Faecal bacteria found in algae-based supplements 'a significant health worry'
Popular algae-based health supplements like spirulina and super greens may be hiding a grim secret - as a team of Irish researchers found faecal bacteria in a range of products.
A study of eight samples of algae-based 'superfoods' also found that some of the faecal organisms were resistant to certain types of antibiotics.
It was described as a "significant public health concern" to find the bacteria in each sample tested.
The research was carried out by seven experts from the departments of medicine and microbiology at NUI Galway, and the findings were published in this month's issue of the 'Irish Medical Journal'.
Spirulina, chlorella and super greens are three types of algae-based health supplements, which have become increasingly popular in recent years. They contain protein, vitamins and minerals and are marketed as having a broad range of health benefits.
The research team at NUI Galway was prompted to study the products after a batch of one such supplement, chlorella, was found to be contaminated with salmonella in Ireland in 2015.
This resulted in affected batches being recalled from consumers.
The team bought five samples of chlorella, two samples of spirulina, and one sample of super greens from an Irish retail outlet; and tested them for the presence of faecal bacteria and antibiotic resistance in the bacteria found.
All eight samples were found to contain faecal organisms, including enterococci, enterobacteriaceae, and clostridium species.
Evidence of resistance to antibiotics was also detected, leading the researchers to recommend that clinicians caring for vulnerable patients should be aware of the potential risk of exposure to antimicrobial-resistant bacteria associated with the products.
"The algae that form the basis of these products can be cultivated by a number of methods, including open systems in direct contact with the general environment," the researchers reported.
"Antimicrobial resistance... found in other foods, especially meat products, is a well-reported phenomenon and consumption of contaminated foods is considered to be one mechanism by which humans acquire or become colonised with multidrug-resistant organisms.
"This project indicates that these algae-based products ... are frequently contaminated with faecal-type bacteria, which in some instances carry antimicrobial resistance determinants of significant public health concern," they added.
The researchers noted that the study had been confined to a small number of products, but claimed that there was "sufficient basis" for clinicians with vulnerable patients to be aware of the associated risks.
They also stated that more extensive surveys were required to establish the extent to which antimicrobial-resistant bacteria are present in such products, so as to inform decision regarding the need for improved practices or regulation.