Turmeric (Curcuma longa, Zingiberaceae) rhizome has been used as a medicine for thousands of years. It has been used as a tonic, for blood cleansing, and for treatment of skin diseases, stomach disorders, anorexia, rhinitis, sinusitis, cough, complications of diabetes, liver and bile disorders, and rheumatism. Curcumin and other curcuminoids are major active components of turmeric. Curcumin has antioxidant and anti-inflammatory activities, and it is being studied for potential benefits in cancer, Alzheimer’s disease, arthritis, and dyslipidemia. The purpose of this study was to provide a comprehensive bibliometric analysis of the literature on curcumin. The aim was to analyze curcumin publications to identify major research themes, research locations, author affiliations, and journal citation data.
The Web of Science Core Collection database was searched in November 2018 using the search string “curcumin.” The search string identified publications with the word “curcumin” or its derivatives in the title, abstract, or keywords. There were no restrictions on the publication type or language. An additional search was conducted to identify publications that mentioned “Curcuma longa” or “turmeric” but not “curcumin.” VOSviewer software was used to extract and analyze data from the publications and to generate bubble maps to visualize the results.
The primary “curcumin” search identified a total of 18,036 publications, including 14,315 original articles and 1378 review articles. More than half of the articles were published since 2014, and 99.1% were published in English. The authors were affiliated with 7729 organizations located in 125 countries. Countries with the highest publication counts were the United States (22.3% of publications), China (19.7%), India (17.3%), Japan (5.5%), and South Korea (4.9%). China was the country with the highest publication count since 2014, followed by India, the United States, Iran, and Italy. Organizations that published greater numbers of publications had on average higher counts of citations per publication, but the same pattern was not seen either for countries or for journals.
The top five Web of Science categories for these publications were pharmacology and pharmacy, biochemistry and molecular biology, oncology, multidisciplinary chemistry, and medicinal chemistry. Common themes of the publications were related to the effects of curcumin and its derivatives on cancer (n = 2583 publications), inflammation (n = 1210), oxidative stress (n = 1266), and Alzheimer’s disease (n = 746). The former three were also notable for high citations-per-paper values. Keywords related to potential mechanisms of curcumin included nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), nitric oxide synthase, and tumor necrosis factor-α (TNF-α). Keyword frequency was analyzed by a decade of publication, and “drug delivery,” “bioavailability,” and “nanoparticles” emerged as top keywords since 2010.
A small number of original articles (n = 691) had the term “clinical trial” in the title or abstract. “C3 complex” was a common term among the clinical trial publications. C3 Complex (Sabinsa Corporation; East Windsor, New Jersey) is a turmeric rhizome extract that contains three curcuminoids and is standardized to 95% curcuminoids. Clinical trials evaluated C3 Complex in the context of Alzheimer’s disease, skin conditions, osteoarthritis, inflammation associated with metabolic syndrome and obesity, effects on the gut microbiome, and cancer (most frequently breast, colon, colorectal, pancreatic, and prostate cancers).
The secondary search for “Curcuma longa” and “turmeric” identified a total of 3920 publications. India was the country with the highest publication count, followed by China, the United States, Thailand, and Japan. Compared to the “curcumin” search, this search yielded keywords that were more related to plant science, constituents and extracts, and antimicrobial and antioxidant activity. The top five Web of Science subject categories for these publications were pharmacology and pharmacy, food science technology, plant sciences, medicinal chemistry, and integrative and complementary medicine.
The authors state that most of the curcumin publications focused on biochemistry, chemistry, oncology, and pharmacology. After 2014, major research foci have been cancer, inflammation, and oxidative stress. One limitation of this bibliometric analysis is the use of a single database to identify and analyze publications. Another limitation is that very recent trends were not likely to be identified because they have not yet yielded significant numbers of publications. However, the analysis did identify drug delivery and bioavailability of curcumin as an emerging research theme since 2010.
The authors declare no conflicts of interest in the research.
Yeung AWK, Horbańczuk M, Tzvetkov NT, et al. Curcumin: Total-scale analysis of the scientific literature. Molecules. April 9, 2019;24(7):1393. doi: 10.3390/molecules24071393.