Out of 13 drugs recommended by health shops to overcome depression only one actually has any sound scientific backing, according to experts.
The experts have said that St John's Wort is the only alternative medicine proven to have an effect.
They added that many others including gingko biloba, ginseng, cat's claw, royal jelly and liquid tonic have no firm evidence base and "have potentially serious drug interactions".
The experts, Joyce Reed, a senior house officer at St James's University Hospital in Leeds, and Peter Trigwell, a consultant in liaison psychiatry at Leeds General Infirmary, published their findings in Psychiatric Bulletin, from the Royal College of Psychiatrists.
They obtained these results following survey of staff at 10 health food shops within three miles of Leeds city centre for their recommendations on treating mild to moderate depression.
The symptoms reported by the customers included lethargy, disturbed sleep, lack of concentration, poor appetite, and not feeling oneself.
Five health stores were visited and five were telephoned, with most of the staff asking extra questions before putting forward recommendations. Only two workers asked if a GP had been consulted, and three specifically asked if the customer felt depressed in their mood.
One staff explained that she was not medically trained, and advised a consultation with a GP first.
It was also noted that staff did not make any comments on the oral contraceptive pill that the researcher explained that she was currently prescribed in spite of evidence that St John's Wort can reduce effectiveness of the pill.
Overall 13 treatments were suggested, with multivitamins being the most popular. Staff also made a number of suggestions for changing diet and lifestyle.
The authors said patients are becoming increasingly well informed about depression and its treatment, and often seek alternatives to traditional approaches.
However researchers warned, "Only one of the 13 preparations suggested, St John's Wort, is supported by an evidence base.
"There is evidence for a putative role in the treatment of depression for a further two: ginseng and B-complex vitamins. Furthermore, staff are unlikely to warn customers about potential interactions and adverse side-effects. "This study raises concerns about the virtually complete separation and independence of complementary and alternative medicine services from the National Health Service and pharmaceutical agencies."
According to the authors many herbal remedies may have beneficial properties "which could be used to great advantage if an adequate evidence base was developed.
"However, owing to the lack of overlap between the two sectors little is understood about each in either area. A more integrated approach would allow patients to benefit from herbal preparations, such as St John's Wort, with optimum safety."
In addition the authors said that the "public nature" of shops may lead employees to avoid asking personal questions "resulting in the suggestion of less-appropriate remedies for the treatment of depression.
"Many of the remedies were offered for a general 'boost' or 'pick-me-up' (eg. multivitamins), but with little evidence base. It is also worth noting that a large proportion of people may purchase the medicine without consulting shop staff."