Blue-green algae toxic to liver?

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from: Health Canada

http://www.hc-sc.gc.ca/english/protection/warnings/1999/9969ebk.htm

Blue-green algae
What are blue-green algae and why do they contain “naturally-occurring toxins”?
Blue-green algae, scientifically known as cyanobacteria, are organisms that form in shallow, warm, slow moving or still water. Historically, large scale harvesting of blue-green algae masses was done for research purposes, to study their properties, and their possible use as therapeutic and antibiotic agents, as well as their potential as agricultural commodities. They can also be harvested from outdoor ponds or natural lakes. At present, blue-green algae are manufactured and sold in some pharmacies and health food stores as food supplements, often in tablet or caplet form. While in the water, some species of cyanobacteria naturally produce toxins, as a by-product of their metabolism. The toxins are then stored in the algal cell-like structure. Toxin concentration levels are affected by environmental factors such as exposure to sun, depth of the water and the type of minerals in the water. Levels of the toxins will fluctuate with environmental changes, and are not predictable. Without scientific testing, there is no way to detect the presence or level of toxins in the algae.

Why is Health Canada concerned about blue-green algae tablets and capsules?
The algae that are harvested to manufacture blue-green algae tablets and capsules may be contaminated with toxins. Although Health Canada has asked manufacturers to conduct screening for the toxins, the screening may not be done consistently. Recently, a researcher at the University of Alberta conducted an independent sampling, to test the level of one of the toxins, Microcystin-LR of natural health products containing blue-green algae. Of the nine randomly selected samples that were tested, all showed levels of Microcystin-LR which exceeded the levels considered safe for daily consumption by both Health Canada and the World Health Organization. The findings have been validated by Health Canada, where an additional six products were also tested and found to contain varying levels of microcystin, including one significantly high level. A more common variety of blue-green algae, Spirulina, has not been found to contain toxins at harmful levels. However, more thorough analysis is required, since growing conditions are generally unknown.

How harmful are the toxins?
As mentioned, the levels of toxins produced and stored by the algae are unpredictable. The degree of contamination, and by extension the degree of risk, depends on when the algae were harvested, what types of algae were present, and how strong the presence of the toxins were at the time of harvest. Each batch will have a different level of contamination. It is therefore difficult to measure the degree of risk in each product, or even in each batch of the same product. Each batch would need to be screened. The degree of risk is also dependent on how much and how long a person is exposed to the toxin. Microcystins are toxins which accumulate in the liver, and can cause damage over the long term. Because of their comparatively lower body weight, children are particularly at risk of liver damage, as well as gastro-intestinal effects, if they are exposed to the toxin in large amounts over an extended period of time. At low to moderate levels of exposure, the effects may be reversible. High levels of exposure to the toxins can have irreversible effects.

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How are these products regulated?
The majority of products containing blue-green algae are sold as nutritional supplements, which would be classified as a food. As a food, they are subject to supervision by Health Canada and the Canadian Food Inspection Agency, without any specific regulation, so long as there are no medical claims made, and the products themselves are safe. If medical claims are made, the products are then considered to be drugs, subject to the requirements and regulations on safety, quality and effectiveness that all drugs undergo in order to be approved for sale in Canada.

What is Health Canada doing about the situation?
As a precautionary measure, consumers have been advised by Health Canada to discontinue the use of use of blue-green algal products in children and apply caution in their own use of the products, until evidence of their safety can be firmly established. At present, Health Canada is investigating the situation and conducting a market survey of the Canadian market to determine the exact nature of the blue-green algal products, as well as how the products are being used, in order to establish the potential for exposure to the toxins. Further testing would then be conducted to analyse the levels present in the products. Depending on the outcome, follow-up steps will be taken, including possible compliance action. Because of the fluctuation of toxin levels in the algae, it would be important to determine how manufacturers address the potential hazard by quality control mechanisms or manufacturing processes and whether these are done consistently.

What about the use of blue green algae as a treatment for Attention Deficit Disorder in children?
Health Canada has not received any evidence which supports use of blue-green algae as an effective treatment for Attention Deficit Disorder in children. Meanwhile, there is a potential risk of children being exposed to harmful levels of toxins, if they ingest blue-green algae products, particularly if they ingest the products for an extended period of time. As a precaution, until such time as they can be proven safe for use in children, the use of blue-green algae products should be discontinued in children.

What involvement does the new Office of Natural Health Products have in this situation?
The Office of Natural Health Products was created specifically to deal with issues like this one, where questions of safety and quality are raised over products of natural origin. Once functional, the new Office will be distinctly capable of navigating the complicated territory of natural health products, ensuring that the products are consistently safe, of high quality, and properly labelled. Although the Office is in the midst of formation, it will be monitoring the situation closely.