Table 1.
Study design and demographic description of the included studies with a “high quality of evidence” (quality assessment score is of at least 10).
| Author (Year) | Cohort Allocation | Study Design | Type of Disease/Symptom | Intervention | Comparator | Duration | Blind | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Number | M/F | Dosage | Number | M/F | Dosage | ||||||
| Marx et al. (2017) [17] |
Australia | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 24 | 8/16 | 300 mg of ginger extract (5% gingerol)/cap, 4 capsules/day | 27 | 11/16 | 300 mg of placebo/cap, 4 capsules/day | 5 days | Double-blind |
| Sanaati et al. (2016) [18] |
Iran | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 15 | 0/15 | 500 mg of powdered ginger/cap, 2 capsules/day and DMA regimen * | 15 | 0/15 | DMA regimen * | 5 days before and 5 days after chemotherapy | Double-blind |
| Iran | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 15 | 0/15 | 500 mg of powdered ginger/cap, 2 capsules/day and DMA regimen * | 15 | 0/15 | 500 mg of powdered chamomile/cap, 2 capsules/day and DMA regimen * | 5 days before and 5 days after chemotherapy | Double-blind | |
| Thamlikitkul et al. (2016) [19] |
Thailand | Crossover randomized controlled trial | Chemotherapy-induced nausea and vomiting | Second cycle: 19; Third cycle: 15 |
Second cycle: 0/19 Third cycle: 0/15 |
500 mg of powdered ginger/cap, 2 capsules/day | Second cycle: 15; Third cycle: 19 |
Second cycle: 0/15; Third cycle: 0/19 |
500 mg of placebo/cap, 2 capsules/day | 5 days at each second and third cycle of chemotherapy | Double-blind |
| Li et al. (2017) [20] |
China | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 71 | 53/18 | 250 mg of powdered ginger (5% gingerols)/cap, 2 capsules/day, bid | 69 | 47/22 | 250 mg of corn starch/cap, 2 capsules/day, bid | 5 days | Double-blind |
| Ansari et al. (2016) [21] |
Iran | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 57 | 0/57 | 250 mg of powdered ginger/cap, 4 capsules/day, bid | 62 | 0/62 | 250 mg of starch/cap, 4 capsules/day, bid | 3 days for each 3 cycles | Single-blind |
| Sharifzadeh et al. (2018) [4] |
Iran | Randomized controlled trial | Nausea and vomiting because of pregnancy | 28 | 0/28 | 500 mg of ginger/cap, 2 capsules/day | 26 | 0/26 | 40 mg of vitamin B6/cap, 2 capsules/day | 4 days | Triple- blind |
| Iran | Randomized controlled trial | Nausea and vomiting because of pregnancy | 28 | 0/28 | 500 mg of ginger/cap, 2 capsules/day | 23 | 0/23 | 2 placebo capsules/day | 4 days | Triple-blind | |
| Matsumura et al. (2015) [22] |
United States | Randomized controlled trial | Muscle damage and delayed onset muscle soreness | 10 | 5/5 | 4 g of powdered ginger in capsule(s)/day | 10 | 5/5 | 4 g of dextrose in capsule(s)/day | 5 days | Double-blind |
| Martins et al. (2018) [23] |
Brazil | Randomized controlled trial | Migraine | 30 | 4/26 | 200 mg of ginger extract/cap, 2 capsules/dose + 100 mg of ketoprofen (i.v.) | 30 | 4/26 | 200 mg of cellulose/cap, 2 capsules/dose + 100 mg of ketoprofen (i.v.) | Single dose | Double-blind |
| Arzati et al. (2017) [24] |
Iran | Randomized controlled trial | Type 2 diabetes mellitus | 25 | 9/16 | 500 mg of ginger/cap, 4 capsules/day | 25 | 7/18 | 500 mg of wheat flour/cap, 4 capsules/day | 10 weeks | Double-blind |
| Attari et al. (2016) [25] |
Iran | Randomized controlled trial | Obesity | 39 | 0/39 | 1 g of powdered ginger/tab, 2 tablets/day | 31 | 0/31 | 1 g of corn starch and other excipients/tab, 2tablets/day | 12 weeks | Double-blind |
| Attari et al. (2015) [26] |
Iran | Randomized controlled trial | Obesity management | 39 | 0/39 | 1 g of powdered ginger/tab, 2 tablets/day | 31 | 0/31 | 1 g of corn starch/tab, 2 tablets/day | 12 weeks | Double-blind |
| Mozaffari-Khosravi et al. (2016) [13] |
Iran | Randomized controlled trial | Knee osteoarthritis | 50 | 3/47 | 500 mg of powdered ginger/cap, 2 capsules/day | 50 | 7/43 | 500 mg of starch/cap, 2 capsules/day | 3 months | Double-blind |
