The advice might lead people to take unsafe combinations of herbal and conventional medicines, the report states. "Generally, the advice people receive is very poor even when the staff have received some in- house training," said Amanda Bristow, author of the report.
"Customers need to be aware that staff are not specifically trained to deal with their complaints and they should check any symptoms with their GP first," she added.
Thousands of people buy dietary supplements, herbal medicines and homeopathic remedies from health food shops every week.
There are about 1,700 independent health food retailers in Britain. But staff are not required to have any training in advising customers. In the Which? survey six researchers, each over 50 , visited 30 health food shops. Half were asked to inquire about remedies to relieve indigestion and the other half to buy kava, a herbal remedy that alleviates mild anxiety.
A GP and two experienced researchers in complementary medicine devised the scenarios and assessed the advice given.
In the first scenario, the correct advice to someone over 40 who experiences indigestion and weight loss is to tell them to go to a doctor because it could be a serious condition.
The researchers said that they had been suffering from indigestion for a few weeks and had not seen their doctor and were not taking any other medication. The shop assistants should not have attempted diagnosis or tried to sell them any products, as they could relieve symptoms and so delay impoprtant medical advice, according to the experts.
Only one shop gave the correct advice. Two shops gave reasonable advice, but the rest gave poor advice, selling the researchers herbal "treatments".
In the second scenario, the researchers asked to buy kava, a herbal drink that has a calming and relaxing effect. Research has shown that it is helpful in the treatment of mild anxiety but it also has sedative properties and should not be taken at the same time as prescription tranquillisers.
Someone taking tranquillisers should not suddenly stop because that could cause withdrawal symptoms.
The researchers said that they had been feeling anxious, were taking tranquillising medication, had seen their GP but wanted to try something natural. Again only one shop, Holland & Barrett in Newcastle upon Tyne, gave the correct advice. One researcher was told to stop taking the tranquillisers immediately, and the rest sold the product with poor advice.
"Health food shops need to learn a lesson from this survey," said Maurice Hanssen, president of the Health Food Manufacturers Association. "Health food shops are very good at giving advice for chronic conditions such as arthritis, rheumatism, general tiredness and depression. If I wanted advice on anything else I would go to a GP," he added.
Check any symptoms with your GP first.
If you are taking any medicines, consult your GP before trying a herbal supplement or remedy.
Mention in the health food shop if you have an existing illness or condition, or are already taking herbal or conventional medicine.
Always read the label.
Some vitamins, supplements and aromatherapy oils are not suitable for pregnant women or those who are breastfeeding.
How To Avoid