magic. The Chief Medical Officer for England, Dame Sally Davies, has stated that homeopathic preparations are "rubbish" and do not serve as anything more than placebos. Jack Killen, acting deputy director of the National Center for Complementary and Alternative Medicine, says homeopathy "goes beyond current understanding of chemistry and physics". He adds: "There is, to my knowledge, no condition for which homeopathy has been proven to be an effective treatment." Ben Goldacre says that homeopaths who misrepresent scientific evidence to a scientifically illiterate public, have "... walled themselves off from academic medicine, and critique has been all too often met with avoidance rather than argument". Homeopaths often prefer to ignore meta-analyses in favour of cherry picked positive results, such as by promoting a particular observational study (one which Goldacre describes as "little more than a customer-satisfaction survey") as if it were more informative than a series of randomized controlled trials. Referring specifically to homeopathy, the British House of Commons Science and Technology Committee has stated: The National Center for Complementary and Alternative Medicine of the United States' National Institutes of Health states: Ben Goldacre noted that in the early days of homeopathy, when medicine was dogmatic and frequently worse than doing nothing, homeopathy at least failed to make matters worse: In lieu of standard medical treatment On clinical grounds, patients who choose to use homeopathy in preference to normal medicine risk missing timely diagnosis and effective treatment, thereby worsening the outcomes of serious conditions. Critics of homeopathy have cited individual cases of patients of homeopathy failing to receive proper treatment for diseases that could have been easily diagnosed and managed with conventional medicine and who have died as a result, and the "marketing practice" of criticizing and downplaying the effectiveness of mainstream medicine. Homeopaths claim that use of conventional medicines will "push the disease deeper" and cause more serious conditions, a process referred to as "suppression". Some homeopaths (particularly those who are non-physicians) advise their patients against immunization. Some homeopaths suggest that vaccines be replaced with homeopathic "nosodes", created from biological materials such as pus, diseased tissue, bacilli from sputum or (in the case of "bowel nosodes") faeces. While Hahnemann was opposed to such preparations, modern homeopaths often use them although there is no evidence to indicate they have any beneficial effects. Cases of homeopaths advising against the use of anti-malarial drugs have been identified. This puts visitors to the