128 June 2012, Vol. 24, No. 6 Lipid Technology Feature Microalgae as an alternative source of omega-3 long chain polyunsaturated fatty acids Eline Ryckebosch, Charlotte Bruneel, Koenraad Muylaert, Imogen Foubert E.R. is PhD student, C.B. is postdoctoral researcher and I.F. is professor at KU Leuven Kulak, Research Unit Food and Lipids, Department of Molecular and Microbial Systems, Leuven Food Science and Nutrition Research Centre (LFoRCe), Etienne Sabbelaan 53, 8500 Kortrijk, Belgium. E-mail: Eline.Ryckebosch@kuleuven-kulak.be K.M. is at KU Leuven Kulak, Aquatic Biology, Department of Biology, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium. Summary The health benefits of omega-3 long chain polyunsaturated fatty acids (omega-3 LC-PUFA) are recognized worldwide. The traditional source ofomega-3 LC-PUFA is fish. However, global consumer needs cannot be supplied by the current global fish harvest. Therefore, new sources of omega-3 LC-PUFA have to be found. Microalgae are producers of omega-3 LC-PUFA and a potential alternative for seafood. Other sources ofomega-3 LC-PUFA include krill oil, calamari oil and genetically engineered land plant crops. Introduction Omega-3 polyunsaturated fatty acids (omega-3 PUFA) are a speci- fic group of polyunsaturated fatty acids in which the first double bond is located between the third and fourth carbon atom counting from the methyl end of the fatty acid. There are short chain (SC, f C 18 ) and long chain (LC, F C 20 ) omega-3 PUFA. Refer- ences to SC omega-3 PUFAs generally relate to a-linolenic acid (ALA, 18:3 n-3) or, less frequently, stearidonic acid (SDA, 18:4 n- 3). ALA is found in vegetable oils such as flaxseed oil (l55% of total FA), rapeseed oil (l10% of total FA) and soybean oil (l8% of total FA). Stearidonic acid is available in a genetically modified soybean oil. The important health benefits are however asso- ciated with longer chain omega-3 LC-PUFA and particularly eico- sapentaenoic acid (EPA, 20:5 n-3), docosapentaenoic acid (DPA, 22:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3). Omega-3 LC- PUFA reduce the risk of heart disease, have a positive impact on incidence of stroke, rheumatoid arthritis, kidney function, growth and development in infants/children, and are able to lower high contents of blood fats. In addition to these physical health benefits, omega-3 LC-PUFA may have benefits for neurop- sychiatric disorders including depression and dementia [1]. Photosynthetic organisms, including microalgae, are the pri- mary natural producers of omega-3 LC-PUFA, the biosynthesis of which starts from ALA (Figure 1). In humans, the conversion of the omega-3 SC-PUFA to the omega-3 LC-PUFA is however limited and varies within individuals. In men, the conversion of ALA to EPA can be up to 8%, whereas the conversion of ALA to DHA is very low (0 to 4%). The conversion of ALA to omega-3 LC-PUFA is more efficient in women (conversion of ALA to EPA can be up to 21%, conversion of ALA to DHA can be up to 9%). This difference is probably linked to the needs of the developing foetus and the breast-fed infant. However, there is competition between omega- 6 and omega-3 fatty acids for the desaturation enzymes neces- sary for the conversion. Omega-6 fatty acids, such as linolenic acid (LA, 18:3 n-6), are consumed much more than omega-3 fatty acids in our western diet. Therefore dietary intake of omega-3 LC-PUFA is essential. To that end, there is an increased interest from the industry to enrich food with omega-3 LC-PUFA and to use omega-3 LC-PUFA in food/nutritional supplements. The recommended minimal daily intake is set at 250 mg. i 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.lipid-technology.com DOI 10.1002/lite.201200197 Figure 1. Pathway for the biosynthesis of omega-3 LC-PUFA in microalgae