Is spirulina safe? Can it contain harmful toxins? An article that deals with and explains which algae are harmful and which are not, avoiding unjustified alarmism.
Recently, Anses, the French Health Security Agency, has issued a food alert, claiming to have received many reports of even serious side reactions following the intake of Spirulina supplements, possibly contaminated with heavy metals and / or toxins.
Tests conducted in 2000 by Gilroy (the researcher most cited by the alarmists), have found the presence of toxins, albeit low, in some supplements based on Spirulina.
ConsumerLab, an independent non-profit American body that regularly tests vitamins and supplements, advises all Spirulina consumers, stating that supplements containing this algae may also be a vehicle of very harmful toxins. If we then add that, among the most dangerous algal toxins, there are the microcystins, a family of hepatotoxins capable of causing very serious damage to the liver, we are faced with a strange paradox:
How is it that a seaweed, which according to some researches has a detoxifying and repairing effect on the liver, can at the same time be potentially deleterious and harmful to that same organ, or to others?
What’s the truth?
We will try to give an accurate answer supported by clear evidence. First of all it is important to make some clarifications:
a) when we talk about spirulina we refer to one of the about 2000 families of cyanobacteria present in nature, which are not only very different from each other, morphologically, biochemically and physiologically, but live, feed, replicate in different places and in different chemical and physical conditions. In short, we can’t generalize.
b) The European Food Safety Authority (EFSA), a body responsible for certifying the suitability and safety of food at European level, recognizes spirulina as a food (such as salad to understand) and therefore not associated with any risk for health.
c) the FDA, the US government agency that deals with the regulation of food and pharmaceutical products and which directly depends on the Department of Health and Human Services of the United States, after careful checks, granted the spirulina the status of “Generally Recognized As Safe” (GRAS) “, and its beneplacet to commercialization in the United States.
d) there is a regular and proven tradition of spirulina consumption over the centuries (at least since the fourteenth century AD), without any registered side effects.
e) There is no study to date that has in subject the Arthrospira Platensis (Spirulina), which has detected any potential harm connected its use.
So how can we explain the contrary reports that we find online from time to time?
Of all the kinds of cyanobacteria that exist in nature, some are actually able to produce toxins that are potentially harmful to the liver, the brain or the dermis. Although today the physiological mechanism underlying the production of these cyanotoxins is not known, some evidences show that some of them, for example, microcystins can be transported outside the cell in the surrounding aquatic environment through active transport processes that entail a non-negligible energy expenditure. This would suggest that cyanobacteria can use the release of toxins to defend themselves, and / or attack competing organisms. 
The Higher Institute of Public Health in its report, lists some of these toxic algae that can be commonly found in our country:
Spirulina, or rather the Arthrospira type (species: Platensis) is not part of these toxic cyanobacteria.
How come some toxins were detected in Spirulina supplements?
Although it is not able to produce toxins that are harmful to human health, spirulina could come into contact with it if it were naturally grownin open puddles, lakes or with non-pure or controlled waters, in case also other cyanobacteria with toxic capacity were present.
If we go to read the details of Gilroy’s multifaceted study, this is exactly what happened: the 87 samples of Spirulina algae examined came from the crops of the Upper Klamath Lake, a natural basin located in Oregon, in which there were in those years several blooms of M aeruginosa, an alga able to produce very dangerous hepatotoxins. The risk is even higher for the consumers of A-flos Aquae, another edible algae such as Spirulina, which often coexists in nature with M.Aeruginosa, thus exposing itself to contamination. In any case, it should be remembered that of all the Gilroy contaminated specimens of Spirulina, only one presented some doses of microcistine higher than the recommended value.
On 5 May 1999, the Canadian Health Protection Branch, after having warned consumers that algae-based products could contain harmful toxins to the liver, decided to examine the extent of the problem by conducting strict analysis, through the Office of Natural Health Products, the Therapeutic Products Program and the Food Directorate of the Health Protection Branch on many samples of supplements on the market. On September 27, the results were made public: in all samples containing exclusively Spirulina, no toxin was detected. On the basis of the results obtained, the products obtained exclusively from Spirulina blue-green algae are no longer considered to be a health risk related to microcystin in Canada.
The same article by Anses, the French Health Agency, with which we started, refers to an internal report which is reiterated in a sufficiently clear way that although many cyanobacteria in nature produce toxins, there are no such records in the scientific literature about Arthrospira Platensis, except for 2 specific cases ; also in this circumstance, the samples came from two lakes in Kenya, where there are often blooms of Anabaena and Microcystis, two very toxic algae.
The report therefore invites consumers to carefully trace the origin of their Spirulina supplements, paying particular attention to those arriving from India or China. In an analysis conducted by Jang in 2008 on 36 samples containing spirulina, 94% were positive for the microcystin.
So…cultivating spirulina at home and in an artificial environment erases all risk?
Yes, as long as you take the necessary precautions: filtered or networked water and quality inoculum, purchased from an accredited and accurate supplier who can certify the purity of the original sample by analysis. Our inoculum is certified and safe, we buy it from laboratories of proven trust and in compliance with the highest quality standards.
 Rapala J, Sivonen K, Lyra C, Niemela SI. Variation of microcystins, cyanobacterial hepatotoxin in Anabaena spp. as a function of growth stimuli. Appl Environ Microbiol 1997;64:2206-12.
 Ballot, A., L. Krienitz, K. Kotut, C. Wiegand, et S. Pflugmacher. 2005. “Cyanobacteria and
cyanobacterial toxins in the alkaline crater lakes Sonachi and Simbi, Kenya.” Harmful
Algae 4 (1):139-150. doi: 10.1016/j.hal.2004.01.001.