As a health-minded individual, you’ve no doubt gotten the memo that omega-3 fatty acids are important. You may dutifully eat your weekly servings of small, oily fish. Perhaps a fish oil pill is even part of your daily supplement routine. But do you know why?
Looking back, I used to write about omega-3s a lot in the early days of Mark’s Daily Apple (more than a decade ago, geez!) Since then, I’ve covered the topic here and there, but I thought it was time for a refresher. Today I’m going to focus on giving you a broad overview of their function and an update on the state of the research literature.
It would be impossible to cover all the reasons that omega-3s are important for health in a single post, nor all the areas of ongoing research. I’ll try to hit the big ones here. Let me know in the comments what else you’d like me to cover in future posts.
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What Are Omega-3 Fatty Acids?
Omega-3s are essential polyunsaturated fatty acids (PUFAs)—“essential” means the body can’t synthesize them. We have to get them from food or supplements.
As Primal folks, you might have an adverse reaction to the word “polyunsaturated.” It’s true that in the ancestral health world, we tend to be wary of PUFAs—or really, oils containing high proportions of PUFAs such as safflower and canola—due to their propensity to become rancid and be pro-inflammatory. However, this is a don’t-throw-the-baby-out-with-the bathwater situation. First, when it comes to overconsumption and inflammation, we are primarily concerned with omega-6 fatty acids, not omega-3s. Second, PUFAs, both omega-3s and even the oft-maligned omega-6s, serve many functions in the human body.
I’ll return to the issue of omega-6s vis-à-vis omega-3s later in this post. For now, I just want you to understand that omega-3s are polyunsaturated, essential, and important.
A Quick Primer on Polyunsaturated Fatty Acids
Omega-3s and omega-6s are both types of polyunsaturated fatty acids. What does this mean? Fatty acids comprise chains of carbon atoms of differing lengths. Picture each carbon atom having four arms. They “hold hands” to form the chain. With the remaining hand(s), they hold on to one or more hydrogen atoms.
If each carbon atom uses one hand to hold the carbon on its left and one to hold the carbon on its right, that leaves two hands free for hydrogen. When each carbon is attached to two hydrogen atoms, these fatty acids are called saturated.
Sometimes carbons form double bonds, meaning they use two hands two grab a neighboring carbon. This leaves only one hand free for hydrogen. These are unsaturated fatty acids. When fatty acids only have one double bond along the carbon chain, they are called monounsaturated. When they have multiple double bonds, they are polyunsaturated.
The number in the name of the fatty acid tells you where you can find the first double bond. In omega-3s, the first double bond is on the third carbon atom from the omega (methyl) end. In omega-6s, it’s on the sixth carbon atom.
Double bonds form “kinks” in the fatty acid chains, affecting the shape, and ultimately the function, of the fatty acid. It is not inherently bad for a fatty acid to be polyunsaturated, but it does mean that they are especially vulnerable to oxidation. Omega-3 and omega-6 fatty acids (along with their less appreciated cousins, the omega-9 fatty acids) are each important in their own way.
The Three Main Types of Omega-3s
There are many forms of omega-3 fatty acids, of which three are particularly noteworthy for humans:
- Alpha-linolenic acid (ALA)
- Eicosapentaenoic acid (EPA)
- Docosahexaenoic acid (DHA)
ALA is the most abundant in the diet. In humans, its main biological function is as a precursor for EPA and DHA. ALA that is not converted to EPA or DHA is used mainly for energy.
Even though ALA is converted into EPA and DHA, the latter two are still considered essential (or “conditionally essential”) because conversion rates are too low to provide all the EPA and DHA needed for optimal functioning. Females are better able to convert ALA thanks to higher estrogen, but both sexes need to get EPA and DHA in their diet and/or from supplements.https://pubmed.ncbi.nlm.nih.gov/23668691/‘>2 https://www.ncbi.nlm.nih.gov/pubmed/29773586‘>4
On the other hand, a Cochrane Review published earlier this year takes a different stance.https://www.ncbi.nlm.nih.gov/pubmed/30415628‘>14 Multiple studies show a benefit, but at doses higher that you’re likely to take over the counter. To reduce triglycerides, the American Heart Association recommends taking 2 to 4 grams of EPA+DHA under a doctor’s supervision.https://www.ncbi.nlm.nih.gov/pubmed/26359502‘>16, and individuals diagnosed with depression may have chronically low levels of omega-3s in their cells.https://www.ncbi.nlm.nih.gov/pubmed/9513745‘>18
Some of the best sources of EPA and DHA are salmon, mackerel, anchovies, sardines, herring, and oysters. Cod livers are delightfully mild and pack a wallop of vitamins A and D to boot. Primal-friendly sources of ALA include flax seeds, chia seeds, and walnuts. You also get some omega-3s in meat and eggs (chickens are often fed omega-enriched feed). Grass-finished beef and pastured eggshttps://pubmed.ncbi.nlm.nih.gov/26795198/‘>32
The primary omega-6 fatty acid is linoleic acid (LA). LA and the primary omega-3 ALA use the same enzymatic pathways to convert into longer-chain fatty acids: arachidonic acid (AA, in the case of LA) and EPA and DHA (in the case of ALA). High LA levels can crowd out the ALA and make it so that it can’t make the all-important EPA and DHA.
You can directly impact the amount of omega-3s and omega-6s in your tissues by changing your diet.https://pubmed.ncbi.nlm.nih.gov/16387724/‘>34
Although some research suggests that the high ratio of omega-6 to omega-3 in modern diets puts people at risk for developing certain diseases such as heart disease and cancers,https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5093368/‘>36 Depending on whom you ask, modern diets may have a ratio of 1:10, 1:16, 1:20, or more!
I used to bang the drum about hitting the right omega-3:omega-6 ratio in your daily diet. In recent years I’ve backed off that stance somewhat. I still think modern diets like SAD are way too high in omega-6s, but the answer isn’t to pile on heaping servings of omega-3s to balance it and “correct” the ratio. The solution is to reduce consumption of omega-6s (mostly from refined seed and vegetable oils, and products containing those oils) while getting adequate omega-3s.
Should I Supplement With Fish Oil?
It is certainly possible to be deficient in omega-3s. Clinical deficiencies usually manifest as scaly rashes. Severe omega-3 deficiencies are rare in most parts of the world, though. Subclinical low omega-3 levels may manifest as brittle nails and hair, poor sleep, or mood disturbances.
Despite a mountain of evidence that omega-3s are essential for health, there is still no clear guidance about who exactly should supplement and how much. It seems to me that the best practice, and one I follow myself is: aim to get omega-3s from food, and supplement wisely as needed. In practice, this means I select grass-fed meat when I can, and I eat pastured eggs most days, and I eat a couple servings of small-oily fish every week. I take an omega-3 supplement most days, but I’ll skip that on the days when I eat fatty fish. Plus, I eat a lot of ALA-containing vegetables.
The other thing I do, of course, is limit my omega-6 consumption by avoiding refined seed and vegetable oils. I’m not overly concerned with omega-6s found in nuts, which I don’t eat in huge quantities anyway, or other whole foods.