Table 1. Study characteristics.
| First Author | Publication year | Country | Study design | Total participants | Total mean (SD) age | Zinc measurement method | Source of sampling |
|---|---|---|---|---|---|---|---|
| Yiwen Zhang [26] | 2022 | United States | Cohort | 47240 | 66.14 (0.27) | NA | FFQ |
| Mehmet Kaba [70] | 2014 | Turkey | Case-control | 62 | 64.06 (1.31) | AAS | Serum |
| KS Adedapo [88] | 2012 | Nigeria | Case-control | 120 | 66.85 (1.66) | AAS using a direct method | Serum |
| Collins Amadi [57] | 2020 | Nigeria | Case-control | 440 | 69.35 (0.35) | AAS using a direct method | Serum |
| Katarzyna Białkowska [60] | 2018 | Poland | Case-control | 394 | 77 | ICP-MS technique | Serum |
| Ayşe Eken [89] | 2016 | Turkey | Case-control | 131 | 61.27 (7.14) | AAS with a Zeaman Background Correction, flame atomic absorption spectrometer | Serum |
| Yenny Gómez [90] | 2007 | Venezuela | Case-control | 40 | 54.29 (NA) | ETA-AAS | Prostatic fluid |
| Jingkang Guo [91] | 2007 | NA | Case-control | 115 | NA | ICP-MS | Scalp hair |
| Enrique Gutiérrez-González [67] | 2018 | Spain | Case-control | 1961 | 65.95 (0.25) | Dietary zinc intake estimated | FFQ |
| Martin Igbokwe [68] | 2021 | Nigeria | Cross-sectional | 82 | 71.78 (1.05) | PIXE | Toe-nail |
| Lina Mustafa khedir Abdelmajid [99] | 2022 | Sudan | Case-control | 60 | NA | AAS | Serum |
| Alan R. Kristal [20] | 2010 | United States | Cohort | 9559 | 62.77(0.38) | FFQ and a structured supplement-use questionnaire | FFQ |
| Marion M. Lee [92] | 1998 | China | Case-control | 398 | NA | FFQ and face-to-face interviews | FFQ |
| Xiao-Meng Li [93] | 2005 | China | Cross-sectional | 3940 | 68.47 (1.05) | Deproteinization method using a Perkin-Elmer 503 AAS | Serum |
| Jue Tao Lim [102] | 2019 | Singapore | Case-control | 255 | NA | ICP-MS | Serum |
| Abeer M. Mahmoud [24] | 2016 | United States | Case-control | 208 | 66.30 (0.24) | Block FFQ | FFQ |
| Rana Kareem Mohammed [100] | 2015 | Iraq | Case-control | 50 | NA | AAS | Serum |
| Augusta Chinyere Nsonwu-Anyanwu [76] | 2022 | Nigeria | Case-control | 90 | 36.76 (2.04) | Wet acid digestion method | Serum |
| Wasiu Eniola Olooto [78] | 2021 | Nigeria | Case-control | 75 | NA | AAS | Serum |
| Bridget Obiageli Onyema-iloh [94] | 2014 | Nigeria | Case-control | 100 | NA | AAS | Serum |
| Saleh A. K. Saleh [95] | 2017 | Saudi Arabia | Case-control | 174 | 69.10 (1.70) | ICP-MS | Scalp hair |
| Chao Tan [96] | 2011 | China | Cross-sectional | 113 | NA | ICP-MS | Scalp hair |
| H.D. Vlajinac [97] | 1997 | Serbia | Case-control | 303 | 71.16 (NA) | Measurements of consumption using standard cups, spoons, and slices | Zinc intake |
| Victor C. Wakwe [83] | 2019 | Nigeria | Cross-sectional | 440 | 69.35 (0.38) | AAS | Serum |
| Elizabeth G. Willden [98] | 1975 | United Kingdom | Case-control | 92 | NA | AAS | Serum |
