Table 3. Characteristics of the included cohort studies (n = 13).
Author, Year [Reference] | Study name | Country | Study design | No. of subjects | Male sex at enrollment (%) | Baseline age | Duration of follow-up (yrs) | Exposure | Comparisons | Exposure assessment | Outcome | Confounders | |||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Nutrients | Demographics | Anthropometrics | Medical conditions | Medications | Lifestyles | ||||||||||||
Dorant, 1994 [32] | The Netherlands Cohort Study | Netherlands | Case-cohort | 484 cases, 3,123 controls | 54.2% | Range, 55–69 | Mean, 3.3 | Garlic supplements | Use vs. no use | 150-item semiquantitative FFQ | Lung cancer | X | X | X | X | ||
Giovannucci, 1994 [25] | The Health Professional Follow-up Study Cohort | U.S. | Cohort | 205 cases, 47,949 total | 100% | Range, 40–75 | Mean, 6 | Garlic intake | ≥ 2 servings vs. 0 servings per week | Semiquantitative FFQ | Colon cancer | X | X | X | X | X | X |
Steinmetz, 1994 [26] | The Iowa Women's Health Study | U.S. | Cohort | 212 cases, 35,216 total | 0 | Mean, 61.7 | Mean, 5 | Garlic intake | 0, 0.5, ≥ 1.0 serving per week | The Willett semiquantitative FFQ | Colon cancer, proximal colon cancer, distal colon cancer | X | X | ||||
Dorant, 1995 [33] | The Netherlands Cohort Study | Netherlands | Case-cohort | 468 cases, 1,812 controls | 0 | Mean, 61.5 | 3.3 | Garlic supplements | Use vs. no use | 150-item semiquantitative FFQ | Breast cancer | X | X | X | X | X | X |
Dorant, 1996 (a) [27] | The Netherlands Cohort Study | Netherlands | Case-cohort | 478 cases, 3,346 controls | 49.58% | Range, 55–69 | Mean, 3.3 | Garlic supplements | Use vs. no use; | 150-item semiquantitative FFQ | Colon cancer; rectal cancer | X | X | X | X | ||
Use vs. other supplements | |||||||||||||||||
Dorant, 1996 (b) [34] | The Netherlands Cohort Study | Netherlands | Case-cohort | 155 cases, 3,346 controls | 36.59% | Range, 55–69 | Mean, 3.3 | Garlic supplements | Use vs. no use; | 150-item semiquantitative FFQ | Stomach cancer | X | X | X | X | ||
Use vs. other supplements | |||||||||||||||||
Sellers, 1998 [28] | The Iowa Women's Health Study | U.S. | Cohort | 241 cases, 35,216 total | 0 | Mean, 61.7 | Mean, 10 | Garlic intake | 0, ≤ 1, > 1 servings per week | 127-item FFQ | Colon cancer | X | X | ||||
Satia, 2009 [29] | The VITAL (VITamins And Lifestyle) cohort | U.S. | Cohort | 665 lung cancer cases, 428 colorectal cancer cases, 77,719 total | Lung: 48.04%; | Mean ± SD, Lung: 67.2 ± 6.6; Colon: 66.3 ± 6.7; No disease: 61.9 ± 7.4 | Mean ± SD, 5.0 ± 1.01 | Garlic supplements | Use (any use in the past 10 years) vs. no use | Questionnaire | Lung cancer, colorectal cancer | X | X | X | X | X | |
Colon: 48.01% | |||||||||||||||||
Brasky, 2011 [35] | The VITAL (VITamins And Lifestyle) cohort | U.S. | Cohort | 1,602 cases, 35,239 total | 100% | Range, 50–79 | Median, 6.1 | Garlic supplements | Use vs. no use | Questionnaire | Prostate cancer | X | X | X | X | ||
Walter, 2011 [36] | The VITAL (VITamins And Lifestyle) cohort | U.S. | Cohort | 588 cases, 66,227 total | 49.20% | Mean ± SD, 61.5 ± 7.4 | Mean ± SD, 6.5 ± 1.8 | Garlic supplement (from single supplements (and mixtures other than multivitamins) plus multivitamins) | High use vs. low use vs. no use | A 24-page self-administered, sex-specific questionnaire | Hematologic malignancy | X | X | X | X | ||
McCullough, 2012 [30] | The Cancer Prevention Study II Nutrition Cohort | U.S. | Cohort | 1,130 cases, 99,700 total | 42.95% | Mean range, 66.9–70.7 | Mean, 7 | Garlic intake; garlic supplements | < 1 clove per month, 1 clove per month, > 1 clove per month; continuous garlic intake (each clove/week); use vs. no use | 152-item modified Willett FFQ | Colorectal cancer | X | X | X | X | X | X |
Meng, 2013 [31] | The Nurses' Health Study and the Health Professionals Follow-Up Study | U.S. | Cohort | 1,339 colorectal cancer cases, 1,054 colon cancer cases, 634 proximal colon cancer cases, 397 distal colon cancer cases, 285 rectal cancer cases, 121,700 total in NHS; 1,029 colorectal cancer cases, 811 colon cancer cases, 345 proximal colon cancer cases, 314 distal colon cancer cases, 218 rectal cancer cases, 51,529 total in HPFS | 0 in NHS, 100% in HPFS | 30–55 in NHS; 40–75 in HPFS | 24 in NHS, 22 in HPFS | Garlic intake; garlic supplements | < 1 clove per month, 1–3 cloves per month, 1 clove per week, 2–4 cloves per week, 5–6 cloves per week, ≥ 1 clove per day; use vs. no use | Semiquantitative FFQ with up to 130 foods | Colorectal cancer, colon cancer, proximal colon cancer, distal colon cancer, rectal cancer | X | X | X | X | X | X |
Kim, 2018 [37] | The Nurses' Health Study and the Health Professionals Follow-Up Study | U.S. | Cohort | 292 cases in NHS and HPFS, 121,700 total in NHS; 51,529 total in HPFS | 0 in NHS, 100% in HPFS | 30–55 in NHS; 40–75 in HPFS | 30 in both NHS and HPFS | Garlic intake | 0–1 clove per week, 1–4 cloves per week, ≥ 5 cloves per week | Semiquantitative FFQ | Gastric cancer | X | X | X | X | X | X |
FFQ, food frequency questionnaire; NHS, Nurses' Health Study; HPFS, Health Professionals Follow-up Study.