Which Omega Polyunsaturated Essential Fatty Acid Supplement Should I Take?
Fish oil (or omega-3 polyunsaturated fatty acids) is a bit of a rarity in the world of diet supplements...there is actually a lot of solid evidence to show that it does you good.
Of course nothing is certain, the benefits of nutrients in humans are notoriously difficult to pinpoint and nutritionists are constantly changing their minds about the goodness (or badness) of specific foods. However, I reckon the evidence supporting omega-3 PUFAs is pretty solid right now, and unless there is a major reversal in scientific thinking, this is the one supplement I do actually take.
Which doesn't mean to say that all essential fatty acid supplements are good. In fact some of them are downright bad for you. But first lets clarify all the terminology that surrounds fatty acid supplements.
Essential, Omega-3, Omega-6, Polyunsaturated...What does All of This Mean?
- Essential: Calling a nutrient essential sure sounds impressive. But in scientific studies the word has a very specific meaning: it can't be synthesised by our bodies and has to be consumed in the diet. However, just because a nutrient isn't essential (our bodies can synthesise it) doesn't mean we don't benefit from having it in the diet. And just because a nutrient is essential doesn't mean we will benefit by taking a supplement (if it's already present in abundance in the food we eat).
- Polyunsaturated: Saturated, monounsaturated and polyunsaturated all refer to bonds between carbon atoms in the chain. If there are no double bonds the fatty acid is saturated (with hydrogen atoms). One double bond and the fatty acid is monounsaturated, several double bonds and the fatty acid is polyunsaturated.
- Omega-3 etc: Omega refers to the last carbon atom in the chain (omega being the last letter in the Greek alphabet). The number refers to the position of the first double bond from the omega carbon.
Linseed, Fish and Vegetable Oils, What are the Differences?
You might be surprised to know that there are only two essential fatty acids. One is the short omega-3 alpha linoleic acid (ALA), found is the oils of certain seeds and nuts, for example linseed oil.The second is the omega-6 linoleic acid, found in most vegetable oils, for example sunflower oil. Both are polyunsaturated fatty acids (henceforth known as PUFAs)
Are you surprised not to see fish oil in that list? Fish oils are rich in longer chains omega-3 PUFAs, EPA and DHA (eicosapentaenoic acid and docosahexaenoic acid, if you insist).
This is because EPA and DHA can be synthesised in the human body from ALA. So they aren't essential. However, they, especially DHA, are the omega-3 PUFAs with the most potent anti-inflammatory actions and other benefits, such as protection against heart disease and possibly protection against dementia and diseases such as depression.
In fact doctors recommend that you eat at least two portions of oily fish a week to prevent heart disease, rather than eating seeds rich in the essential alpha-linoleic acid. Sure if you eat a lot of flax seeds, you would probably raise your levels of EPA and DHA, which can be synthesised for alpha linoleic acid. But you might as well just get the final products that are good for you.
Why Take Fish Oil Supplements?
Most nutritionists would suggest that it is much better, and often cheaper to eat the real food rather than the supplements. However, in the case of fish oil I can see the point of swallowing a pill.
Because of the contamination of the marine environment eating fish is no longer a simple decision for your health. The contaminants, such as mercury, tend to to accumulate in muscle rather than fat, so fish oil supplements are generally considered to be safe.
Also fish such as salmon is really expensive now! This is one case when buying a supplement might be cheaper than buying the real food.
If you are already eating at least two portions of oily fish a week, and you source them carefully to ensure the lack of contamination, you are probably already doing fine. If not, then a fish oil supplement could do your health a lot of good.
Avoid the Omega 3-6-9 Supplements Like the Plague!
However not all supplements are good. The ones to avoid are the 'full' omega-3-6-9 supplements. These contain both omega-3, omega-6 and omega-9 fatty acids.
At first glance these look like a really good deal. You get all the important PUFAs, plus the omega-9 oleic acid, the fatty acid found in olive oil, which might be responsible for the heart benefits of the Mediterranean diet.
But you definitely don't want to be taking a supplement that contains omega-6 PUFAs. Yes the omega-6 linoleic acid is essential, and it is important for health. However, if you use vegetable oils in your diet, you are already getting plenty of linoleic acid. And too much is bad for you!
In fact, if you read the label of the omega-3,6,9 supplements,you will probably see they contain sunflower oil to provide you with the omega-6. Really? Do you need to buy your sunflower oil in little soft gels as a supplement? I bet you have a large bottle of the stuff (or another vegetable oil) in your cupboard.