| Aryaeian et al. (2019) [27] |
Iran | Randomized controlled trial | Active rheumatoid arthritis | 33 | 4/29 | 750 mg of powdered ginger/cap, 2 capsules/day | 30 | 3/27 | 750 mg of wheat flour/cap, 2 capsules/day | 12 weeks | Double-blind |
| Kashefi et al. (2015) [28] |
Iran | Randomized controlled trial | Heavy menstrual bleeding | 43 (1st month); 41 (2nd month); 38 (3rd month) | 0/43 (1st month) 0/41 (2nd month) 0/38 (3rd month) | 250 mg of powdered ginger/cap, 3 capsules/day | 43 (1st month); 38 (2nd month); 33 (3rd month) | 0/43 (1st month) 0/38 (2nd month) 0/33 (3rd month) | 250 mg of lactose/cap, 3 capsules/day | From the day before menstrual bleeding to the 3rd day of the menstrual period | Double-blind |
| Paritakul et al. (2016) [29] |
Thailand | Randomized controlled trial | Breast milk volume of postpartum women who delivered a term baby (≥37 weeks of gestation) | 15 | 0/15 | 500 mg of powdered ginger/cap, 2 capsules/day | 21 | 0/21 | 500 mg of corn starch/cap, 2 capsules/day | 7 days | Double-blind |
| Ryan et al. (2012) [30] |
United States | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 134 | 12/122 | One ginger capsule (250 mg of ginger extract) + 2 placebo capsules, twice/day | 149 | 14/135 | Three placebo capsules, twice/day | 6 days | Double-blind |
| United States | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 141 | 19/122 | Two ginger capsules (250 mg of ginger extract) + 1 placebo capsule, twice/day | ||||||
| United States | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 152 | 10/142 | Three ginger capsules (250 mg of ginger extract), twice/day | ||||||
| Zick et al. (2008) [31] |
United States | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 53 | 14/39 | 250 mg of dry ginger root extract/cap, 4 ginger capsules and 4 lactose capsules/day | 57 | 14/43 | 250 mg of lactose/cap, 8 capsules/day | 28 days | Double-blind |
| United States | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 52 | 12/40 | 250 mg of dry ginger root extract/cap, 8 capsules/day | ||||||
| Fahimi et al. (2010) [32] |
Iran | Crossover randomized controlled trial | Chemotherapy-induced nausea and vomiting | 36 | 26/10 | 250 mg of powdered ginger/cap, 2 capsules/day | 36 | 26/10 | 250 mg of lactose/cap, 2 capsules/day | 3 days for each period | Double-blind |
| Yekta et al. (2012) [33] |
Iran | Randomized controlled trial | Chemotherapy-induced nausea and vomiting | 40 | 0/40 | 250 mg of powdered ginger/cap, 4 capsules/day | 40 | 0/40 | 250 mg of starch/cap, 4 capsules/day | 6 days from three days before a chemotherapy session | Double-blind |
| Ensiyeh et al. (2009) [3] |
Iran | Randomized controlled trial | Nausea and vomiting because of pregnancy | 35 | 0/35 | 500 mg of powdered ginger/cap, 2 capsules/day | 34 | 0/34 | 20 mg of vitamin B6/cap, 2 capsules/day | 4 days | Double-blind |
| Willetts et al. (2003) [34] |
Australia | Randomized controlled trial | Nausea and vomiting because of pregnancy | 48 | 0/48 | 125 mg of ginger extract/cap, 4 capsules/day | 51 | 0/51 | 4 capsules/day, each capsule containing soya bean oil | 4 days | Double-blind |
| Vutyavanich et al. (2001) [35] |
Thailand | Randomized controlled trial | Nausea and vomiting because of pregnancy | 32 | 0/32 | 250 mg of powdered ginger/cap, 4 capsules/day | 38 | 0/38 | 4 placebo capsules/day | 4 days | Double-blind |
| Fischer-Rasmussen et al. (1990) [36] |
Denmark | Crossover randomized controlled trial | Nausea and vomiting because of pregnancy | 27 | 0/27 | 250 mg of powdered ginger root/cap, 4 capsules/day | 27 | 0/27 | 250 mg of lactose/cap, 4 capsules/day | Two periods of 4 days | Double-blind |
| Smith et al. (2004) [37] |
Australia | Randomized controlled trial | Nausea and vomiting because of pregnancy | 145 | 0/145 | 350 mg of ginger/cap, 3 capsules/day, tid | 146 | 0/146 | 25 mg of vitamin B6/cap, 3 capsules/day, tid | 3 weeks | Double-blind |
