The beauty supplement which helps keep skin healthy could also act as a catalyst for type 2 diabetes, a recent study has discovered.
Selenium supplements, commonly used to maintain healthy skin due to their high antioxidant levels and their ability to prevent skin cells from sun damage, could cause more harm than good in those who already have enough selenium in their diet.
Researchers from the University of Surrey in Guildford found that a possible side effect of having too much selenium in the body is an increased risk of developing type 2 diabetes, as well as poor immune function and cognitive decline.
During a series of tests, scientists discovered that high levels of selenium had positive effects on men as it increased male fertility and increased their protection against prostate, lung and bladder cancer.
However, researchers also discovered that selenium supplements only provide health benefits in those who have low levels of the mineral in their diet to begin with.
Researchers urge that selenium supplements should not be taken by those whose blood levels have 122 micrograms (mcg) per litre or higher of selenium, but gave it the go-ahead for those with low levels.
"However, there are various health benefits, and no extra risk, for people of lower selenium status (blood level less than 122 mgs per litre) who could benefit from raising their status to 130-150mg per litre, a level associated with low mortality," professor Margaret Rayman from the study, said in a statement.
"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."
This research follows a previous study by Warwick University, which discovered high levels of selenium in the blood increases cholesterol levels by 10%.
Researchers found that when the body's natural balance of selenium is altered, the body absorbs too much, which causes adverse affects to the cholesterol levels.
According to the NHS, the recommend daily allowance of selenium for women is 60mcg and 0.075mcg for men. In the UK, it's believed that the average person has a daily amount of 43mcg per day.
As well as increased diabetes risks, too much selenium can also cause a condition called selenosis, where sufferers experience the loss of hair, skin and nails.
The Department of Health recommends that selenium intake should be through eating a varied and balanced diet, including selenium-rich foods like brazil nuts, bread, fish, certain meats and eggs.