Millions of people swear by vitamin supplements. But many are wasting their time and some could even be harming themselves, argues Dr Chris van Tulleken.
In November 1912 a party of three men and 16 dogs set out from a remote base in eastern Antarctica to explore a series of crevasses many hundreds of miles away. Three months later just one of the men returned. His name was Douglas Mawson. His skin was peeling off and his hair was falling out. He had lost almost half his body weight. He recounted what Sir Edmund Hillary described as "the greatest story of lone survival in the history of polar exploration".
A month into their journey, one of the team, along with the tent, most of the provisions and six dogs plunged into a crevasse, never to be seen again. Mawson and the other surviving member, Xavier Mertz, started to return to base, surviving in part by eating the remaining dogs. After a few weeks Mertz developed stomach pains and diarrhoea. Then his skin started to peel off and his hair fell out. He died incontinent and delirious a few days later.
Mawson suffered similar symptoms. With the kind of understatement typical of his generation of polar explorers he described the skin of the soles of his feet peeling off: "The sight of my feet gave me quite a shock, for the thickened skin of the soles had separated in each case as a complete layer... The new skin underneath was very much abraded and raw."