The Omega Ratio

Useful Or An Unnecessary Hassle?

Over the past few decades, the official nutrition policy of several nations has recommended that people include oily fish – that’s fish like salmon, sardines, pilchards, mackerel and trout – two or three times in their weekly diets. The reason for recommending these foods is that they provide omega-3 fatty acids, a good intake of which may provide protection against some diseases. Sometimes these recommendations go further, noting that, if you don’t consume oily fish, you should consume algae or fish oil supplements. As well as this, some experts claim that it’s not just consuming omega-3s that’s important, but that we also need to consider the ratio of omega-3 to omega-6 fatty acids, meaning that we possibly should be moderating our intake of the latter.

Having to calculate our intake of nutrients, all sounds like a load of unnecessary hassle! So, we should explore the validity of these claims, as, after all, most of us just want to enjoy nutritious food without worrying about the numerical ratio of one nutrient to another. And what about non-fish eaters?

What Are Omega-3s and -6s?

There are several different classes of fats including saturated, monounsaturated and polyunsaturated fats. Polyunsaturated fatty acids (PUFAs) are those that have more than one double bond in their chemical structure. The two main types we consume in our diets are omega-3s and omega-6s (the terms refer to their structure).

As humans, we must include two fatty acids regularly in our diets. These essential fatty acids (EFAs) are linoleic acid (LA), which is an omega-6 fatty acid, and alpha-linolenic acid (ALA), an omega-3. In addition, although they can be synthesised in the body, two other omega-3s can be useful to consume as they reduce the requirement for ALA: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA can be obtained from oily fish, marine algae or supplements. If you don’t eat oily fish, you’ll have to ensure that you acquire a good intake of omega-3s from other sources – like flaxseed, chia and hemp seeds, walnuts or some seed oils – though omega-3s are present in smaller quantities in a wide range of plant and animal foods. The levels of EPA and DHA in the blood are linked to both how much we have in our diets and the efficiency of certain biological processes involving their conversion from ALA [1]. There is, however, relatively inefficient conversion, and, for this reason, if your diet doesn’t contain much EPA and DHA, you’ll need a considerably higher intake of ALA. A good level of omega-3s in the blood – especially EPA and DHA – is important due to protective effects in relation to cardiovascular disease and other conditions where inflammatory processes are involved [2]. In addition, low levels of DHA have been linked to negative neurological effects [3].

Similarly, there are two semi-essential omega-6 fatty acids: arachidonic acid (AA) and gamma-linolenic acid (GLA), and a good dietary intake of these reduces the requirement for LA.

The requirement for omega-3s has been shown to go up if a diet is higher in saturated fat, trans fats or alcohol, or if there’s a high level of insulin in the blood; these influence the function of the enzyme that converts ALA to EPA and DHA [4]. Also, diets high in omega-6s have been shown to lower the conversion of ALA to EPA and DHA. This is because ALA competes with LA, which is relatively abundant in many diets, as the same enzymes are involved in converting LA to AA [5]. This implies that a diet rich in omega-6s increases the demand for ALA in the absence of EPA and DHA and therefore the ratio of omega-3:omega-6 might also be important.

The 3 to 6 Ratio

One of the reasons that our bodies require fatty acids – both omega-3s and -6s – is because they make up the structure of cell membranes. The strength of the membrane depends on a number of factors, one of which is the degree of presence of omega-3s. The amount of omega-3s that’s taken up depends on what’s available in the blood, and, it’s been suggested, if there are too many omega-6s, the membrane becomes weaker and less resilient [6]. The greater the amount of omega-3s available relative to the amount of omega-6s the more strength-building omega-3s will be incorporated into the cell membrane. 

The inflammatory response is also relevant. Eicosanoids are signalling molecules involved in the immune response and are linked to the degree of inflammation. Omega-6 fats produce more pro-inflammatory eicosanoids and omega-3s more anti-inflammatory ones [7]. Again, omega-3s and -6s compete with one another: they share some of the enzymes involved in eicosanoids production. This means that an imbalance in the ratio of omega-3 to -6s may also lead to an imbalance in the inflammatory signalling molecules.

In order for the ideal quantity of each category of PUFA to be incorporated into cell membranes and for an optimal level of inflammation, it’s been suggested that the balance of omega-3:-6 should be no more than 1:4 (i.e. up to four times more omega-6s than -3s) [8]. It’s claimed that our hunter-gatherer ancestors, through acquiring their nutrition from a range of foods, would have had these sorts of intakes, and this is also the case for people living in remote areas today. Intakes of many modern diets, however, have led to large amounts of omega-3s being omitted and omega-6s are more prevalent, leading to typical ratios of 1:15 to 1:20 or even higher [9]. However, any advice that we should stick to a set ratio seems like too much of a simple answer to a very complex issue.

Omega Reductionism?

We humans like convenient explanations for complicated things. Unfortunately, nutrition rarely provides such simplistic descriptions: case in point, the omega ratio. For instance, the narrative provides no differentiation between particular omega-3 and omega-6 fatty acids. A higher level of LA doesn’t necessarily mean more AA is produced – which is the prerequisite of pro-inflammatory eicosanoids – and the presence of ALA provides no indication as to whether more EPA will be created or more DHA.

It’s questionable enough that people rely so much on the calorie count of their daily diets, as well as things like how many grams of protein, saturated fat and sugar is in their meal, without adding further complexity to ensure that for every four grams of omega-6 they consume they have to counterbalance with at least a gram of omega-3 – that’s going to be a challenge to keep an eye on!

