Much smaller amounts are found in meat and milk, and these fatty acids are absent from plants. However, they are important components of human cell membranes, such as the retina and the cerebral cortex in DHA, and are required for normal development and cell function.
Although EPA and DHA can be made in the body from the omega-3 essential fatty acid alpha-linolenic acid, which is found in a number of seeds, seed oils, and nuts (e.g., canola oil and walnuts), it is our ability to do so , very limited and seems to decrease with age so largely relying on getting EPA and DHA preformed from the diet.
The UK recommends a daily intake of 450 mg EPA and DHA, which can be achieved with a weekly serving of 140 g of oily fish. However, only about a quarter of adults in the UK consume oily fish regularly, the average intake is low and intake in children is even lower. Low intake may be linked to the perceived discomfort of oily fish, lack of relevant cooking skills, or associated cooking odors.
Alternative sources for EPA and DHA.
A Review in Nutrition BulletinResearchers from Southampton University and Rothamsted Research are exploring options for an alternative source of EPA and DHA that can be upscaled and is sustainable. It discusses how the challenges associated with ensuring adequate supplies can be met with seed oils from transgenic plants, which have been developed for the production of EPA and DHA.
It has been estimated that marine springs can currently only provide 16% of the EPA and DHA needed to ensure everyone on the planet achieves the recommended daily intake. The catch of wild fish has remained unchanged since the 1990s, but the consumption of farmed fish has increased significantly. However, fish is also dependent on a food supply with omega-3 fatty acids, which is why the rearing of farmed fish represents a great demand for the global fish oil supply.
Krill oil has been suggested as an alternative source of EPA plus DHA, but concerns exist about its effects on marine food webs in the South Atlantic.
Algae oils currently make up 2% of human EPA / DHA consumption, but fermentation and processing costs are currently much higher than for fish oil production.
Vegetable oils from genetically modified plants.
Vegetable oils made from genetically modified plants are another alternative source of EPA and DHA and can overcome concerns about the palatability, sustainability, and contamination of fish oil, as well as the problems associated with algae oils and krill oil. The genetic insertion of desaturase and elongase enzymes from yeast and algae into plants that naturally produce alpha-linoleic acid has enabled the development of canola (canola) and Camelina sativa (C. sativa) strains that can synthesize EPA and DHA.
Studies in healthy men and women have now shown that the incorporation and accumulation of EPA and DHA in plasma lipids after dietary supplementation with oil from transgenic C. sativa is just as good as that achieved with fish oil and the C. sativa oil was good tolerated.
Field trials have already shown the stability and robustness of the transgenic trait of C. sativa, but current legislation in Europe remains an obstacle to the commercial cultivation of transgenic plants for human consumption. The authors speculate that new opportunities might arise once Britain leaves the EU.
Judy Buttriss is Director General of the British Nutrition Foundation.