Health experts say there has been a proliferation of “useless” and “ineffective” iron products sold online, in supermarkets and by other retailers.

They say the tablets contain minuscule amounts – 5mg or less per serve – of elemental iron but are marketed in a way that implies they can treat iron deficiency.

Professor Geraldine Moses, a doctor of clinical pharmacy specialising in drugs information, told The Guardian that some low-dose products market themselves as “gentle on the stomach”, when the real reason they don’t cause an upset is that “there’s barely any iron” in them.

“You see powders, liquids, tablets and even expensive sachets of so-called iron-infused water that have little more iron than a bowl of cornflakes or a slice of bread,” she said.

Royal Australian College of Physicians president Professor Jennifer Martin agreed, saying the Therapeutic Goods Administration (TGA) needed to introduce stronger oversight of supplements and their marketing.

“Many iron supplements are considered ‘food-supplements’ or ‘listed medications’ by the TGA and, as such, there’s much less of a requirement to prove their efficacy compared to prescription-only or ‘registered’ medications,” she said

“There does need to be better regulatory oversight of supplements and the way they are marketed.”