Omega-3 nutritional supplements need to be of good quality if they are to provide all the benefits demonstrated by scientific research. The source of the raw materials, effectiveness of the purification process, protection from oxidation, bioavailability, and concentration in active principles are all elements that inevitably dictate the quality of omega-3s.
Omega-3 fatty acids are found widely in Nature, particularly in the marine world, but it is only the marine-origin omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which play an important role in human cells. Plankton, of which there are over 4,000 recognised species, is the richest source of EPA and DHA. It is also marine life’s essential nutrient.
Fish naturally rich in omega-3
The unrefined fish oil principally used for nutritional supplements is produced from fish with a naturally high content of omega-3 polyunsaturated fatty acids, such as sardines, mackerel or anchovies.
To obtain high quality raw materials with optimal purity, fishing zones are prioritised that are free from any industrial contamination. Sardines, mackerel and anchovies are found in abundance in the cold waters of the Humboldt Current. This is a stretch of water along the Chilean and Peruvian coasts which is particularly rich in phytoplankton.
Environmental pollutants love fats
A large number of industrial pollutants are fat-soluble. They become directly absorbed into the lipids of the algae and marine creatures consumed by the oily fish that feature in our diet and which are the source of fish oils. Unpurified fish oil-based products generally have excessive levels of contaminants such as mercury, lead, PCB or dioxins.
Highly-sensitive to oxidation
Omega-3 fatty acids are highly-reactive and become easily oxidised when exposed to oxygen, light, heat and traces of metal (iron, copper).
The irreversible consequences of such oxidation include, in particular, a decrease in nutritional value, a deterioration in texture and colour and alterations in taste due to rancidity.
The most damaging consequence of fatty acid oxidation is, however, the appearance of harmful free radicals. After eliminating pollutants, preventing this oxidation is thus a key quality-related objective. Oxygen removal, protection from light, refrigeration and removal of metallic ions are among the preventative measures employed. However, they are not always possible and are frequently inadequate. Stabilisation with antioxidants is therefore required and natural-source, non-GMO tocopherols are added to the product at this stage.
Fish oil omega-3s are currently available in two forms: the natural form- triglycerides - found in fish oils, and the synthetic, chemically-produced form - ethyl ester concentrates. The term ‘natural fish oil’ indicates that no synthetic chemical has been used or added in the manufacturing process and that the omega-3 fatty acids are still in their natural triglyceride form.
There is a significant difference in bioavailability between the two forms: ethyl esters may be only half as bioavailable as the natural form.
One study comparing absorption following a single dose found that the natural, triglyceride form was three times’ better absorbed than its synthetic counterpart.
Another study examining the bioavailability of EPA and DHA found that ethyl ester forms were 40% and 48% less well absorbed respectively than natural triglyceride forms.
One reason for the ethyl ester form’s lower bioavailability may be its greater resistance to digestive enzymes. In the course of the digestive process, pancreatic lipases hydrolyse the oil in order to release the fatty acids, a preparatory stage for their subsequent absorption. Studies have shown the ethyl ester form is 10-50 times more resistant to this enzymatic process than the natural triglyceride form.
Lawson LD et al. 1988. Absorption of eicopentaenoic acid and docosahexaenoic acid from fish oil triacylglycerols or fish esthyl esters coingested with a high-fat meal. Biochem Biophys Res Commun, 31; 156(2): 960-3.
- Beckermann B et al., 1990. Comparative bioavailability of eicosapentaenoic acid and docohexaenoic acid from triglycerides, free fatty acids and ethylestersinvolunteers . Arzneimittelforschung, 40(6): 700-4.
- Yang LY et al. 1990. Lipolysis of menhaden oil triglycerols and the corresponding fatty acid alkyl esters by pancreatic lipase in vitro: a re-examination. J Lipid Res, 31(1): 137-47.