Q. If echium oil contains short-chain fatty acids that need to be converted to EPA and DHA, but algae oil contains these pre-formed, then surely algae oil is superior to echium oil?

A. Whilst this would seem to be the case, this is not necessarily true. We explain here…

Firstly, what is algae oil? Fish, just like humans, are unable to manufacture their own omega-3 fatty acids and have to consume them through the diet.  The predominant source of long-chain omega-3 for fish is algae.  This has led to the development of omega-3 supplements that are therefore suitable for both vegetarians and vegans, sourcing them directly from algae and bypassing the fish.  These supplements are in triglyceride form, however, and, unlike omega-3 derived from fish oils, tend to be predominantly or entirely DHA.

Relying entirely on algae oil as a source of long-chain omega-3 may not be ideal.  Triglyceride is a form of fat, and its structure  is the same as the  majority of dietary fat that is consumed.  A triglyceride molecule is simply 3 fatty acids joined by a glycerol backbone.  Different fatty acids attach to the glycerol backbone at sites termed sn-1, sn-2 and sn-3, and can be a mixture of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids.  The site of attachment is important to the overall bioavailability of any fatty acid.

So what does this mean?

In algae oil supplements, DHA is predominantly localised at the sn-2 position of the triglyceride (TAG), whereas attachment of any EPA at each site is more random (not all algae oils contain EPA).  The position of different fatty acids within triglycerides is significant because triglycerides are too big to be absorbed and have to be modified first.  Enzymes cut the fatty acids located at the sn-1 and sn-3 sites, leaving the fatty acid at the sn-2 site still attached to the glycerol molecules, which is now termed a monoglycerol.  Monoglycerols can now move freely into the cells of the gut wall, where they are reformed again as triglycerides.  However, the fatty acids that are used to reform the triglyceride are not the original fatty acids in the supplement.   Fatty acids within the cell will be from a variety of different dietary sources and will be a mix of saturated fat, mono, and polyunsaturated fat.

Supplementing with pure or predominantly DHA may therefore lead to exclusive accumulation of this omega-3 fatty acid; high-DHA supplements may therefore have consequences. For example, while DHA is important in the structure of neuronal membranes and EPA plays little or no structural role in the brain, it is essential for the regulation of brain function via its eicosanoid derivatives, such as prostaglandins, leukotrienes and thromboxanes.

Also, DHA levels tend to plateau, so increasing DHA intake may be fruitless, as these levels remain relatively stable.  In contrast, EPA has a constant turnover, the body’s needs for which can increase  in certain conditions, such as where there is inflammation.