Why are omega-3 fatty acids so important?

You have probably already heard that omega-3 fatty acids are very important and that you should be including them in your diet. But why is that?

This article is the first of a series of 3 articles about omega-3:

– in this first article, I will explain you what types of omega-3 are most essential for us and their benefits

– in the second article, I will write about the conversion from the plant-based omega-3 to the other types of omega-3

– in the third article, I will write about the problem with fish sources of omega-3, several types of omega-3 supplements and their pros and cons, and what is, in my opinion after reviewing the scientific literature, the best one.

There are several types of omega-3 fatty acids, but the most relevant to humans are these four:

– eicosapentaenoic acid (EPA)

– docosahexaenoic acid (DHA)

– alpha-linolenic acid (ALA)

– stearidonic acid (SDA)

Omega-3s belong to a family of fatty acids called polyunsaturated fatty acids (PUFAs). The major families of PUFAs are the omega-6 fatty acids, with its precursor linoleic acid (LA), and the omega-3 fatty acids, with its precursor alpha-linolenic acid (ALA). As the body cannot synthesize LA and ALA, and thus must be obtained through our diets, they are called “essential fatty acids”. SDA, EPA and DHA can be synthesized from ALA, although DHA in a lower extent as I will further explain in the next article (although this depends on many factors – read the next article 🙂 ).

Humans have evolved consuming approximately equal amounts of omega-6 and omega-3 [50]. Both omega-3 and omega-6 fatty acids are important for many body functions. For instance, they are both precursors of substances involved in blood pressure regulation and inflammatory responses. However, this balance of omega-3:omega-6 has changed over the past century. In the modern western diet, omega-6 intake is much higher than omega-3 fatty acids due to the high intake of vegetable oils. And this is a problem, because the omega-3 fatty acid ALA and the omega-6 fatty acid LA compete for the same enzymes. So, if there is more omega-6, it will win the enzyme, which will inhibit the synthesis of the long-chain PUFAs EPA and DHA [51]. However, in the correct amounts, omega-6 are also essential for us. While in the current article I will highlight the benefits of omega-3s, I wanted to have this also pointed out.

EPA and DHA

EPA and DHA are present in certain microalgae in the ocean, which end up being ingested by fish. This is why fatty fishes, such as sardines and salmon, have a relatively high amount of omega-3 fatty acids. However, as you can imagine, it is also possible for us to obtain these omega-3s if we consume directly these microalgae instead of the fish (read the third article for more information on this topic).

EPA and DHA are important structural components of cell membranes and therefore, are crucial for ensuring cell function. DHA, in particular, is the main omega-3 fatty acid in the brain and retina and is crucial for brain health. For example, they can improve the symptoms of major depression [9] and mild-to-moderate depression (particularly EPA) [10, 11]. Interestingly, a study showed they can be as effective as Prozac (or fluoxetine, an antidepressant drug) in the treatment of major depression [12]! They have also been shown to reduce anxiety [13], reduce ADHD (Attention-deficit/hyperactivity disorder) symptoms [14] and improve mood swings in bipolar disorder [15, 16] and schizophrenia [17]. Also, they can improve sleep [18, 19]!

DHA, in particular, has been shown to regulate neuroinflammation [20], to slow cognitive decline in elderly individuals [21] and may be important in the prevention and also treatment (i.e., in slowing cognitive decline) of Alzheimer’s disease [22-24], but larger studies are still needed.

DHA is also crucial for promoting a healthy brain development during pregnancy and early life. Studies have shown that higher DHA levels in these periods could later lead to higher mental and academic performance [25-27]

These omega-3 fatty acids have also been shown to improve several markers of heart disease [1] (including in patients with metabolic syndrome [2]), namely reduce triglycerides levels [3, 4], reduce blood pressure [5], increase HDL (“the good cholesterol”) levels [4], reduce inflammation [6] and – improve endothelial* function [7]. However, despite these benefits on cardiovascular disease markers, there is still no convincing evidence that omega-3 supplements can really prevent heart attacks or strokes [8]. Maybe the source (foods vs fish oil supplements) matters? More studies are still needed on this, especially because the majority of studies have been conducted on fish oils. It would be interesting to know whether other forms of supplementation (see more information in our third article about omega-3 supplements) would improve the results.