Is it even worth watching? Worrying about the ratio of one set of nutrients to another strikes me as extremely reductionistic and unviable; the evolution of human dietary requirements simply didn’t require our bodies to have this level of detail. This might explain why studies investigating fish are more likely to find a positive outcome than studies investigating fish oils or individual fatty acids on their own. Could it be that there are other things present alongside the fatty acids in fish that are beneficial? One report reviewed studies around the current guidelines that recommend the consumption of either one to two servings of oily fish per week or daily fish oil supplements (around one gram of omega-3s a day) in adults. The authors claimed that “recent large-scale studies have failed to demonstrate any benefit of fish oil supplements on cardiovascular outcomes and mortality” [10]. Another study suggested that the beneficial effects of fish consumption on atherosclerosis may be via other mechanisms than merely omega-3 fats on their own [11]. Do bear in mind that, whilst omega-3s play a key role in modulating the inflammatory response to a clinically relevant level, it doesn’t mean that omega-6s have the opposite effect. Indeed, some experts feel we should be encouraging whole, unprocessed sources of both types [12].

How Much Omega-3s Should We Consume?

So what’s the answer? Simply make sure you’re consuming good sources of omega-3s. In traditional diets, this was easier. For example, in pre-intensive farming, the amounts of omega-3s in many plant foods were marginally higher and, whilst on an individual food basis, this was of low significance, through the course of a day, this led to a reasonable contribution of omega-3 intake. Always the optimist, I hope this may be something that will be addressed as Western farms move over to regenerative agricultural methods.

The nutritional quality of the fish we serve up has also changed. Take tuna, for example: the most commonly consumed type of tuna is yellowfin – what you get when you open a can or buy from your local supermarket fish counter. Tinned tuna is no longer included in official oily fish recommendations, because, it’s claimed, the canning process removes much of the omega-3s. The canning process is only part of the reason: canned tuna may have an unimpressive 0.04g omega-3s per 100g, but tuna steak isn’t much more exciting with just 0.11g. Compare this to salmon, which is around 3g. This hasn’t always been the case. Prior to commercial fish farming, free-swimming fish used to feed off plankton which, itself, fed on omega-3-rich algae, meaning that the fish were omega-3 rich. Interestingly, bluefin tuna – an expensive and rare delicacy – has considerably higher levels of omega-3s: 1.3g per 100g. [13]

Whilst the knowledge of the omega-3:-6 ratio provides interesting learnings for scientists, when it comes to providing nutritional advice, things are more nuanced. It’s far more important to simply make sure you’re consuming sufficient amounts of foods that contain omega-3s rather than unduly worrying about omega-6s. Just make sure you consume whole-oil sources that haven’t been damaged by processing.

(Article originally posted on LinkedIn on September 27, 2021)

References:
1. Davidson, M.H. (2013) ‘Omega-3 fatty acids: new insights into the pharmacology and biology of docosahexaenoic acid, docosapentaenoic acid, and eicosapentaenoic acid’, Current Opinion in Lipidology, 24(6), 467-74.
2. Yannios, T. (1999) The Heart Disease Breakthrough, New York: Wiley.
3. Horrocks, L.A. et al. (1999) ‘Health benefits of docosahexaenoic acid (DHA)’, Pharmacology Research, 40(3), 211-25.
4. Linus Pauling Institute. Oregon State University. Essential Fatty Acids. Available at:
https://lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids (Accessed: 14/09/2021).
5. Simopoulos, A.P. (2002) ‘The importance of the ratio of omega-6/omega-3 essential fatty acids’, Biomedicine & Pharmacotherapy, 56(8), 365-79, (b) Simopoulos, A.P. (2006) ‘Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases’, Biomedicine & Pharmacotherapy, 60(9), 502-7.
6. ibid (5a).
7. (a) Calder, P.C. (2010) ‘Omega-3 fatty acids and inflammatory processes’, Nutrients, 2(3), 355-74, (b) Wall, R. et al. (2010) ‘Fatty acids from fish: the anti-inflammatory potential of long-chain omega-3 fatty acids’, Nutrition Reviews, 68(5), 280-9.
8. (a) Simopoulos, A.P. (2008) ‘The omega-6/omega-3 fatty acid ratio, genetic variation, and cardiovascular disease’, Asia Pacific Journal of Clinical Nutrition, 17(Suppl1), 131-4; (b) Julia, C. et al. (2013) ‘Dietary patterns and risk of elevated C-reactive protein concentrations 12 years later’, British Journal of Nutrition, 110(4), 747-54.
9. Simopoulos, A.P. (2006) ‘Omega-6/Omega-3 Essential Fatty Acid Ratio and Chronic Disease’, Food Reviews International, 20(1), 77-90.
10. Goel, A. et al. (2018) ‘Fish, Fish Oils and Cardioprotection: Promise or Fish Tale?’, International Journal of Molecular Sciences, 19(12), 3703.
11.  Johnsen, S.H. et al. (2018) ‘Fish consumption, fish oil supplements and risk of atherosclerosis in the Tromso study’, Nutrition Journal, 17(1), 56.
12. Deckelbaum, R.J. et al. (2010) ‘Dietary n-3 and n-6 fatty acids: are there “bad” polyunsaturated fatty acids?’, Current Opinion in Clinical Nutrition & Metabolic Care, 13(2), 123-4.
13. Values from nutritics.com and nutritiondata.self.com (Accessed: 14/09/2021).