Ester Osuna

You wouldn’t eat a fish out of your backyards pond if there would be tires swimming in oil puddles, wouldn’t you? Fish provides us with essential omega-3 polyunsaturated fatty acids (n-3 PUFAs), which are known for their myriad health benefits. Still, illegal, unreported and unregulated fishing remains one of the greatest threats to sustainable fisheries. Nutritional research should focus on alternative sources and approaches of delivery of the essential nutrients for optimally supplying the growing world population. Also, holistic approaches taking into account human and animal health could benefit social and environmental services.

The role of omega-3 fatty acids in human health and where to find them

The interest in omega-3 polyunsaturated fatty acids (n-3 PUFAs) their myriad health benefits did rise substantially in the past few decades. Even though there might be some controversies about their efficacy and certain benefits to human health, n-3 PUFAs are linked to cardiovascular disease, diabetes, cancer, Alzheimer’s disease, dementia, depression, visual and neurological development, and maternal and child health [1]. For this blog post in order to simplify the topic let me just state, that n-3 PUFAs are beneficial for cardiovascular and brain health throughout life: from the foetus’ health during the mother’s pregnancy, to adolescence, adulthood and aging life.

n-3 PUFAs are essential fatty acids, meaning that the human body cannot synthesize them by itself. Hence, n-3 PUFAs need to be taken up through diet. The two most active forms of n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are exclusively found in aquatic organisms. Very well-known sources of EPA and DHA are the liver of lean white fish such as cod and halibut, the body of oily fish such as mackerel, menhaden, and salmon, and the blubber of marine mammals such as seals and whales [1]. Still, the predominant producers of long-chain n-3 PUFAs such as DHA are marine algae. EPA and DHA are synthesized by phytoplankton and end up in the lipids of fish and marine mammals via the food web [1]. Available evidence indicates, that the recommended dietary requirements for n-3 PUFAs for optimal adult health and foetal and infant development is 0.3 g/d EPA+DHA, of which at least 0.2 g/d should be DHA [2]. Still, official recommendations of e.g. the US Food and Drug Administration (FDA)or the Australian and New Zealand reference values have set a “generally regarded as safe” level of 3000 mg/day of n-3 PUFAs [2]. In Western diets however, n‑3 PUFAs are generally under-consumed [3]. There are supplementation strategies in order to improve blood fatty acids levels. Rates of compliance however are generally low due to difficulties in swallowing capsules, or unfavourable aftertastes. Another potential strategy is bio-fortification, but this itself has limitations, including the problem of lipid oxidation affecting sensory characteristics and shelf-life [3]. To summarise, n-3 PUFAs have beneficial effects on human health whenever a daily-recommended intake of 0.3 g/d is met. In western diets however, n-3 PUFAs are generally under-consumed and there is still a lot of work when it comes to answering the question on how to deliver enough of the essential n-3 PUFAs for an optimal health outcome.

Overfishing and the question, whether our food system can support the recommended daily intakes of omega-3 fatty acids

In 2019, the United Nations (UN) report on the progress towards the Sustainable Development Goals (SDGs) concludes, that the fraction of world marine fish stocks that are within biologically sustainable levels declined from 90% in 1974 to 66.9% in 2015 [4]. Although a framework of international instruments has been developed addressing different aspects of fisheries management, illegal, unreported and unregulated fishing remains one of the greatest threats to sustainable fisheries. According to the UN report on the progress of the SDGs, policies and their implementations encouraging responsible use of ocean resources are still insufficient to combat the adverse effects of overfishing, growing ocean acidification due to climate change and worsening coastal eutrophication [4]. Billions of people depend directly on the oceans for their livelihood and food source, moreover also broad public health can benefit from the nutrients, such as n-3 PUFAs, the oceans produce.

We can calculate the demand of n-3 PUFAs according to the recommended daily intake of 0.3 g of n-3 PUFAs (0.3 /day x 365 x 8 billion) easily as a total of approximately 0.9 million tonnes. The more difficult part is to calculate the supply of n-3 PUFAs from the oceans. Taking into account different models, we can optimistically estimate the supply of n-3 PUFAs at just over 0.8 million tonnes [5]. After doing the math, it becomes obvious that even when calculating the n-3 PUFA supply optimistically, our planetary resources fail to cover an optimal n-3 PUFA supply to our growing world population.

Figure 1 Fish providing essential n-3 PUFAs for human health

The challenge of sustainably maintaining the quantity and quality n-3 PUFAs for human and environmental health

While restoring sustainable fish populations will benefit the economic and food security of billions of people, for optimally supplying the growing world population with adequate n-3 PUFAs nutritional research should focus on alternative sources and approaches of delivery of the essential nutrients. Nutritional recommendations and guidelines should take into account planetary resources: How can we promote the consumption of certain aliments if we are already short on them? Still, the amount of consumption is not the only challenge. How does animal health affect the quality of the food the animal is providing? We do not only need to take care of the fish stocks but also on their health, which strongly depends on the health of the oceans. One interesting and promising concept published in 2018 called One Health showed an integrated view on health of humans, animals and plants, complementing the framework of The Lancet Countdown on health and climate change [6]. One Health was defined as any added value in terms of human and animal lives saved, reduced cost and sustained social and environmental services that can be achieved by a closer cooperation of human and animal health and other disciplines which could not be achieved if the sectors worked separately [6]. In other words, maintaining our oceans clean and safe for their inhabitants benefits our own health when sustainably living from the oceans’ provided food resources.

References

1. Shahidi, F. and P. Ambigaipalan, Omega-3 Polyunsaturated Fatty Acids and Their Health Benefits. Annual Review of Food Science and Technology, 2018. 9(1): p. 345-381.
2. WHO, Interim Summary of Conclusions and Dietary Recommendations of Total Fat and Fatty Acids, in From the Joint FAO/WHO Expert Consultation an Fats and Fatty Acids in Human Nutrition, 10-14 November, 2008. 2008, WHO: Geneva.
3. Lane, K.E. and E.J. Derbyshire, Omega-3 fatty acids – A review of existing and innovative delivery methods. Critical Reviews in Food Science and Nutrition, 2018. 58(1): p. 62-69.
4. Nations, U., Special edition: progress towards the sustainable development goals. 2019.
5. Tocher, D.R., et al., Omega-3 Long-Chain Polyunsaturated Fatty Acids, EPA and DHA: Bridging the Gap between Supply and Demand. Nutrients, 2019. 11(1).
6. Zinsstag, J., et al., Climate change and One Health. FEMS Microbiology Letters, 2018. 365(11).