Vegetarians and people who avoid animal products for cultural reasons may be consuming gelatin in medicines without realising it, a study has suggested.
Experts surveyed 500 people and found many on a restricted diet would prefer not to take a medicine containing animal products even if no alternative was available.
The survey was carried out among a mixed-ethnic population from Manchester who had consulted their doctor with urological symptoms. Of the sample, 283 people were taking medicines and 200 said they were not supposed to eat animal products.
Most (88%) of the 200 patients following a restricted diet said they would prefer to take medicines containing only vegetable products, with only 11% saying it did not matter to them. Among the 176 who would prefer vegetarian-only medicines, more than half (100) said they would take a drug containing an animal product if no other alternative was available.
But the remainder (76 patients) said they would not knowingly do so. Only around one in five of the 176 patients in this group said they would check with their doctor or pharmacist to see if the drug's content was against their dietary requirements or beliefs.
Gelatin is a commonly used coating agent in medicines, but can also be used as a thickener.
Writing in the Postgraduate Medical Journal, the experts, from Manchester Royal Infirmary and South West Yorkshire Partnership NHS Foundation Trust, said doctors "are fairly ignorant" about some of the substances used in medicines.
They said their study had found that "patients practising dietetic restriction do not ask what the formulation contains before commencing drug treatment, which puts them at risk of transgressing their belief.
"This may simply be due to ignorance about what an oral medication contains, not reading, or being able to read, the patient information leaflet which contains a list of excipients (carrier substances), or belief that the doctor or pharmacist involved in the prescription would tell them if the medication contained ingredients that might contravene their beliefs."
The authors concluded: "Substitution of gelatin with vegetable-based alternatives and clearer labelling on drug packaging are alternative strategies to help minimise the risks of inadvertently contravening a patient's dietetic beliefs when prescribing oral medication."