| Hasan Yari [101] | 2015 | Iran | Case-control | 72 | 65.30 (1.20) | Polarography | Serum |
| Vladimir Zaichick [86] | 2019 | Russia | Case-control | 146 | 61.32 (2.94) | EDXRF | Prostatic fluid |
| Michael F. Leitzmann [74] | 2003 | United States | Cohort | 46974 | 54.34 (0.64) | Zinc intake | FFQ |
| J.O.Ogunlewe [77] | 1989 | Nigeria | Case-control | 127 | 63.81 (2.34) | AAS | Serum and prostatic tissue |
| T.Goel [65] | 2006 | India | Case-control | 80 | NA | AAS | Serum |
| Ahmet Aydin [58] | 2006 | Turkey | Case-control | 85 | 65.44 (1.37) | Flame AAS | Serum |
| V.YE.Zaichick [87] | 1996 | Russia | Case-control | 91 | 56.18 (7.90) | XRF | Prostatic fluid |
| D.W.West [84] | 1991 | United States | Case-control | 1037 | NA | FFQ | FFQ |
| Song-Yi Park [21] | 2013 | United States | Case-control | 1175 | 68.97 (0.09) | ICP-MS | Serum |
| Alejandro Gonzalez [66] | 2009 | United States | Cohort | 35242 | NA | Zinc intake | FFQ |
| Laurence N. Kolonel [72] | 1988 | United States | Case-control | 1351 | NA | FFQ | FFQ |
| A. Feustel [62] | 1986 | Germany | Case-control | 147 | 53.70 (NA) | Flame AAS | Serum and erythrocytes |
| Golgis Karimi [71] | 2012 | Malaysia | Case-control | 100 | 72.05 (0.35) | ICP-MS | Hair and nail |
| Silvano Gallus[64] | 2007 | Italy | Case-control | 2745 | 62.20 (NA) | Zinc intake | FFQ |
| Elizabeth A. Platz [80] | 2002 | United States | Case-control | 342 | 66.03 (0.05) | Furnace AAS and flame AAS | Nail |
| M. Jain [69] | 1994 | India | Case-control | 50 | NA | AAS | Serum and prostatic tissues |
| Alan R. Kristal [73] | 1999 | United States | Case-control | 1363 | NA | Zinc intake | FFQ |
| M. I. Yilmaz [85] | 2004 | Turkey | Case-control | 121 | 65.01 | Flame AAS | Serum |
| Habibe Ozmen [79] | 2006 | Turkey | Case-control | 41 | 69.32 (3.10) | AAS | Serum |
| Swen-Olof Andersson [22] | 1996 | Sweden | Case-control | 1056 | 70.65 (0.05) | Zinc intake | FFQ |
| Muhammad Abdul Qayyum [81] | 2014 | Pakistan | Case-control | 394 | 51.70 (NA) | AAS | Serum, scalp hair, and nail |
| Pamela Christudoss [61] | 2011 | India | Case-control | 83 | NA | AAS | Serum and tissue |
| Saleh A.K. Saleh [82] | 2020 | Saudi Arabia | Case-control | 92 | 67.17 (1.04) | ICP-MS | Serum |
| Onyinyechi Bede-Ojimadu [59] | 2023 | Nigeria | Case-control | 273 | NA | ICP-MS | Urine and serum |
| Lois D. Mcbean [75] | 1974 | United States | Case-control | 95 | 49.00 (NA) | AAS | Serum |
| A.Feustel [63] | 1989 | Germany | Case-control | 75 | 68.75 (NA) | Flame AAS | Serum |
| Yuqing Zhang [19] | 2009 | United States | Case-control | 4110 | 60.15 (1.48) | Supplementation use using a structured questionnaire | FFQ |
Abbreviations: NA: not available; AAS: atomic absorption spectrometry; FFQ: food frequency questionnaire; ICP-MS: inductively coupled plasma mass spectroscopy; PIXE: Particle induced X-ray emission; EDXRF: energy dispersive X-ray fluorescent; XRF: X-ray fluorescence.