The omega-3 gap
Author: Helen Ann Hamilton, Ph.D. (BioMar Global Sustainability Specialist)
It is widely known in the aquaculture industry that omega-3 fatty acids, EPA and DHA, are critical inputs to fish farming and a large part of what makes eating fish so healthy. However, the importance of EPA/DHA for humans goes beyond general human health. EPA and DHA facilitate cognitive and neurological development during infancy and can also slow the progression of degenerative diseases later in life. This makes it critical that we have enough EPA and DHA, as human nutrition gaps can lead to widespread negative health consequences.
Humans get EPA and DHA primarily through eating fish. However, fish themselves are inefficient at producing EPA/DHA and, instead, get them through their diets. For farmed fish, the EPA/DHA supply largely comes from fish meal and fish oil. However, due to the rapid growth of the industry combined with fully exploited wild fish stocks, EPA/DHA have become short in supply. This is a well-known bottleneck for growth in the aquaculture industry, and also affects the amount of EPA/DHA available to the global population.
To address the supply challenges above, myself and Daniel Müller from the Norwegian University of Science and Technology (as of January 2020, I work for BioMar), Richard Newton from The University of Stirling and Neil Auchterlonie from IFFO undertook a study to map the global EPA and DHA cycle using a method called material flow analysis. This was to understand if there were ways to improve the efficiency for which we use these precious resources and look for ‘hotspots’ to increase supply. The results of this study were published in Nature Food.
Figure 1. Human nutritional supply of EPA and DHA measured in million tonnes, calculated by material flow analysis. Human nutritional demand based on the average daily suggested intake of 500 mg EPA+DHA/person/day, as defined by the Global Organization for EPA and DHA Omega-3 (data source: Hamilton et al., 2020)
One of the most surprising outcomes of the study was the current human nutritional supply, which was estimated to be only 30% of the demand (figure 1). This finding suggests that, today, we already face a dramatic omega-3 shortage that, without substantial measures, will drastically worsen with the expected global population boom. A multi-faceted approach, that includes a combination of reducing and recycling waste, changing diets and finding new, novel sources, is the most effective way to solve this issue.
Waste that contains large quantities of EPA and DHA occurs along the entire seafood supply chain - but is particularly a problem at the household level. We found that, at a global level, we throw away approximately one third of all the EPA/DHA we have available for eating as wild and farmed fish. While a large proportion of this is inedible, avoiding edible food waste could increase the omega-3 supply to humans by over 25%. Inedible food waste, such as organs and trimmings, also represents a substantial amount of EPA/DHA. However, this source is much harder to collect and recycle, particularly in China, where fish is often bought whole and fileted at home. Central fish processing would be required to make effective use of trimmings and by-products.
Increasing the catch of krill represents a large potential for increasing the EPA and DHA supply. Krill is the largest biomass in the world and today is only harvested at 5% of the sustainable allowed catch, as defined by Commission for the Conservation of Antarctic Marine Living Resources. However, challenges related to costs and geography limit the ability to expand in this area.
Novel sources such as microalgae and modified microbacteria and terrestrial plants are interesting options to increase the omega-3 supply. Microalgae is already in use by several fish feed companies and represents a clean source of EPA/DHA that is low in PCBs, dioxins and other environmental toxins. However, it is worth noting that the current volume of these sources is too low to fully replace fish meal and fish oil. The nutritional gap is so large that we need to both i) use the fish meal and oil we have with the highest degree of efficiency and ii) continually develop and look for new sources to add to the supply.
The nutritional gap is so large that we need to both use the fish meal and oil we have with the highest degree of efficiency and continually develop and look for new sources to add to the supply.
Full article citation: Hamilton et al., 2020. Systems approach to quantify the global omega-3 fatty acid cycle. Nature Food, 1, 59-62.