Spirulina - not so super?

Spirulina, the green/blue bug that grows in water has some wonderful health benefits. This is hardly surprising as it is a plant, and most plants have wonderful health benefits if you eat them in large amounts, and minimal processing.
Technically Spirulina is two different types of cyanobacteria: Arthrospira platensis, and Arthrospira maxima. Cyanobacteria are group of pond scum bacteria. They are colored green to blue and get their energy from photosynthesis like green plants.

There is another cyanbacteria called Anabena flos-aquae which is not healthy for you at all. It produces Anatoxin-a neurotoxin with some very nasty effects. This neurotoxin can kill within minutes and sometimes wipes out groups of animals who drink from the same contaminated pond. In saying all this I have never heard of animals dieing in NZ from this toxin.

A study looked at Anatoxin-a in spirulina drinks and supplements (in the US market). They found 3 of the 39 Spirulina products (7.7%) where contaminated with Anatoxin-a. This may hit the headlines around the world as the papers like to report anything negative about supplements.

Reading the study more closely the anatoxin-a levels were between 2.50 to 33 μg / g. Mice die when 385 μg of anatoxin-a per kg of body weight is injected into their bodies. Therefore assuming same toxity level in humans and the average human being 75kg, you would need to injest 28.9 mg of anatoxin-a to die. With the highest food/supplement levels of 33 μg / g you would need to eat 875 kg of contaminated spirulina! (This assumes that all toxin eaten makes it into your blood stream.)

Have you ever eaten 875 kg in a meal? Thus rest assured that your spirulina is not going to poison you!

Reference: Rellán et al First detection of anatoxin-a in human and animal dietary supplements containing cyanobacteria Food and Chemical Toxicology
Volume 47, Issue 9, September 2009, Pages 2189-2195