You may know that I am always cautious about selenium. I fully recognise that adequate selenium is essential. But I always suggest that a low dose is likely able to take most people from inadequate to adequate status. By that I mean 100 or, possibly, 200 micrograms a day - or even lower.
There have been too many papers which identified negative effects from higher dose selenium over long periods.
Low population selenium status is associated with increased prevalence of thyroid disease
Low selenium status is associated with increased risk of thyroid disease. Increased selenium intake may reduce the risk in areas of low selenium intake which exist not only in China but in many other parts of the world.
Full paper available here: