Algal supplementation of vegetarian eating patterns improves plasma and serum docosahexaenoic acid concentrations and omega-3 indices: a systematic literature review

J Hum Nutr Diet. 2017 Dec;30(6):693-699. doi: 10.1111/jhn.12474. Epub 2017 Apr 17.


Background: Vegetarians are likely to have lower intakes of preformed docosahexaenoic acid (DHA) than omnivorous populations who consume fish and animal products. As such, vegetarian populations have omega-3 indices up to 60% lower than those who consume marine products. Algae, the primary producer of DHA in the marine food chain, offer an alternative source of DHA for those who do not consume marine or animal products. This systematic review aims to examine the evidence for the relationship between supplementation with algal forms of DHA and increased DHA concentrations in vegetarian populations.

Methods: The SCOPUS, Science Direct and Web of Science scientific databases were searched to identify relevant studies assessing the effect of algal DHA consumption by vegetarian (including vegan) populations.

Results: Four randomised controlled trials and two prospective cohort studies met the inclusion criteria. All included studies reported algal sources of DHA significantly improve DHA concentrations (including plasma, serum, platelet and red blood cell fractions), as well as omega-3 indices, in vegetarian populations. An evident time or dose response was not apparent given the small number of studies to date.

Conclusions: Future studies should address long chain n-3 polyunsaturated fatty acid deficiencies in vegetarian populations using algal DHA and explore the potential physiological and health improvements in these individuals.

Keywords: algal; docosahexaenoic acid; omega-3; supplementation; vegetarian.

Publication types

  • Review

MeSH terms

  • Cyanobacteria*
  • Diet, Vegetarian*
  • Docosahexaenoic Acids / administration & dosage
  • Docosahexaenoic Acids / blood*
  • Docosahexaenoic Acids / deficiency
  • Dose-Response Relationship, Drug
  • Eicosapentaenoic Acid / administration & dosage
  • Eicosapentaenoic Acid / blood
  • Fatty Acids, Omega-3 / administration & dosage
  • Fatty Acids, Omega-3 / blood*
  • Fatty Acids, Omega-3 / deficiency
  • Humans
  • Randomized Controlled Trials as Topic


  • Fatty Acids, Omega-3
  • Docosahexaenoic Acids
  • Eicosapentaenoic Acid