The industry body said it would contact the University of Canterbury where the researchers were working as professors, adding that it also wanted a public apology from them for the reputational damage caused.
Published in The New Zealand Medical Journal on September 20, the paper claimed that six out of the country’s top 10 best-selling fish oil products contained less EPA and DHA than the levels stated on the product labelling.
According to the study, these products contained between 48% and 89% of omega-3 fatty acids amounts stated on labels, and hence, “would unlikely confer all health benefits claimed”.
These benefits include heart health, joint, and brain health.
Only four products contained omega-3 fatty acid which were similar to the label content, the paper claimed.
In a rebuttal, the national industry organisation insisted that 90% of the products have met labelling claims.
The main point of contention appears to be with the calculation methods used.
“The paper’s researchers have made fundamental calculation errors in the way they have interpreted the omega-3 test results. The errors have resulted in completely the wrong conclusion being drawn about the label claims made by the fish oil products tested,” chairwoman of Natural Health Products NZ, Lorraine Moser, said in a statement.
Elaborating on the errors, she added that the researchers had failed to consider that the test results were expressed in one gram units, and hence should have extrapolated for larger capsule sizes.
For instance, when assessing the label claims for products with 1.5 gram capsules, the researchers did not multiply the test results by 1.5 to give an accurate result, she added.
“Correctly extrapolating the test results for each capsule size has identified that all but one of the tested products were well within acceptable tolerances related to their label claims.”
The paper did not specify when the testing of the fish oil products took place.
However, the industry body noted that it was written based on a Masters thesis completed in 2016, in which testing took place in 2015.
As such, it questioned the data’s relevance in the current context, and the ethics behind using old data.
“We would be interested to know when the testing was done for products discussed in the NZ Medical Journal paper. Was the paper referring to tests done five years ago, or was more recent testing done?
“If the test results are five years old then – regardless of the researchers’ calculation errors – we question the relevance and ethics of using such old data to draw conclusions about products sold now,” Moser said.
The industry body said the erroneous findings had damaged the country’s good name in the health supplements industry, and gave consumers a “needless” cause for concern.
It said had requested the University of Canterbury to review processes associated with the original thesis upon which this paper is based, and the paper itself.
“New Zealand’s natural health products industry has incredibly high standards in terms of product quality and ethical behaviour.
“Ensuring natural health products are safe, effective and contain what is stated on the label lies at the very heart of what we and our members do so it is incredibly frustrating to see shonky research like this not only being published, but also publicised,” Moser said.
Source: The New Zealand Medical Journal, Vol 132, No 1502
Are over-the-counter fish oil supplements safe, effective and accurate with labelling? Analysis of 10 New Zealand fish oil supplements
Authors: Julia J Rucklidge et al