What is omega-3?
Omega-3 is a family of essential fatty acids important in a host of biological functions. Omega-3 is the parent molecule which differentiates into alpha-linolenic acid (ALA) Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA). These are the active fatty acids that affect body tissues in various ways, and protect against inflammation. ALA is found in plants, nuts and seeds whereas EPA and DHA are commonly in both plant and animal foods, most notably in deep sea fish like mackerel or salmon.
Omega-3 is essential, meaning we need to obtain it from the food we eat because our body doesn’t produce it endogenously. Humans and all mammals can’t make ALA, EPA or DHA on their own. However, we can synthesise EPA and DHA from ALA during a process known as desaturation and elongation. Here, more carbon bonds are added making it more bioavailable and ready for use in the body (see below flow chart).
These fats are known as unsaturated fatty acids, which is a chemical term used to describe the structure of each acid compound. Unsaturated fats are highly volatile and susceptible to oxidation and going rancid if exposed to oxygen, heat and light.
Can I get enough omega-3 from plant sources?
Wild salmon, oysters, tuna and trout are by far, per gram, among the richest sources of EPA and DHA, which are the readily bioavailable forms of omega-3. Leafy green plant foods, nuts and seeds are rich in the parent compound ALA, and should be included as part of a balanced diet. However, the digestive system needs to work to convert ALA into EPA and DHA and it’s not a very efficient process. Furthermore, you’d need to eat grams or even kilos of nuts or seeds to match the same omega 3 quantity in just a single gram of sardines or salmon. So, it's for this reason that I generally recommend a combination of both plant and animal sources of essential fatty acids to ensure you’re meeting your individual requirements and can support your immune and growth needs.
Image credit: Linus Pauling Institute, Oregon State University
Why is omega-3 so good?
Simply put, foods high in fat are protective. They insulate and protect cells, nerves and tissues from ageing and support cellular function. The research is solid, and I came across a very recent review paper discussing it all.
A 2021 meta-analysis published in Nature summarised the results of all the available cohort studies which examined the relationship between omega-3 fatty acids and the risk for all-cause mortality.
Over a median time period of 16 years follow-up, more than 15000 deaths occurred among the 42266 participants involved in these studies. The results from this meta-analysis showed that the overall risk for death from cardiovascular disease and cancer as well as a range of other lifestyle-induced conditions was significantly lower (up to 18%) in omega-3 groups. The authors concluded that higher circulating levels of omega-3 was associated with a reduced risk of premature death.
Omega 3 fats are:
Cell membrane structure and signalling
At a basic biological level, everything in the body is comprised of cells and every part of our physiology depends on the activity of various chemicals moving in and out of these cells. So already, it’s easy to see how important it is to maintain our cell function. And this is all cells, including, skin, immune, brain, liver, blood cells and the rest.
Essential fatty acids form an important structural component of all cell membranes. They combine with a phospholipid layer of the cell wall and affect almost all the functions of that cell. This includes permeability, cell-signalling, fluidity and enzyme activity. How well a particular cell can communicate with other cells, bacteria or the nervous system will determine our overall health.
DHA is selectively incorporated into the retina cells of the eye and corresponding neuronal cells in the brain that interprets vision. DHA uptake is strongly increased in unborn babies, especially during the periods of brain and eye development, making omega-3 a very important nutrient for expectant mother’s to include in their daily diet.
And in general, omega 3 fats are essential to neuronal growth, synapse formation and for neurotransmitter function.
Various food sources of omega-3 (ALA, EPA & DHA):
- Marine algae & phytoplankton
- Salmon, oysters, crab, tuna, herring, mackerel, sardines
- Sunflower seeds, pine nuts, brazil nuts
- Walnuts, chia seeds, flaxseeds
Top 3 omega-3 nuts and seeds
Wild caught fish and seafood are the best and most bioavailable food sources of omega-3. True. However if you’re vegetarian or just want to maximise your plant foods - walnuts, flaxseeds and chia seeds are it. All nuts and seeds have a mixture of different fatty acid types, as well as other essential vitamins and minerals, so of course, enjoy them all!
The majority of nuts actually have a dominance of omega-6 fatty acids compared to omega-3. So for the purposes of boosting your omega-3 specifically, I recommend swapping out your favourite nuts and replacing them with seeds from time to time.
Put two walnuts together and you’ve got an almost identical shape and structure of the human brain (for more on this see our article on The Benefits of Walnuts). I’m thinking it's a clue from nature letting us know walnuts are good for brain and nervous system health. And it turns out much of the research supports this.
Walnuts are very high in protein, boasting around 7g per tablespoon, which already makes them great for neurotransmitter and brain health. Walnuts also have the highest amount of omega-3 (ALA), and together with their high polyphenol content, they have well-proved health benefits.
A 2018 meta-analysis including over 1000 participants saw diets enriched with walnuts improved cognition, reduced systemic inflammation, reduced weight and improved heart health. A study from Spain demonstrated that 15g of walnuts as part of a mixed nuts diet improved memory and brain function, when compared to a group consuming a low fat diet. The authors noted that ALA from walnuts is also associated with lower rates of cardiovascular events, such as arrhythmia and heart attacks.
I love flaxseeds, they’re tiny, they can go in and on most dishes and they’re incredibly high in alpha-linolenic acid. They’re also resistant to oxidation due to their unique antioxidant content. The SDG polyphenol found in flaxseeds protects omega-3 from excessive heat and light degradation. This means flaxseeds retain their anti-inflammatory, cardioprotective and neuroprotective properties.
If you want to really boost your plant-based omega 3, try this on for size. One study reported that a high-dose of 50g of flaxseeds a day for 4 weeks saw a significant increase in blood levels of omega-3 and lower LDL cholesterol in a group of healthy participants. If that seems a bit extreme, just a tablespoon per day will give a low but sustained increase to your omega-3 which will still have a lot of health benefits. Enjoy!
With a slightly higher omega-3 content per gram than flaxseeds, I love the humble chia seed for its ALA content and overall versatility. As the most commonly purported benefit of omega-3 is that it’s an anti-inflammatory compound, it’s good to see how the research stacks up in support of foods containing omega-3 in reducing inflammatory conditions. These are typically metabolic conditions, like heart disease, diabetes and cancer.
A 2021 study showed that consuming 40g of chia seeds per day for 12 weeks resulted in lower blood pressure in a group of diabetic participants. Another study published in the journal Nutrition, Metabolism, and Cardiovascular Diseases, confirmed that 30g of chia seeds per day aided a feeling of fullness and supported weight loss in a group of diabetic participants. Not only did the participants lose weight and have stable blood glucose levels at the 6-month mark, they also had lower inflammatory markers. Chia seeds are therefore a protective functional food in the prevention and management of obesity and diabetes (more about Chia Seeds here).
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