The new study, funded by GOED (the global organization for EPA and DHA omega-3 fatty acids), was published in Foods magazine last week. Among the authors were Gerard Bannenberg, PhD, director of compliance and scientific public relations at GOED, and Adam Ismail from KD Pharma, the former managing director of GOED. Experts from the University of California Davis, the University of Montpellier in France and the Université Catholique de Louvain in Brussels also took part.
The 2016 study found toxic effects for highly oxidized hoki liver oil
The study was carried out in response to a paper published in 2016 American Journal of PhysiologyThis used a very rancid oil from the livers of Hoki, a cod-like fish also known as blue grenadier or blue hake. The species is the basis of a commercial fishery in New Zealand. This study found that when fed to pregnant rats, the oil caused them to abort their unborn pups.
The study was criticized at the time for using a test material that was not an oil on the market that was sold as a food ingredient. The test material was prepared by blowing oxygen through the Hoki liver oil under a fluorescent light at room temperature for 30 days. In addition, the researchers opted for an oil that had no antioxidants added to delay spoilage. This is a standard manufacturing practice in the nutritional supplement industry. Such an oil would be highly unpleasant in terms of both its appearance and its foul smell and would thus present itself as obviously spoiled. A useful analog would be to leave loose oil (not encapsulated in capsules) in a bowl in the sun for a month, but the testing method used in the earlier study went even beyond that.
Despite this criticism, GOED (the Global Organization for EPA and DHA Omega-3 Fatty Acids) decided to further investigate the oxidation products identified in the 2016 study. The main problematic oxidation products have been identified as isoprostanoids and oxysterols, which the authors say have not received much attention from researchers.
Compare hoki with anchovies
The aim of the GOED study was to compare the oxidation process between a Hoki liver oil and an anchovy oil, which represents the vast majority of the omega-3 products made from fish oil on the market. For both oils, the researchers simulated the extreme oxidation conditions of the 2016 study as closely as possible. In addition, the researchers tried to compare this condition to a more relevant oxidation process, in which samples of both oils are exposed to heat and air in the dark. This would more closely mimic what could happen to an oil that may have been on the shelf long past its due date and not properly stored and handled.
The GOED paper found that the initial parameters of the two oils, although both are technically “omega-3” products, are significantly different. The anchovy oil was a standard refined MEG3 triglyceride oil supplied by DSM. In contrast, hoki oil contains a number of additional ingredients, including cholesterol.
“The analysis over time of the chemical composition changes of minimally refined, antioxidant-free Hoki liver oil under harsh oxidative conditions has confirmed the significant overoxidation of the oil. Extending the study to a different type of oxidation condition, as well as the use of a more commonly used and antioxidant-stabilized refined anchovy oil, showed that different oils contain and develop different patterns of oxidation products and that the presence of added antioxidants significantly delays oxidation, ”the authors concluded .
“It is important to emphasize that fish oils and other EPA / DHA omega-3 products are never exposed to the harshness of the experimental oxidation conditions used in this study under production and retail conditions,” the authors continued.
The 2016 condition has been replicated to get the base values
Bannenberg said the present study attempted to replicate the 2016 oxidation conditions in order to get a baseline comparison between the response of the two oils to these inputs, not because the condition was a realistic possibility for finished products.
“The conditions associated with the oil in the study by Albert et al. (The 2016 study), which we replicated in our study, were awarded to consistently bubbling with pure oxygen gas and exposure to light for a whole month. This is such a harsh condition that it will never happen to an oil that is polyunsaturated fat rich in the real world, much less when it is encapsulated and packaged, ”he told NutraIngredients-USA.
“In the study by Albert and colleagues, pregnant rats were given very high doses which, if allometrically scaled to adult humans, would consist of an equivalent daily dose of about 45 ml of fish oil. That’s roughly 10 to 100 times what a person would take in supplement form. We are not concerned about the natural levels of some isoprostanoids, oxysterols, and other oxidation products that may be found in properly manufactured fish oils used in dietary supplements of acceptable oxidative quality and taken in the doses normally taken by humans. Our study showed low levels of specific isoprostanoids and oxysterols in fish oils, but some of them increase significantly during the extremely harsh oxidizing conditions. It is possible that the high levels of these oxidation products were responsible for the in the study by Albert et al. Observed perinatal toxicity was responsible, and new studies can now be done to address this idea, ”he added.
There is essentially no risk for finished goods
Bannenberg noted that many studies of off-the-shelf fish oils in the US, UK, Australia, and elsewhere have shown that these oils are by and large of good quality from an oxidation standpoint. While bringing such oils to an extreme state of oxidation in the laboratory raises some valid questions for further research, it does not raise any alarm for consumers, he said.
“The risk of consumers buying a dietary supplement with a rancid oil, if it means a highly oxidized product, is very small if it is not missing,” Bannenberg concluded.
DOI: 10.3390 / Foods9101501
Chemical composition changes in over-oxidized fish oils
Authors: Phung AS et al.