[Dietary supplements--evaluation of patient inquiries at a drug information service]

Dietary supplements are a product group of foods, which are meant to supplement the general nutrition with micronutrients and other substances. They are widely used in Germany. We evaluated the frequency of their use and of information requirements concerning dietary supplements in patients who contacted the independent drug information service at TU Dresden.

All inquiries from 2008 to 2010 were evaluated regarding information requirement about dietary supplements, the kind of products used and characteristics of patients using supplements. Sociodemographic characteristics, kind and number of drugs and dietary supplements as well as underlying diseases were recorded from the inquiring patients.

23.3 % of persons looking for advice used dietary supplements. The most frequently used product groups included vitamins and minerals (52.5 %) as well as plant extracts (14.0 %). Information requirements were especially high for plant extracts and for products containing glucosamine/chondroitin and lutein/zeaxanthin. Users of dietary supplements were exposed to a higher number of different products than non-users.

Information requirements were primarily detected for products without clearly proven benefits or for supplements which are advertised to relieve certain diseases or symptoms although the product characteristics do not support such utilization. The frequency of use of dietary supplements among patients which already receive multiple medications substantiates the necessity to include dietary supplements in assessments of drug interactions and to scrutinize indications for supplement use.