The web search was conducted in April 2012, to identify websites selling NSs for the treatment and prevention of diabetes mellitus. The research was performed using 3 of the main search engines commonly used to seek information, Google, Yahoo and Bing!. The key term used was "diabetes nutritional supplements". As shown in Figure 1, the first 30 occurrences on the 3 search engines were analysed to identify websites selling NSs. Sites were included if (a) they sold supplements directly to the consumer, (b) they did not require a password to obtain the ingredients, (c) they showed the complete list of ingredients and (d) they were in English. Sites were excluded if they (a) were broken links and (b) were not organised by disease category. Twenty-eight websites were identified as sales websites; 12 of these were mentioned in more than one search engine and were only considered once. All the websites identified in Yahoo were the same identified in Bing!. Six ones didn't fit the inclusion criteria. Only 10 sites suited our study purpose.
Under the "Diabetes" category we analysed the first nutritional supplement suggested by the website (the supplements were not shown in alphabetical order).
The content of each website was evaluated according to the main indications provided by the National Institute of Health Office of Dietary Supplements (NIH-ODS) on how to evaluate health information on the internet. In particular, we evaluated how easy it was to find the person responsible for the website, the indication of the health information source and a possible reviewer of it, the presence of bibliographical references supporting the NS, and the presence of the FDA disclaimer statement. Testimonials, medical indications, safety claims and side effects provided by the site were also recorded.
In order to analyse scientific evidence of the efficacy of these supplements, a PubMed search was carried out on ingredients shared by at least 3 NSs. The bibliographical search for the specific ingredient was carried out, in addition to the following key words defined using the MeSH Database on PubMed: "Diabetes Mellitus" [Mesh]. The search was limited to randomized controlled trials (RCTs), systematic reviews (SRs) and meta-analyses (MAs) studies conducted on humans in the last 10 years.
The authoritative fact sheets on NSs provided by the NIH-ODS and the references reported by the sales websites in relation to the ingredients selected in this study were also considered. The FDA website was also used as a resource.
The literature analysis focused on the findings regarding the efficacy of these ingredients in treating diabetes mellitus, the method of administration, the indications for specific diabetes-related diseases and the possible side effects.
BMC Public Health. 2013;13(777) © 2013 BioMed Central, Ltd.
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