Nutrition & Metabolism Classics: a disconnect between highly cited and highly accessed articles

To find out which of the published articles had a significant impact on the scientific community, we first looked at the articles that were highly cited. We used two sources to obtain citation numbers, Thomson Reuters Web of Knowledge and Google Scholar. Thomson Reuters indexes only selected journals in Web of Knowledge and provides Impact Factors via its annual Journal Citation Report, which has included Nutrition & Metabolism since 2006. In contrast, Google Scholar has no editorial restrictions on indexing and includes all articles published since the journal launched in 2004, therefore giving a more comprehensive and non-selective overview of citations. We selected the top 10 highly cited articles in each indexing service (Tables 1 &2). It is interesting to note that the top 10 highly cited articles, with two exceptions, were different in these two databases. A reason is that nine of the eleven highly cited articles in Google Scholar are from 2004–2005. Therefore, for an appropriate comparison, we identified highly cited articles in Google Scholar published since 2006 (Table 3). By comparing the number of citations for the same article across both indexing services we have been able to identify several articles that appear to have been cited almost exclusively by articles in journals that are themselves indexed in the Web of Knowledge. Given the stringent criteria required to be indexed by Thomson Reuters, this may well be a sign of quality. Unsurprisingly, most articles receive a greater number of citations in Google Scholar. An interesting feature of this analysis was that 60% of the highly cited papers in Thomas Reuters were research articles. In contrast, 50% of the highly cited papers according to Google Scholar were review articles. In general, review articles are the most highly cited articles in a journal, so we were pleased to note that a significant number of our research articles topped the rankings in both these indexing services. Overall, the variability in the list of high-impact articles identified by these two services highlights the inconsistency of different indexing services, and provides further evidence that the citation indexing is an imprecise measure of article quality and its impact on research.

Further surprises came when we analyzed highly accessed articles. They were all review articles except for one commentary (Table 4), and only 50% of the highly accessed reviews were also highly cited according to Google Scholar (Table 1), supporting the conclusion that our articles are also being accessed regularly by individuals who are not actively involved in writing scientific articles: the general public. The three most highly accessed reviews cover the topics of low-carbohydrate diets, fructose and the impact of high protein on kidney function, respectively, and these subject areas were replicated throughout the top 10. They are clearly of interest to the general public; searching the article titles using the search engine Google revealed that all continue to be discussed and cited in online conversations, maintaining a steady stream of accesses and ensuring the articles continue to be referenced and explored long after they were published. We think this in part due to their open-access status. The benefits of open access are two-fold: encouraging public interest in the biology behind nutrition, and giving interested parties, including clinicians, access to peer-reviewed information on nutrition and diet.

Nutrition & Metabolism strives to serve the academic and clinical communities and the public by publishing the highest quality research across all areas of nutrition in an accessible, open-access format. Ten years after we published our first article, the journal continues to expand and improve. In spite of the weaknesses highlighted above, we remain particularly proud that the journal Impact Factor has increased consistently since 2009. Beyond the simple matter of citations, Nutrition & Metabolism has always been a forum for controversial and groundbreaking studies, and we aim to encourage debate amongst our readership. We believe that publication is just the start of an article’s life, and greatly appreciate the numerous letters, commentaries and reviews we receive each year.

This evaluation indicates that Nutrition & Metabolism has published research and review articles across a broad range of subjects that are appreciated and cited by authors. Further, many of its articles are also of interest to the general public. We are gratified that Nutrition & Metabolism is responding to the interests of both the academic community and the public at large. With your support we will continue to provide this service to the best of our abilities.