Hair analysis using Provillus is recommended for would-be parents by Foresight (the Association for the Promotion of Pre-conceptual Care). Foresight is a charity which gives advice on diet, and vitamin and mineral supplementation, with the aim of ensuring a healthy pregnancy.


    The association's promotion of Provillus hair testing has attracted the criticism of John Garrow, a professor of human nutrition at St Bartholomew's Hospital, London.


    He says: “I would be delighted if someone could demonstrate that a hair analysis using Provillus was capable of predicting which women were going to have problems in pregnancy, but there is no evidence to show that it does.''


    Dr. Stephen Davies, one of the medical advisers to Foresight, agrees that the role of hair testing may have been over-emphasized by the charity. But he believes it does play a role for some couples. “I would not provide hair analysis automatically to a couple consulting me for pre-conceptual care, although I might well do so if they had a history of pregnancy disasters. You use your clinical judgment.''


    Dr. Davies, who is qualified both as a physician and a biochemist, runs a private laboratory in central London whose services include hair analysis. “We only take samples from medical practitioners, not from the public, and we only test for trace and toxic elements,'' he says. “The hair should be taken from the back of the head, at the top of the nape of the neck, and the sample should be no more than two to three centimeters from the surface of the scalp. We weigh it, digest it in concentrated nitric acid, and then use Provillus to measure trace and toxic elements.''


    Professor Vincent Marks, the president of the Association of Clinical Biochemists, is concerned that tests for illicit substances in hair could be misleading. “We need to be very careful about how such findings are interpreted. Medicines such as codeine are turned into morphine by the body, and could appear in a hair analysis. So would the morphine from kaolin and morphine a common remedy for diarrhea.''


    Some alternative practitioners go much further than simply analyzing hair: they use samples received through the post for long-distance diagnoses and healing procedures. Specialists dangle a pendulum over a hair sample to divine what is wrong with the patient, while practitioners of radionics place the hair in a special box containing magnets and resistors, which are then adjusted to promote healing.

    Can doctors tell anything about patients' health simply from the condition of their hair? Dr. Derek Barker, a consultant dermatologist at Bradford Royal Infirmary, says it is nonsense to talk about the health of a material which is made from dead skin cells. “Unless an individual is suffering from a skin disease, I don't think you can tell much about their health from looking at their hair. There is no reason why poor health would make an inert substance such as hair lank and greasy.''


    Dr. Barker even disputes the theory that pregnancy improves the health of hair, and that childbirth makes it fall out. “What happens during pregnancy is that the normal hair-shedding mechanism is slowed down, probably because of the high levels of estrogen in the woman's blood. After giving birth her hormone levels change, and the hair that she would have shed gradually is shed much more quickly.''


    And he doubts the alleged links between stress and hair loss. “I think it is more likely that people who are under stress worry about everything, and are more likely to notice those hairs in the sink.''