| Biswas et al. (2011) [38] |
India | Randomized controlled trial | Nausea and vomiting because of pregnancy | 34 | 0/34 | 150 mg of dried ginger extract/tab, 3 tablets/day | 29 | 0/29 | 10 mg of doxylamine + 10 mg of pyridoxine/tab, 2 or 3 tablets/day | 3 weeks | Single-blind |
| Firouzbakht et al. (2014) [39] |
Iran | Randomized controlled trial | Nausea and vomiting because of pregnancy | 24 | 0/24 | 250 mg of powdered ginger/cap, 4 capsules/day | 35 | 0/35 | 40 mg of vitamin B6/cap, 4 capsules/day | 4 days | Double-blind |
| Iran | Randomized controlled trial | Nausea and vomiting because of pregnancy | 24 | 0/24 | 250 mg of powdered ginger/cap, 4 capsules/day | 28 | 0/28 | 40 mg of sugar/cap, 4 capsules/day | 4 days | Double-blind | |
| Arfeen et al. (1995) [40] |
Australia | Randomized controlled trial | Postoperative nausea and vomiting | 36 | N/A | One capsule containing 500 mg of powdered ginger and one placebo capsule | 36 | N/A | Two placebo capsules | Single-dose | Double-blind |
| Australia | Randomized controlled trial | Postoperative nausea and vomiting | 36 | N/A | Two capsules containing 500 mg of powdered ginger | 36 | N/A | Two placebo capsules | Single-dose | Double-blind | |
| Eberhart et al. (2003) [41] |
Germany | Randomized controlled trial | Postoperative nausea and vomiting | 59 | 0/59 | 100 mg of ginger extract/cap, 1 ginger capsule + 1 placebo capsule/dose | 59 | 0/59 | 2 placebo capsules/dose | Triple dose: before operation and 3 h and 6 h post operation | Double-blind |
| Germany | Randomized controlled trial | Postoperative nausea and vomiting | 57 | 0/57 | 100 mg of ginger extract/cap, 2 ginger capsules/dose | 59 | 0/59 | 2 placebo capsules/dose | Triple dose: before operation and 3 h and 6 h post operation | Double-blind | |
| Mandal et al. (2014) [42] |
India | Randomized controlled trial | Postoperative nausea and vomiting | 50 | 42/8 | 0.5 g of powdered ginger/cap, 2 capsules/dose + 4 mg of ondansetron (i.v.) | 50 | 38/12 | 2 capsules of placebo/dose + 4 mg of ondansetron (i.v.) | 1 h before induction of general anesthesia | Double-blind |
| Ozgoli et al. (2009) [43] |
Iran | Randomized controlled trial | Primary dysmenorrhea | 50 | 0/50 | 250 mg of powdered ginger/cap, 4 capsules/day | 50 | 0/50 | 250 mg of mefenamic acid/cap, 4 capsules/day | 3 days | Double-blind |
| Iran | Randomized controlled trial | Primary dysmenorrhea | 50 | 0/50 | 250 mg of powdered ginger/cap, 4 capsules/day | 50 | 0/50 | 400 mg of ibuprofen/cap, 4 capsules/day | 3 days | Double-blind | |
| Kashefi et al. (2013) [44] |
Iran | Randomized controlled trial | Primary dysmenorrhea | 47 (1st month); 45 (2nd month) | 0/47 (1st month) 0/45 (2nd month) | 250 mg of powdered ginger/cap, 3 capsules/day | 54 (1st month); 53 (2nd month) | 0/54 (1st month); 0/53 (2nd month) | 220 mg of zinc sulfate/cap, 3 capsules/day | 4 days | N/A |
| Iran | Randomized controlled trial | Primary dysmenorrhea | 47 (1st month); 45 (2nd month) | 0/47 (1st month) 0/45 (2nd month) | 250 mg of powdered ginger/cap, 3 capsules/day | 45 (1st month); 42 (2nd month) | 0/45 (1st month); 0/42 (2nd month) | 220 mg of lactose/cap, 3 capsules/day | 4 days | N/A | |
| Rahnama et al. (2012) [45] |
Iran | Randomized controlled trial | Primary dysmenorrhea | 59 | 0/59 | 500 mg of powdered ginger root/cap, 3 capsules/day | 59 | 0/59 | 500 mg of toast powder (placebo)/cap, 3 capsules/day | From two days before the onset of menstrual period to first three days of menstrual period | Double-blind |
| Iran | Randomized controlled trial | Primary dysmenorrhea | 59 | 0/59 | 500 mg of powdered ginger root/cap, 3 capsules/day | 46 | 0/46 | 500 mg of toast powder (placebo)/cap, 3 capsules/day | First three days of the menstrual period | Double-blind | |
| Black et al. (2010) [46] |
United States | Crossover randomized controlled trial | Muscle pain, inflammation, and dysfunction induced by eccentric exercise | 27 | 12/15 | Six capsules containing 2 g of dried ginger extract with 250 mL of water and one tablespoon of olive oil. |
