In the previous blog, we discussed the basics of different types of fats and their functional roles in the human body.
Now we are placing a magnifying glass over the polyunsaturated fats, namely omega 3 and omega 6, to explore their unique characteristics and, more importantly, how their interaction is vital for our overall health.
Omega-3 essential fatty acids:
The three main types of omega-3 essential fatty acids are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (1) (Figure 1).
Figure 1. Breakdown of the 3 main types of omega 3 fatty acids
Sources of omega 3 come from either plants and seeds (ALA) or marine sources (EPA and DHA) (Figure 2), with most of the research showing the greatest impact on health outcomes is associated with marine sources (2,3,4).
Figure 2: Omega 3 sources
ALA is considered essential because it cannot be produced by the body and must be obtained from the diet. It is found predominantly in plants and seeds such as flaxseeds, chia seeds, hemp seeds, walnuts, and pumpkin seeds (5). ALA exerts protective coronary effects, although not as extensive as those imparted by EPA and DHA.
As seen in figure 1, ALA can be converted to EPA then to DHA, yet this conversion is very limited: less than 5% of ALA gets converted to EPA and less than 0.5% of ALA is converted to DHA (6). Therefore, if you are vegan or vegetarian, you might consider supplementation with a plant-based DHA to meet the daily needs of this nutrient.
While ALA is deemed essential, it’s really EPA and DHA that are responsible for the health benefits of omega-3 fats.
EPA is predominantly derived from marine sources, such as mackerel, salmon, herring, sardines, anchovies, microalgae, or fish oil supplements. EPA is a powerful anti-inflammatory nutrient and is also associated with optimal fetal development, immune function, weight management, cardiovascular health, and lipid metabolism (7).
Similar to EPA, DHA is derived predominantly from marine sources such as mackerel, salmon, herring, sardines, anchovies but also meat, eggs, and dairy. The effects of this fatty acid are far-reaching, however, its particular niche is brain health and optimal cognitive function. In the elderly, low levels of DHA were shown to result in multiple measures of brain dysfunction (9). DHA is also involved in supporting cardiovascular health, eye health, and cell membrane synthesis (7,8).
Deficiency in EPA and DHA has been implicated in the development of inflammatory conditions (18). Refilling your body with as little as 200-500mg of these omega 3s a day can reverse the damaging impact; mortality from heart disease was shown to reduce by an incredible 35 percent (10)!
The Australian Heart Foundation suggests consuming 2-3 serves of fish per week (this includes oily fish) (11). Our recommendation is to opt for local, wild-caught, and small fish (sardines, garfish, whiting) to minimise mercury exposure and achieve the desired omega 3 boost.
Requirements for omega 3 will also depend on omega -6 intake; the balance between the two fatty acids is of important clinical value for vitality and disease prevention.
Omega 6 essential fatty acids:
There are two major types of omega 6 fatty acids: linoleic acid (LA) and arachidonic acid (ARA), which are produced from LA.
Similar to ALA, LA is considered essential as it cannot be produced by the body. It is found naturally in cereal grains, meat, nuts, and fruit. Unfortunately, It is also present in large amounts in industrially processed and refined oils like cottonseed, canola, corn safflower, and sunflower oils (Figure 3).
Figure3: Processed oils high in omega 6 fatty acids.
This is where the problem originates.
Whereas moderate consumption of omega -6 fatty acids from whole-food sources has been associated with positive health outcomes, including cardiovascular and brain health (eg. ARA along with DHA is one of the most abundant fatty acids in the brain (12), intake of processed omega -6 fatty acids has dramatically increased the incidence of inflammatory conditions(13).
Excess LA has been shown to deplete vitamin E, lead to gut dysbiosis and inflammation as well as contribute to weight gain and liver disease (14). Excess omega -6 may also inhibit the conversion of omega-3 ALA into EPA and DHA (15). For example, one study demonstrated that an increase of LA consumption from 15g/d to 30g/d decreases ALA to DHA conversion by 40% (16).
Historically, our hunter-gatherer ancestors consumed omega-6 and omega -3 fats in a ratio of 1:1. With the advent of industrialisation, consumption of omega-6 fats increased at the expense of omega-3 fatty acids. Today, this ratio ranges from an average of 10:1 to 20:1, with as high as 25:1 in some individuals (17).
The health consequences of this shift cannot be underestimated. It is important to emphasise that, as a result of this change, inflammatory conditions, such as cardiovascular disease, obesity, metabolic syndrome, and inflammatory bowel disease, are reaching epidemic proportions (18). On the other hand, decreasing the omega 6:omega 3 ratio appears to be protective against chronic degenerative diseases (19).
Balancing omega 3 and omega 6
What can you do to modulate omega 6 intake and reach an optimal ratio between the two omegas? For most people, reducing omega-6 intake and increasing EPA/DHA intake are necessary to achieve the desired result.
- Eat real food. Prioritise naturally occurring omega-6 in nuts, seeds, pastured meat, and other whole foods. If you are consuming adequate amounts of omega-3 fatty acids, it will not be an issue. They are considered essential fatty acids, after all, so you do need some in your diet. Quality matters.
- Avoid industrial seed oils. Opt for nutrient-dense oils including olive oil, coconut oil, ghee, and other pastured animal fats.
- Eat pre-formed EPA and DHA. Consuming cold-water fatty fish is a good idea for everybody, but it’s especially important for people that have diets high in omega-6 fats.
Omega 3 and omega 6 provide a wide array of health benefits. Maintaining a ratio of omega 6: omega3 as close to 1:1 as possible is imperative for reducing inflammation and as a disease prevention strategy.
- Whitney, E., Rolfes, S., Crowe, T. and Walsh, A., 2017. Understanding nutrition. 3rd ed. pp.154-155.