The process of study selection is outlined in Fig. 1. The literature search identified 7111 potentially relevant records. After removal of duplicates, 5206 records were excluded by screening on the basis of title and/or abstract. Thereafter, 107 records were excluded after assessing the full text. A total of 33 SRs were finally included in the present umbrella review [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50]. These SRs were published between 07/2009 and 03/2022. A list of excluded records after full-text assessment including justifications for exclusion is provided in Supplementary Material 4.

Among these 33 SRs, 29 included solely RCTs [18,19,20,21,22,23,24,25,26,27,28,29, 31, 32, 35,36,37,38,39,40,41,42, 44,45,46,47,48,49,50]. One SR considered solely cohort studies [30] and three SRs additionally addressed RCTs [33, 34, 43]. In total, 26 SRs conducted an MA [20,21,22,23,24,25,26,27,28,29, 32, 35,36,37,38,39,40,41,42, 44,45,46,47,48,49,50] and seven SRs were without MA [18, 19, 30, 31, 33, 34, 43]. One SR with MA analysed dose–response relationships [35]. Some of the primary studies were incorporated more than once into different SRs, but overall there was only a “slight” overlap of primary studies of 2.2%, determined as corrected covered area according to Pieper et al. [15], see Supplementary Material 5. BW was addressed in 29 SRs [18,19,20, 22, 23, 26,27,28,29,30,31,32,33,34,35, 37,38,39,