A study on fish oil effect in rats is generating controversy. (Photo: 6th Happiness/CC BY-SA 3.0/Marco Almbauer/CC BY-SA 4.0)

Does oxidized fish oil pose health risks?

NEW ZEALAND
Monday, July 25, 2016, 09:10 (GMT + 9)

There is no evidence of a food safety risk associated with fish oil supplements currently on the New Zealand market, according to the Ministry for Primary Industries (MPI) and the Ministry of Health.

This statement was made in response to a new scientific study performed in the country stating that it has found a third of pups born to rats fed high doses of very rancid fish oil during pregnancy did not survive beyond two days.

Researchers at the Auckland University-based Liggins Institute who investigated the health effects of "off" fish oil concluded that giving pregnant rats the unoxidised fish oil did not increase mortality rates in their babies, indicating that the lethal effect on newborns came from the chemicals that omega-3 fatty acids break down into during oxidation, New Zealand Herald reported.

These researchers discovered that so many supplements were oxidised that they decided to focus on the health effects of oxidised fish oil during and after pregnancy.

“Pregnancy was a critical period when considering the safety of medications, and the same should apply to dietary supplements. Chemicals that may be harmless to mothers could potentially disrupt developmental processes in the womb," pointed out Liggins research fellow Dr Ben Albert.

However, the scientist explained that the results of this study could not be directly applied to humans and that in future studies, they hope to examine what happens in pregnant rats when you vary how oxidised the fish oil is, and to understand exactly how the oxidised fish oil harms the baby rats.

It is calculated that up to one in five New Zealand women take fish oil supplements during pregnancy, according to the latest estimate.

"While some women take fish oil during pregnancy to try to improve the development of their child's brain, there's no convincing evidence that this helps," Albert said.

Responding to the new study, Professor Murray Skeaff of Otago University doubted there would be any relevance to the health of pregnant women who take fish oil supplements, "but curiosity demands an attempt to answer the question," he admitted.

“The high mortality rate amongst pups born to rat mothers fed the oxidised oils proved that one or more compounds were produced in the fish oil during oxidation that were toxic to the rat,” he said.

Meanwhile, Dr Peter Nichols, a science advisor at the Omega-3 Centre and senior principal research scientist at Australia's CSIRO, said that following the 2015 study, the Australian Therapeutic Goods Administration performed follow-up analyses and all tested oils were not oxidised and omega-3 content met label claims.

"The new paper uses heavily oxidised oil that the New Zealand authors prepared. As Australian and New Zealand fish oils are not heavily oxidised, the study is seen as not relevant,” he claimed.

On the other hand, MPI Manager Food Science and Risk Assessment Jenny Reid believes the recently published Liggins Institute study that gave highly oxidised fish oil supplements to pregnant rats does not identify a risk to pregnant women.

"The fish oil that was given to the pregnant rats in the Liggins Institute’s study was artificially oxidised to an extremely high level, far higher than that found in fish oil supplements currently on the market. It is extremely unlikely that oxidisation of any product on the New Zealand market containing unsaturated fats would reach these levels," Reid pointed out.

Meanwhile, Ministry of Health’s Acting Director of Public Health Dr Stewart Jessamine stressed his advice to pregnant women is, and always has been, to eat a healthy, well-balanced diet and where practical to get essential nutrients from foods, not supplements.

Related article:

- Concern about discrepancy in omega-3 capsule labels

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