fatty acid in the human body. It is 22 carbons long.
It is a key structural component of the brain, the retina of the eyes and numerous important parts of the body (7).
Like EPA, it is mostly found in animal products like fatty fish and fish oil. Meat, eggs and dairy products from grass-fed animals also tend to contain significant amounts.
Vegetarians and vegans are often lacking in DHA, and should take microalgae supplements, which contain DHA (8, 9).
Bottom Line: There are three main omega-3 fatty acids in the diet: ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).
The Omega-6:Omega-3 Ratio
Omega-6 fatty acids also have important roles in the human body.
Their function is often similar to the function of omega-3 fatty acids.
Both are used to produce signalling molecules called eicosanoids, which have various roles related to inflammation, blood clotting and others (10).
Omega-3 fatty acids are anti-inflammatory, but eating too much omega-6 counteracts these beneficial effects.
For this reason, we need to consume these fatty acids in a certain balance for optimal health. This balance between omega-6 and omega-3 is often termed the omega-6:omega-3 ratio.
These days, most people are eating way too many omega-6 fats, and way too few omega-3s, so the ratio is currently skewed far towards the omega-6 side (11).
Bottom Line: Omega-3 and omega-6 fatty acids are used to produce important signalling molecules called eicosanoids. Getting both types of fatty acids in a certain balance is considered important for optimal health.
What Omega-3 Fatty Acids Do
Omega-3 fatty acids, particularly DHA, play structural roles in the brain and retina of the eyes (7).
It is particularly important for pregnant women and breastfeeding mothers to get enough DHA.
It can affect the future health and intelligence of the baby (12).
Additionally, getting enough omega-3 fatty acids can have powerful health benefits for adults as well. This is especially true of the longer-chain forms, EPA and DHA.
Although evidence is mixed, studies have shown that omega-3 fatty acids can have protective effects against all sorts of diseases.
This includes breast cancer, depression, ADHD, as well as various inflammatory diseases (13, 14, 15, 16).
At the end of the day, omega-3 fatty acids are important, and the modern diet is severely lacking in them.
If you don’t like fish, then consider taking a supplement. It is both cheap and effective.
This article is the first in a series on omega-3 fatty acids. Keep posted for more.