But it is not just a waste. It is positively bad for you. This is because the ratio in which you take your omega-3 and omega-6 PUFAs is really important.
The fatty acids are used in parallel metabolic pathways to produce signalling molecules such as eicosanoids which modify brain function or the immune system. The pathways sometimes use the same enzymes. If there is too much omega-6 PUFAs in your diet, they will outcompete the omega-3s, which will not be metabolised.
What is more, the eicosanoids produced form the two types of PUFAs often have opposing functions. For example omega-6 fatty acids end up as signalling molecules that promote inflammation. Omega-3s in contrast have an anti-inflammatory action. You need the correct balance between the two types for a correctly functioning immune system.
It is thought that man evolved to eat a diet with equal amounts of the two types of fatty acids. Nutritionists think a ratio of up to 4:1 omega-6 to omega-3 is healthy. In the modern diet, rich in vegetable oils, but poor in omega-3 fatty acids, that ratio could be as high as 20:1.
The last thing you want to do is to tip the balance even further by taking supplements with omega-6 fatty acids.
You might notice that a lot of these omega 3-6-9 supplements will claim that they provide you with 'exactly the right balance of omega-3 and omega-6 fatty acids'. That might well be true.....if your diet was completely free of PUFAs. That is highly unlikely!
If you use normal vegetable oils in your cooking, you are already probably getting an excess of omega-6 fatty acids. Taking a combined -3 and -6 supplement will just add to your problems.
What about Omega-9 Fatty Acids
The omega-9 fatty acid of interest is the mono-unsaturated oleic acid. This is the fatty acid found in large quantities in olive oil.
Studies suggest that it has a variety of benefits, mainly for the heart, it lowers blood pressure and bad cholesterol. In fact it is often credited with the benefits of the 'Mediterranean diet'.
All this makes it a very desirable addition, although one must be cautious about claiming that any particular nutrient is responsible for the benefits seen in a particular population. The people of the Mediterranean also consume large amounts of vegetables, less processed foods, etc.
But here's the thing. Why not just get some lovely extra virgin olive oil and incorporate it into your food? It can be used in salad dressings, dips etc. This is a much more pleasant way of getting your oleic acid than in a pill. Another food that is particularly rich in omega-9 is avocado.
There is some evidence that some of the health benefits of olive oil are due to the phenolic fraction, which contains antioxidants and other phytochemicals, rather than the lipid fraction. Similarly avocados come loaded with nutrients other than oleic acid.
The best strategy, in my opinion is to get the omega-3 PUFAs from fish oil supplements, the omega-9 oleic acid from olive oil and other natural sources, and try to limit consumption of vegetable oils, which are rich in omega-6 PUFAs.
Is Krill Oil Better than Fish Oil?
The 'new' kid on the block in omega-3 supplements is krill oil, as opposed to fish oil. The theory is that the EPA and HDA in krill oil have a higher bioavailability than in fish oil, so you get more of the omega-3 goodness into your blood.
Krill are tiny crustaceans (and chances are the krill in the supplement were sourced from 'pristine Antarctic waters'. The krill feed on the algae that produce EPA and HDA (here's a fun factoid, fish and krill also can't synthesise polyunsaturated fatty acids, only plants can perform that particular feat of metabolism. But krill eat the algae that synthesise the PUFAs, and the fish eat the krill, and the fatty acids get concentrated in their fat).
The difference between fish oil and krill oil comes from the different chemical forms in which they are present. If you get your fatty acids from eating fish, you will be consuming triglycerides. However, most fish oil supplements have the fatty acids in the form of ethyl esters. Krill oil, on the other hand has EPA and HDA in the form of phospholipids. Phospholipids are unique in that they have a hydrophilic (water-loving) and a hydrophobic (water-hating) end, and they can actually mix in water. The other forms can't. It can be expected that phospholipids will be easier to absorb.
Several human studies have tried to address this question but their results are far from conclusive. One randomised crossover (i.e properly controlled) study compared the absorption of equal doses of omega-3 fatty acids consumed as phospholipids, rTAG or ethyl esters. The scientists did see a higher level of EPA and DHA in the plasma in the group that took krill oil, but the results were not statistically significant. The study only looked at a short term indicator of omega-3 levels, rather than the long term incorporation into cell membranes.
Another possible benefit of taking krill oil is that it also contains astaxanthin, a powerful antioxidant.
I think the current evidence shows that krill oil might be a better supplement to take, but the jury is still out. Krill oil supplements tend to be more expensive than fish oil supplements,