LAUSR

The number of systematic reviews and meta analysis (SR/MA) is increasing, also in the field of nutrition. The aim of this work was to analyse the frequency of exploring the effects of specific nutritional interventions in studies published as SR/MA focused on cancer prevention. The main study was a systematic survey of SR/MA on nutrition in cancer prevention published between 2010 and 2018 identified through search in 3 databases. The protocol of the study was registered (CRD42019121116 in PROSPERO). All steps of the survey were done by two reviewers independently with any conflicts resolved by discussion or by the third reviewer. The quality and risk of bias were assessed using AMSTAR 2 and ROBIS tools amid subsample of 101 SR/MA. We grouped all dietetic interventions by year and analysed frequency. Among 737 SR/MA meeting the inclusion criteria, an average number of publications was 83/year ranging from 38 (in 2010) to 118 (in 2015). The most commonly studied food categories were: non-alcoholic beverages (127 publications in total; on average 14/year) and vitamins and/or minerals (157 publications in total; on average 17/ year) with coffee as one of the most popular (on average 7 SR/MA per year). The most commonly analysed vitamins were vitamin D, C, and E, while amid minerals calcium and selenium. Red meat and processed meat were comparably popular with about 4 dedicated publications every year. SR/MA about fruits and vegetables and alcohol appeared on average about 8 times every year. The overall quality of SR/MA assessed in a subsample of randomly selected 101 of included articles was poor (97% were classified as having a low quality). In SR/MA published between 2010 and 2018, each food category appears many times, while for example coffee - many times every year. Detailed analysis per food item may help identify potential research waste in the field of nutrition in cancer prevention. Currently, coffee is the ‘hottest’ nutritional topic in cancer prevention. The general quality of SR/MA published in the field of cancer prevention is low.