Analysis, occurrence, and toxicity of ß-methylaminoalanine (BMAA)

A risk for the consumer?

image of Analysis, occurrence, and toxicity of ß-methylaminoalanine (BMAA)

In 2005 an international research team reported that cyanobacteria living in symbiosis with plants or living free in lakes and oceans are able to produce the non-protein amino acid -methylaminoalanine, also known as BMAA. Some years earlier the American scientists in this team had reported that BMAA could be found not only in the brain from diseased patients of the Chamorro people on Guam having the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and Parkinsons dementia (PD), but also in two patients with Alzheimers disease in Canada. A very high incidence of ALS and PD among the Chamorro people had been known since after the Second World War and had been linked to the use of flour prepared from the seeds of the local cycad tree, which had been shown to contain BMAA. As surface water is frequently purified and used as drinking water, it was hypothesised that low level of contamination of drinking water with BMAA from the cyanobacteria might reach the human brain and over time result in neurodegenerative disease. This reports aimed at scrutinizing this hypothesis, and concludes that BMAA is unlikely to occur in drinking water and be responsible for these neurological diseases in the Western World.



Summary in English

Since the 1940’s the cause of the highly raised incidence of amyotrophic lateral sclerosis (ALS) and Parkinsons dementia complex (PDC) within the local Chamorro population of Guam and neighboring islands of the south-west Pacific Ocean has been searched for. Even though the incidence now has decreased from its peak in the 1950’s (179/100 000 for men and 61/100 000 for women) to numbers that compared to incidence in the Western world in the 1990s (1.9/100 000) are only a few times greater, the search for the main causative factor is still ongoing. Factors hypothesised and discarded after analysis with scientific scrutiny include hereditary causes, environmental causes, infectious agents, prions, and micronutrient deficiency. None of these have been thought to give the whole answer. The traditional diet was the only factor identified in epidemiological studies to be linked to the disease complex. In particular, the use of flour prepared form cycad seeds as a staple food by the Chamorro population became a topic of discussion in the 1960’s. Since then it has been clearly demonstrated that there is a connection between dietary exposure to cycad and high incidence of ALS-PDC on Guam.


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