*The endothelium is the inner surface of blood vessels.

In addition to all these benefits, omega-3 fatty acids have been shown to reduce inflammation [28, 29] and to be beneficial in inflammatory and autoimmune diseases [30], such as rheumatoid arthritis [31, 32] and lupus [33].

So, do all these benefits mean that you should consume fish or fish oil supplements every day?? NO!!! Please read my third article on this omega-3 topic, where I will explain you the cons of eating fish and consuming fish supplements regularly, and let you know about more sustainable and healthier alternatives.

ALA

ALA is a plant-derived omega-3 fatty acid and can be obtained from ground flax seeds, hemp seeds, chia seeds and walnuts.

ALA is the most frequent type of omega-3 in the diets of people who do not regularly consume fatty fish. ALA has been linked to many health benefits as well, including reduced risk of cardiovascular diseases, bone fracture and type 2 diabetes [34-37]. ALA also competes with LA in certain metabolic pathways and so may reduce the arachidonic acid content of cells and tissues (an omega-6 which fuels inflammation), which might be important for controlling thrombosis, inflammation, bone loss, immunosuppression and cancer [38]. There is some evidence that ALA has cardiovascular protective effects especially in populations where EPA and DHA intake is low [39]. Also interestingly, several studies have shown that ALA has an LDL-cholesterol lowering effect (popularly known as the “bad cholesterol”), and this effect seems to be even higher than the one found for EPA and DHA [38, 40, 41].

Furthermore, two important studies in patients with high blood pressure, published in the renowned journal Hypertension, reported that the consumption of 30g of milled flaxseeds per day for 6 months led to a significant reduction in systolic and diastolic blood pressure (the upper and lower values that you get when you measure blood pressure) [42, 43]. One of these studies is even entitled “Potent antihypertensive action of dietary flaxseed in hypertensive patients“! And the researchers concluded, in their own words:

” flaxseed induced one of the most potent antihypertensive effects achieved by a dietary intervention”.

The researchers found a correlation between the circulating ALA levels and both systolic and diastolic blood pressure, and also a correlation of lignan (another very important phytonutrient in flaxseeds) levels with diastolic blood pressure.

In order to increase our levels of ALA, the omega-3 rich seeds should be consumed milled rather than whole [44]. If they are not ground, these seeds will leave your body as they came in and therefore you will not profit from their health benefits. I recommend you buy the whole seeds and grind them yourself freshly, right before you eat them. This is because when the seeds are ground and exposed to air and light, they oxidize very easily. I like to soak the flax and hemp seeds overnight and then add them to my blender with some water/almond milk in the morning and eat them immediately.

Flaxseed oil is also available, however make sure that it was cold-pressed and that it had no contact with air. Furthermore, flaxseed oil should only be used in salads or cold dishes and you should never cook with it!

There are people consuming ALA-enriched margarine thinking it is a healthy food. Please don’t do that. Margarine is everything but a real food: it’s a highly processed and refined vegetable oil, full of the harmful trans-fats, which is actually really dangerous for you [45].

SDA

Stearidonic acid or SDA is much less studied than the other 3 types of omega-3, but I decided to include it also in this article because it has some interesting properties.

SDA is an intermediate in the pathway of EPA and DHA synthesis. It has been suggested that the rate of conversion from SDA to EPA and DHA is higher than the one of ALA (more on that in the next article).

Plant sources of SDA include hemp seeds and seed oil, algae, seeds from members of the Boraginaceae plant family, including borage, Echium (Viper’s bugloss) and Buglossoides (Corn gromwell) [46-48].

SDA has also been reported to inhibit cancer growth, exhibit antithrombotic activity , lower triglycerides, be beneficial for rheumatoid arthritis as well as skin conditions such as acne and skin inflammation [46, 49].

In the next article, I will go in further detail on the conversion from ALA to EPA and DHA and in the third article, I will then write about EPA and DHA sources and the pros and cons of several supplements.

Live healthy,

Ana

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