My latest article on the International Aquafeed magazine,
March/April 2016 issue.
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There is an increasing number of
papers and reports suggesting that the nutritional value of whole fish is
higher than the one of fish oil extracts. This is a rather interesting area for
aquaculture and pharmaceutical industries, since many neutraceutical and
pharmaceutical products, claiming that they are good sources of omega-3 and
omega-6 fatty acids, are in fact extracts. Are these products really efficient
in protecting us against the onset of cardiovascular diseases (CVDs)?
Given that “theory guides,
experiment decides”, we decided to compare head to head a whole fish to an oil
extract. We chose sardines and cod liver oil. So the aim of our study was to compare
the biological activities of polar lipids of sardine fillets and cod liver oil
against atherogenesis. The total polar lipids of these two sources were
extracted and fractionated by TLC and these fractions were assessed for their
ability to inhibit the platelet-activating-factor (PAF)-induced platelet
aggregation (PAF-antagonists) or to induce platelet aggregation (PAF-agonists),
since PAF plays a crucial role in the initiation and development of
atherosclerosis.
We chose to
focus on the polar lipids since previous studies have underlined that the antithrombotic
properties of foodstuffs are mainly attributed to polar lipid
micro-constituents. We found that sardine fillet polar lipids induced platelet
aggregation, while the polar lipids of cod liver oil had a bimodal effect on
platelets. Overall, sardine polar lipid fractions showed stronger in vitro antithrombotic activities than the cod liver
oil ones. It could be thus suggested that for the prevention of CVDs, the
nutritional value of whole sardines is rather higher than the one of cod liver
oil.
It should be
also highlighted that sardines lipids were found to consist of about 58% polar
lipids as opposed to cod liver oil that contained only 1% of polar lipids. This
data suggests that in the manufacturing process of cod liver oil as it is
carried out today by leading pharmaceutical manufacturers, the polar lipids of
oils are not extracted and this has rather important negative effect on the
nutritional value of the final extract in relation to the prevention of CVDs.
We would suggest that the extraction and purification industrial processes
should be re-evaluated with the view to obtain a final extract richer in polar
lipids.
Further
reading
Assessment
of the in Vitro Antithrombotic Properties of
Sardine (Sardina pilchardus) Fillet Lipids and
Cod Liver Oil. Fishes 2016, 1(1),
1-15; doi:10.3390/fishes1010001
Ioannis
Zabetakis
Lecturer
on Food Lipids, Univ. of Limerick, Ireland
@yanzabet