Published last week in the Canadian Medical Association Journal, the study predicts the collapse of all commercially exploited fish stocks by around 2050.
According to the authors led by David Jenkins, a medical scientist, the health benefits of omega-3 are insufficiently substantiated to justify the scale of promotion the fish-derived lipids are receiving. These “overdramatized” health benefits are putting pressure on fish stocks, they claim.
“Our concern is that fish stocks are under extreme pressure globally and that studies are still urgently required to define precisely who will benefit from fish oil,” said Jenkins, a doctor at St Michael’s Hospital and a professor at the University of Toronto Faculty of Medicine’s Department of Nutritional Sciences.
Health benefits – where’s the proof?
Omega-3, particularly the longer chain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been linked to numerous health benefits, including heart health and mental health.
However, according to the researchers, the science is inconclusive and should not be used to promote the consumption of additional omega-3.
“The evidence for the comprehensive benefits of increased fish oil consumption is not as clear-cut as protagonists suggest […] Insufficient attention has been paid to individual studies and meta-analyses that fail to establish a benefit to health of omega-3 fatty acids,” they state.
Systematic meta-analyses of studies examining omega-3 benefits are indeed lacking. However, this is primarily a result of the constraints of study methodologies rather than a lack in conclusive findings of the benefits of omega-3s. Results can often not be compared and confirmed through systematic reviews or meta-analyses because the studies completed to date are too differing – conducted in different populations and using different measures.
However, although there is a general consensus that more science is needed, the studies that have been published to date provide a strong body of evidence – particularly for the heart health benefits of omega-3 – and this has been recognized internationally.
“There have been 16 international organisations that have made recommendations (for a daily intake of omega-3 EPA and DHA) based on scientific evidence in the last 20 years. Their average recommendation is 560mg,” said Dr Alex Richardson, a leading omega-3 researcher at the University of Oxford, UK, and director of Food and Behaviour Research (FAB), a UK-based charity.
According to Robert Orr, president and CEO of leading omega-3 supplier Ocean Nutrition, “the real misunderstanding is how important these EPA and DHA omega-3s are to the diet”.
“We have a massive dietary deficiency going on in the western world of EPA and DHA, and neither the regulators nor the food manufacturers nor the consumers fully appreciate the level of this dietary deficiency and it impact on health,” he told NutraIngredients-USA.com last year.
According to the new paper, entitled ‘Are dietary recommendations for the use of fish oils sustainable?’, insufficient attention has been paid to the potential environmental impact of increased fish consumption.
The researchers claim there is now “little doubt about the gravity of the fisheries crisis”, adding that fish farming is not likely to solve the problem because wild fish are needed to feed the farmed fish.
However, according to the Global Organization for EPA and DHA (GOED), an omega-3 trade association, omega-3 production is not a major contributor to the depletion of fish stocks.
Only around 6-10 percent of the total 1m tons crude fish oil produced per year is refined to produce omega-3 for human consumption, the group told NutraIngredients-USA.com. The figure from the International Fishmeal and Fish oil Organisation (IFFO) is even smaller, placing human consumption at less than 3 percent.
The study suggests that alternative sources of omega-3 should be promoted in order to ease the pressure on fish stocks.
These include algal-sourced DHA – which is currently produced by Martek BioSciences – as well as shorter-chain alpha-linolenic acid (ALA), derived from plant sources such as flaxseed.
Additionally, some of the leading agricultural firms – including Monsanto, DuPont and BASF – are advancing with work on obtaining the longer chain omega-3 from plants via genetic engineering.
“Until renewable sources of long-chain omega-3 fatty acids – derived from plant, algae, yeast, or other unicellular organisms – become more generally available, it would seem responsible to refrain from advocating to people in developed countries that they increase their intake of long-chain omega-3 fatty acids through fish consumption,” write the researchers.
Source: Canadian Medical Association Journal, March 17, 2009 Are dietary recommendations for the use of fish oils sustainable?Authors: David J.A. Jenkins MD DSc, John L. Sievenpiper MD PhD, Daniel Pauly Dr rer nat, Ussif Rashid Sumaila Dr Polit, Cyril W.C. Kendall PhD, Farley M. Mowat OC DLittDOI: 10.1503/cmaj.081274