[R.B.]

Hi Andi

I love your positive outlook and smiley posts.

Both fish oils and krill oils are high in Omega 3. The amount of long chain Omega 3 also called EPA and DHA per 1gram (1000mg) of oil depends on the marine source of the oil, as well as the extraction and refining process used in the particular oil product, and varies hugely; so check the label when considering which brand to purchase.

The primary difference between fish and krill oil are the structures to which Omega 3 is attached, which affects the way and location in which it is mainly used in the body. To understand this you need to know a little about how fats are organised in different tissues.

Fat is most commonly attached to another substance most commonly in either pairs or sets of three; image toast in toast racks, the toast is the fat and the rack the binding substance. In cell membranes fats are generally found in pairs, two slices of 'toast' to a 'rack' (phospholipids). Fat in fat cells is always found in threes, three slices of toast to a rack (triglycerides).

The toast racks used in cell membranes and fat storage are different designs; and to make things more complicated whilst there is only one design of rack for fat storage there are several models used in cell membranes.

Fish oil are extracted from fish, and crustaceans like Krill, by a combination of pressure and solvents. The ratio of storage fat to membrane fat in the krill or fish body will determine the ratio of phospholipids to triglycerides.

Krill do not contain much body storage fat compared to oily fish, and so krill oil contains mainly membrane fats (phospholipids). Oily fish contain lots of storage fat so fish oil contains mainly triglycerides.

Cell membrane fat is less resistant to oxidation than storage fat, so when they process oily fish they generally remove the cell membrane fat from fish oil products because it is easier to produce a stable product with a good shelf life; so even though membranes fats were present in the fish they do not make it into fish oil.

Krill are processed into other food products, such as protein etc, which involves removing the oil, so they started at looking at ways to process and conserve the oil rich in cell membrane fats as an Omega 3 rich product, and found ways to do so. They were helped because the krill contained a powerful antioxidant that helped protect these membrane fats from oxidation. The result is Krill oil, which contains omega 3 and other fats, and is mainly in the form of fats found in the cell membrane rather than storage fats.

Once they are in the body, the fats in cell membrane form can be directly used in the structure of cell membranes. In contrast storage fats would first have to be broken down and remade into cell membrane fats. Omega 3 rich membrane based fats are important to the function of many tissues, (and particularly the brain) which is why Krill oil may have some advantages over fish oil in so far as cell membrane function goes.

Omega 3 rich storage fats have important roles in the body too. The body will also use the Omega 3 fish oil storage based fats, but in different ways, and some of the storage fats will be converted to membrane fats for use in the cell membranes.

There are still more layers to this; not all the oil you eat ends up in the same form once it has been digested. When storage fats and cell membrane fats are digested, they are stripped down to the toast rack structure with just one fat attached, and either one or two free fats. A proportion of what is digested then gets put back together again in the original structure, but a proportion is also used as building blocks for other products including storage fats. So after digestion only a proportion of the Omega 3 rich cell membrane fats from the Krill oil eaten will be available directly for use in cell membranes in the body, while in comparison storage fats that remain in the same form after digestion would need to be reprocessed and adapted before they could be used in the cell membranes.

So krill oil is a very useful supplement along with fish oil; both provide much needed Omega 3s albeit in different forms. But they are generally both ‘solvent’ extracted so may not contain the full spectrum of fats and structures that would be found in whole food. It is also important to be cautious about miracle claims for one or other, and the advantages for krill over fish oil; they are going to do slightly different things, benefits of one over the other are not as clear cut as reports would suggest, as results depend on tissues examined, dosages, form of Omega 3s, exactly what you are looking at etc. Krill oil tends to be more expensive too, but does usefully provide the fats largely in Omega 3 rich membrane form, which you will not get in fish oil (because of the way it is processed) but will get to varying extents in fish and other marine products.

So if you are going to supplement some of both would seem a reasonable strategy, and as previously identified do not loose sight of the importance of the humble plant based Omega 3 rich foods such as flax.

Natural foods have to be the best source. Some oily fish and interestingly offal etc are good sources of membranes fats; but because we feed our livestock on grain they do not have the Omega 3 levels they should, as well as potentially containing too much Omega 6; and in reality we do not tend to eat offal any more. Brain was a traditional source of membrane Omega 3s but that is off the menu on a precautionary basis due to potential uncertainties as to the origin of neurological conditions in cattle that occurred some while ago (certainly in the UK).

The best options are the marine foods themselves, which raises the issue of the sustainability of supply. . .

I hope that helps. Thank you for your kind words they are appreciated.

P.S. Look for the phospholipid and Omega 3 content on Krill oil labels because it varies a lot between products - hopefully with both a decent phospholipid and Omega 3 content a good proportion of the phospholipids will be high in Omega 3.

P.P.S. For those unable to afford Krill a good quality fish oil is still an excellent way to get Omega 3s - but as ever fish and marine products contain a much wider range of important nutrients; but not everybody has access to or can afford fish and fish oil is a much better option than a significant Omega 3 / 6 imbalance.

P.P.P.S The amount of Omega 3 that people may want to take at the outset of a dietary change to rebalance these fats in the body might sensibly be higher, but taking large quantities for years is probably not a good idea for a wide range of reasons.

P.P.P.P.S Very very very importantly it is in significant part ultimately about balance between Omega 3 and 6. It is equally important to reduce the Omega 6 intake; the amount of omega 3 needed rises with rising Omega 6. Ultimately it is simply not possible to compensate for an excess of Omega 6 even by taking excessive amounts of Omega 3.