The study, published in the April 2005 issue of Proceedings of the National Academy of Sciences (PNAS 102: 5074-5078), tested 30 different types of cyanobacteria tested for neurotoxin amino acid BMAA (beta-N-methylamino-L-Alanine) presence, identity and purity using liquid chromatography-MS.
Ninety-seven percent of the free-living cyanobacteria strain and 73 percent of the strains isolated from symbiosis were shown to produce BMAA.
But the researchers, led by Dr Paul Cox of California State University's Institute for Ethnomedicine and Department of Biological Science, did not test spirulina, a microalgae rich in beta carotene, iron, vitamin B12 and gamma linolenic acid that is consumed by hundreds of thousands of people around the world.
Cyanotech chairman, president and CEO Gerald Cysewski told NutraIngredients-USA.com that the omission was "unfortunate" - even though the study was carried out on live laboratory cultures of cyanobacteria, making it impossible to draw a correlation with spirulina dietary supplements.
But since the publication of the study has the potential to harm Cyanotech and Earthrise's businesses, the companies have contacted Dr Cox to request that he extend his study to include spirulina.
Cysewski said that they have also been in contact with another laboratory where tests are currently underway and results showing the absence of BMAA are expected within the next two weeks.
In the meantime, the companies issued a joint statement saying: "We have not received any complaint concerning health problems related to neurological conditions. On the contrary, the antioxidant and anti-inflammatory effects of spirulina have been demonstrated in several animal studies. These studies have shown that the antioxidants in spirulina scavenge oxygen radicals and help promote brain health."
Not only does spirulina have a long history of safe human use by the Aztecs in Mexico and the Kanembu in Chad, but it a study carried out by the United Nations Industrial Development Organization using rats and mice where spirulina made up between 10 and 35 percent of the diet found no causal link with second- or third-generation reproductive function or cancer, or presence of heavy metals, nucleic acids, pesticides or bacteria.
It has been determined GRAS by scientific procedures and FDA review.
Cyanotech and Earthrise also point out that the connection between BMAA and Alzheimer's disease is far from certain, and that some experts have expressed reservations.