EFSA affirms safety of selenium-enriched yeast
The European Food Safety Authority's Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food (AFC) found that the majority of products identified by the petitioners would provide an average daily selenium dose of 100 micrograms or less.
“Average dietary intake of selenium by the European population has been estimated to lie in the range of 27-70 micrograms per day,” stated the panel.
“Assuming a mean dietary selenium intake in the range of 30-70 micrograms per day, consumption of an additional food supplement containing 100 micrograms of selenium would result in a total daily selenium intake of 130-170 micrograms per day in an adult at an average level of dietary exposure.”
Selenium levels have been falling in Europe since the EU imposed levies on wheat imports from the US, where soil selenium levels are high.
As a result, average intake of selenium in the UK has fallen from 60 to 34 micrograms per day, leading to calls from some to enrich soil and fertilizers with selenium to boost public consumption. Selenium-enriched fertilizers are used in Finland.
The European recommended daily intake (RDI) is 65 micrograms. The recommended EC Tolerable Upper Intake Level for selenium is 300 micrograms per day.
The petitioners included Wassen (UK), Lallemand (France), Lesaffre (France), Pharma Nord Vojens (Denmark), Higher Nature (UK), Béres Pharmaceuticals Company, Vireco Ltd., and Procon.
Preparation methods
The panel stated that sufficient data were presented by five of the petitioners concerning the identity and form of the organo-selenium compounds contained in the yeast.
The safety conclusions related only to selenium-enriched yeasts produced by culture in the presence of sodium selenite. The final, marketed dried form should contain no more than 2.5 mg selenium per gram.
According to this preparation method, the selenomethionine is the predominant organic selenium form, making up between 60 and 85 per cent of the total selenium. Other organic selenium compounds such as selenocysteine should not exceed 10 per cent, said the panel.
Safety
If the selenium-enriched yeast complies with the general product characteristics outlined above, the panel concluded that product would not present any safety concern.
However, excessive intakes are associated with toxicity. According to scientific studies, no toxicity is observed in the range of 240-1510 micrograms per day.
“Investigations into the health effects of high dietary intakes of selenium in populations living in the seleniferous areas of South Dakota, Venezuela and China have indicated that the highest long-term daily intake that can be ingested without the development of toxicity in most individuals is approximately 800 micrograms while prolonged intakes of daily selenium doses of 1000 micrograms or greater may cause adverse reactions,” stated the panel.
Despite these figure, the Tolerable Upper Intake Level for selenium is set at 300 micrograms per day, and a food supplement containing 200 micrograms taken in addition to dietary intakes would mean individuals risk exceeding this level.
Bioavailability
“Despite the higher bioavailability of selenium from organic sources such as selenium-enriched yeast, the toxicity of these organic forms has been shown in a number of studies in experimental animals to be lower than that of inorganic selenite or selenate,” stated the panel.
“This suggests that the increased bioavailability may be counterbalanced by lower toxicity.”
Insufficient data
The panel’s safety conclusions apply only to selenium-enriched yeast produced using selenium selenite. The panel ruled that yeast produced using selenium dioxide or selenium-aminoate have insufficient information on the selenium species present in the products.
“The Panel considered therefore that it was not possible to conclude that the profile of the selenium species in these two selenium-enriched yeast products is likely to be similar to those reported for the other five products, with selenomethionine accounting for approximately 60 to 85 per cent of the total selenium.
“Due to deficiencies in the bioavailability and safety data provided on the selenium species likely to be present in these products, the Panel was unable to evaluate their safety.”
