This very question has long being occupying the minds of both the advocates and critics of bath salts. For many years there was debate about whether the minerals from bath salts could be absorbed into the human skin through soaking. Many claimed it did happen, some disagreed altogether, while others said that it is the combination of the salts and the ultra-violet radiation from the sun that is the reason why the Israeli beach vacation cure works.
Luckily, in 2006 Rosemary Waring (a British biochemist at the University of Birmingham) put an end to the debate. She undertook scientific work which proved that magnesium is well absorbed by the skin through bathing. Waring measured this through measuring magnesium and sulphate in the blood and urine before and after people had bathed in Epsom salts. She found them to be higher after the baths – with 16 out of 19 people having more magnesium and sulphate in their blood after the baths than before. This has proven that the minerals from bath salts can be absorbed in to the human skin, which explains how they might work.