27 | 12/15 | Six capsules containing 2 g of flour with 250 mL of water and one tablespoon of olive oil. |
Single-dose | Double-blind |
| Black et al. (2009) [47] |
United States | Randomized controlled trial | Muscle pain caused by eccentric exercise | Raw ginger study: 17 | Raw ginger study: 3/14 | Raw ginger study: 2 g of raw ginger /day | Raw ginger study: 17 | Raw ginger study: 3/14 | Raw ginger study: 2 g of yellow cornflower/day | 11 days | Double-blind |
| United States | Randomized controlled trial | Muscle pain caused by eccentric exercise | Heat-treated ginger study: 20 | Heat-treated ginger study: 7/13 | Heat-treated ginger study: 2 g of heat-treated ginger/day | Heat-treated ginger study: 20 | Heat-treated ginger study: 7/13 | Heat-treated ginger study: 2 g of powdered brown sugar/day | 11 days | Double-blind | |
| Mahluji et al. (2013) [48] |
Iran | Randomized controlled trial | Type 2 diabetes mellitus | 28 | N/A | 1 g of powdered ginger/tab, 2 tablets/day | 30 | N/A | 1 g of corn starch/tab, 2 tablets/day | 8 weeks | Double-blind |
| Khandouzi et al. (2013) [49] |
Iran | Randomized controlled trial | Type 2 diabetes mellitus | 22 | 5/17 | 1 g of powdered ginger/cap, 2 capsules/day | 19 | 9/10 | Lactose (placebo) | 12 weeks | Double-blind |
| Phillips et al. (1992) [50] |
United Kingdom | Crossover randomized controlled trial | Gastric emptying | 16 | N/A | 500 mg of powdered ginger/cap, 2 capsules/dose | 16 | N/A | 500 mg of lactose/cap, 2 capsules/dose | Single-dose | Double-blind |
| Jiang et al. (2013) [14] |
United States | Randomized controlled trial | Normal risk for colorectal cancer | 14 | N/A | 250 mg of ginger extract/cap, 8 capsules/day | 16 | N/A | Placebo (lactose) | 28 days | Double-blind |
| United States | Randomized controlled trial | High risk for colorectal cancer | 10 | 4/6 | 250 mg of ginger extract/cap, 8 capsules/day | 10 | 3/7 | Placebo (lactose) | 28 days | Double-blind | |
| Citronberg et al. (2013) [51] |
United States | Randomized controlled trial | Cell cycle biomarkers in the normal-appearing colonic mucosa of patients at increased risk for colorectal cancer | 10 | 4/6 | 250 mg of ginger extract powder (5% gingerols)/cap, 8 capsules/day, bid | 10 | 3/7 | 250 mg of lactose powder /cap, 8 capsules/day, bid | 28 days | Double-blind |
| Zick et al. (2011) [52] |
United States | Randomized controlled trial | Eicosanoids level of patients with normal risk for colorectal cancer | 16 | N/A | 250 mg of dry ginger root extract/cap, 8 capsules/day | 17 | N/A | 250 mg of lactose/cap, 8 capsules/day | 28 days | Triple-blind |
| Zick et al. (2014) [53] |
United States | Randomized controlled trial | Eicosanoids level of patients with increased risk for colorectal cancer | 10 | 4/6 | 250 mg of dry ginger root extract (5% gingerols)/cap, 8 capsules/day | 10 | 3/7 | 250 mg of lactose/cap, 8 capsules/day | 28 days | Double-blind |
| Tilburg et al. (2014) [54] |
United States | Randomized controlled trial | Irritable bowel syndrome | 15 | N/A | 1 g of ginger in capsules (2.29 mg/g of gingerols and 6-shogaol) | 15 | N/A | Brown sugar in capsules | 28 days | Double-blind |
| United States | Randomized controlled trial | Irritable bowel syndrome | 15 | N/A | 2 g of ginger in capsules (2.29 mg/g of gingerols and 6-shogaol) | ||||||
| Wigler et al. (2003) [55] |
Israel | Crossover randomized controlled trial | Symptomatic gonarthritis | Group 1 (ginger first): 14; Group 2 (placebo first): 15 | Group 1 (ginger first): 1/13 Group 2 (placebo first): 5/10 | 250 mg of ginger extract (10 mg of gingerol)/cap, 4 capsules/day | Group 2 (placebo first): 15; Group 1 (ginger first): 14 | Group 2 (placebo first): 5/10; Group1 (ginger first): 1/13 | Placebo capsules, 4 capsules/day | Two periods of 12 weeks | Double-blind |
* DMA regimen: dexamethasone, metoclopramide, and aprepitant; M/F: Male/Female; N/A: Not available.