Acute selenium toxicity associated with a dietary supplement

Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Archives of internal medicine (Impact Factor: 17.33). 02/2010; 170(3):256-61. DOI: 10.1001/archinternmed.2009.495
Source: PubMed


Selenium is an element necessary for normal cellular function, but it can have toxic effects at high doses. We investigated an outbreak of acute selenium poisoning.
A case was defined as the onset of symptoms of selenium toxicity in a person within 2 weeks after ingesting a dietary supplement manufactured by "Company A," purchased after January 1, 2008. We conducted case finding, administered initial and 90-day follow-up questionnaires to affected persons, and obtained laboratory data where available.
The source of the outbreak was identified as a liquid dietary supplement that contained 200 times the labeled concentration of selenium. Of 201 cases identified in 10 states, 1 person was hospitalized. The median estimated dose of selenium consumed was 41 749 microg/d (recommended dietary allowance is 55 microg/d). Frequently reported symptoms included diarrhea (78%), fatigue (75%), hair loss (72%), joint pain (70%), nail discoloration or brittleness (61%), and nausea (58%). Symptoms persisting 90 days or longer included fingernail discoloration and loss (52%), fatigue (35%), and hair loss (29%). The mean initial serum selenium concentration of 8 patients was 751 microg/L (reference range, < or =125 microg/L). The mean initial urine selenium concentration of 7 patients was 166 microg/24 h (reference range, < or =55 microg/24 h).
Toxic concentrations of selenium in a liquid dietary supplement resulted in a widespread outbreak. Had the manufacturers been held to standards used in the pharmaceutical industry, it may have been prevented.

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    • "Selenium has been claimed to reduce the occurrence of a large number of cancers. Favorable effects of selenium intake on AIDS signs, fertility, skin disorders and asthma have also been reported [1] [2] [3]. In humans, selenium deficiency can cause endemic cardiomyopathy known as Keshan disease, which affects children and women of child-bearing age, in particular. "
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    ABSTRACT: The aims of this study were the screening of main effects and optimization of selenium determination in plasma samples with experimental design methodology.
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    • "Another high-dose selenium case consisting of the use of a liquid dietary supplement containing 200 times the labeled concentration of selenium was reported in the United States [44]. Of the 201 cases identified in 10 states, 1 person was hospitalized. "
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    • "Tremors also occurred but in a lower number of subjects ( 20% approximately ) . The occurrence of ataxia was not investigated in this study , but this sign had been observed in 13% of 201 patients exposed to such Se - containing misformulated supplement in a pre - vious report ( MacFarquhar et al . , 2010 ) . The natural history of this acute Se toxicity is peculiar : in most cases ( 57 . 1% ) , an improvement of symptoms was reported after 2 . 5 years , whereas 33 . 3% of the study group reported no improvement and 9 . 5% reported worsen - ing , thus contradicting previous reports on shorter recovery periods ( Morris and Crane , 2013 ) "
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    ABSTRACT: Selenium is a metalloid of considerable interest in the human from both a toxicological and a nutritional perspective, with a very narrow safe range of intake. Acute selenium intoxication is followed by adverse effects on the nervous system with special clinical relevance, while the neurotoxicity of long-term overexposure is less characterized and recognized. We aimed to address this issue from a public health perspective, focusing on both laboratory studies and the few epidemiologic human studies available, with emphasis on their methodological strengths and limitations. The frequently overlooked differences in toxicity and biological activity of selenium compounds are also outlined. In addition to lethargy, dizziness, motor weakness and paresthesias, an excess risk of amyotrophic lateral sclerosis is the effect on the nervous system which has been more consistently associated with chronic low-level selenium overexposure, particularly to its inorganic compounds. Additional research efforts are needed to better elucidate the neurotoxic effects exerted by selenium overexposure.
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