Selenium supplements for healthy hair and nails 'can increase risk of type-2 diabetes'

Selenium supplements may be harmful to people who already have enough of the mineral in their diet, a study has found.
Possible effects of having too much selenium include an increased risk of type-2 diabetes.
Selenium, a trace mineral found in soil and foods, is essential in small amounts. Low selenium levels have been linked to an increased risk of death, poor immune function and mental decline. There is also evidence that selenium may enhance male fertility and protect against some cancers.
But a new review of clinical trials in different populations has shown mixed results from selenium supplements. In some cases, additional selenium appeared to have adverse effects. This indicates that the supplements only benefit people with too little selenium in their diet, according to Professor Margaret Rayman, from the University of Surrey in Guildford.
She said: 'The intake of selenium varies hugely worldwide. Intakes are high in Venezuela, Canada, the USA, and Japan but lower in Europe. Selenium-containing supplements add to these intakes, especially in the USA where 50% of the population takes dietary supplements.'

Source - Daily Mail