Algae Supplements


The health effects of algae supplements have not been as widely researched as those of fish oils.

Algae are highly concentrated sources of vitamins and minerals and therefore have considerable potential as nutritional supplements. Their PUFA content varies greatly according to species, of which there are many thousands.

Only a small number of algae species are used to make supplements that contain EPA and DHA, which are usually present in smaller quantities than in fish oils. Some seaweeds, such as wakame, contain EPA but not DHA.

Some algae, including popular blue-green algae (more strictly cyanobacteria), contain a good balance of ALA and LA but negligible amounts of EPA and DHA. They are not therefore comparable to fish oils.

An Omega 3 Source for Fish: Fish cannot make the omega 3 fatty acids that are found in abundance in their oils. They obtain them from the microalgae they consume, either directly or via krill and copepods. Microalgae, along with other types of algae, are now being directly exploited for their n-3 PUFAs and other nutrients.


Compared with fish oil supplements, there are fewer scientific studies for algae supplements. This may be partly because algae contain lower levels of long chain n-3 PUFA than fish oils.

There is, however, a sizeable body of research material relating to the fatty acids composition of algae. One interesting aspect of algae research is the potential for influencing the fatty acid composition of alga using various culture regimes. This subject is outside the scope of the current project but will be considered for future treatment.

Some algae, such as the seaweed Wakame, contain worthwhile amounts of EPA while a few, including Thraustochitrids such as Schizochytrium, contain significant levels of DHA but only low levels of EPA.

The study of fatty acids in algae is still in its infancy, however there are a number of algae-derived supplements on the market, including a Schizochytrium product developed by Udo Erasmus and marketed by Flora.

We set out to answer the following questions during this project:

Are blue-green algae really algae?
Which types of algae are used in supplements?
Is there a contamination issue?
Is there a sustainability issue?
How do algae supplements compare with fish oil supplements?
What side effects are there?

Some other questions have already been answered for fish oils (see part 2 of this project), as they relate specifically to EPA and DHA:

What specific benefits do they provide? What factors reduce their effectiveness? How long is it before they have an impact?

Visit the Fish Oil Supplements page of this project for answers to these questions

Are blue-green algae really algae?

Supplements marketed as blue-green algae are slightly misleadingly labeled. Blue-green algae are now officially classified as cyanobacteria, a subset of the bacteria domain. They are classified in this way because their cells are prokaryotic, meaning that the nuclear material in their cells is not enclosed by a membrane.

True algae are eukaryotic as their cells contain membrane-bound structures, including chloroplasts in some cases (used for photosynthesis). Instead of chloroplasts, cyanobacteria perform photosynthesis via thylakoid membranes.

Cyanobacteria are commonly treated as a form of algae as they have much in common with microalgae. We shall therefore include blue-green algae within the scope of this project.

Which types of algae are used in supplements?

Algae form an extremely diverse group of organisms. The following types of algae are used to make supplements:

Cyanobacteria (blue-green algae)

These are usually classified as microalgae, although they belong to the bacteria kingdom. They include Spirulina and Chlorella, which are both widely available in supplement form.

Blue-green algae contain ALA and LA, together with many other nutrients, but they do not contain significant quantities of EPA and DHA, the n-3 highly unsaturated fatty acids (HUFA) that are abundant in fish oils.

Microalgae (other than cyanobacteria)

Microalgae are ultimately a source of n-3 fatty acids for fish, occupying the lowest level of the marine food chain. Many of them contain significant levels of EPA and DHA. Some examples are included in the FAO Fisheries Technical Paper (see research sources at the end of this page).


Seaweed, which in its different forms belongs to various multicellular groups of algae, is widely used as food, especially in coastal communities. Some types of seaweed, such as Kelp, are also used in nutritional supplements. One type of Kelp, Wakame, contains fairly high levels of the n-3 PUFA EPA, as well as other important nutrients. Compared with fatty fish, however, the EPA content of Wakame is lower and Wakame contains no DHA. Wakame is used extensively in Japanese cooking and is now available as supplements, as well as in its more traditional dried form.

Other algae

As mentioned in the introduction, algae of the genus Schizochytrium, contain significant levels of DHA and have therefore been selected for supplement manufacture.

Is there a contamination issue?

Algae supplements are marketed using the assertion that they do not suffer from the contamination issues associated with fish oil. However the weight of evidence for fish oil suggests that contamination is not a significant health issue (see Part 2 of this project).

The issue of contaminants in algae was not addressed in the scientific research literature used during this project. Further research is required in order to form a view.

Is there a sustainability issue?

As with the contamination question, the research material did not deal with sustainability. Further research is required and ee shall remain open-minded, even though algae supplement marketers advance the idea of sustainability as a distinct advantage over fish oil supplements.

How do algae supplements compare with fish oil supplements?

We have already seen that fish oils are generally higher in EPA and DHA, the important highly unsaturated fatty acids (HUFAs), than algae supplements (although algae supplements contain high levels of other nutrients).

Spirulina is not an alternative to Fish Oils: Spirulina is heavily marketed as a vegetarian or vegan alternative to fish oils. This is misleading because Spirulina is not a significant source of EPA or DHA, the two fish oil PUFAs. It does contain ALA, GLA and a range of other beneficial nutrients, including high quality protein.

Algae supplements have a clear appeal to vegans and vegetarians, who are unlikely to be able to get DHA and EPA from any source other than algae, whether in the form of supplements or unprocessed seaweeds such as Wakame.

Algae supplementation has been used in place of fish oils for infant formulas. The supplement DHASCO, developed and marketed by Martek Biosciences Corporation, has been approved for use in infant formula in several countries, including the United Kingdom, the United States, Canada, Australia, New Zealand and the Netherlands.

DHASCO is a blend of oil from the alga Crypthecodinium cohnii and high oleic sunflower oil, which gives a product that contains 40-45% DHA by weight. Although several clinical trials have been conducted in order to determine the efficacy, safety and side effects of DHASCO and its sister product ARASCO, analysis of these studies is outside the scope of this project.

What side effects are there?

None of the research studies used during this project addressed the issue of adverse effects. We shall therefore keep an open mind until we are able to find more relevant material.