Scientific Name(s): Zingiber capitatum Smith., Zingiber officinale Roscoe.
Common Name(s): Black ginger, Ginger, Ginger root, Zingiberis rhizoma
Native to tropical Asia, ginger is a perennial plant cultivated in the tropical climates of Australia, Brazil, China, India, Jamaica, West Africa, and parts of the United States. The rhizome, which is used medicinally and as a culinary spice, is harvested at 6 to 20 months; taste and pungency increase with maturity. The plant carries a green-purple flower in terminal spikes, and the showy flowers are pollinated by insects.1, 2
Medicinal use of ginger dates back to ancient China and India; references to its use are found in Chinese pharmacopeias, the Sushruta scriptures of Ayurvedic medicine, and Sanskrit writings. When its culinary properties were discovered in the 13th century, use of this herb became widespread throughout Europe. In the Middle Ages, apothecaries recommended ginger for travel sickness, nausea, hangovers, and flatulence.
Ginger is found in the official pharmacopeias of Austria, China, Egypt, Great Britain, India, Japan, the Netherlands, and Switzerland. It is approved as a nonprescription drug in Germany and as a dietary supplement in the United States.2, 3, 4
Only unbleached ginger (scraped or unscraped) is accepted as a medicinal-grade drug, containing 1.5% or more volatile oil. Quality standards for ginger can be found in the United States Pharmacopeia.
More than 400 different compounds have been identified in ginger. The major constituents in ginger rhizomes are carbohydrates (50% to 70%), which are present as starch. The concentration of lipids is 3% to 8% and includes free fatty acids (eg, palmitic, oleic, linoleic, linolenic, capric, lauric, myristic), triglycerides, and lecithins. Oleoresin provides 4% to 7.5% of pungent substances as gingerol homologues, shogaol homologues, zingerone, and volatile oils. Volatile oils are present in 1% to 3% concentrations and consist mainly of the sesquiterpenes beta-bisabolene and zingiberene; other sesquiterpenes include zingiberol and zingiberenol. Numerous monoterpenes are also present. Amino acids, raw fiber, ash, protein, phytosterols, vitamins (eg, nicotinic acid, vitamin A), and minerals are among the other constituents.
Analyses of the oleoresins have resulted in the identification of a class of structurally related compounds called gingerols, which form shogaols and degrade further to zingerone when dehydrated. The main components are -gingerol and -shogaol; however, the pharmacologically active compounds - and -dehydrogingerdione and - and -gingerdione have also been identified.1, 5, 6, 7, 8, 9
Uses and Pharmacology
The ginger rhizome is a widely used culinary spice. The relative safety of ginger and the availability of randomized clinical trials in humans render data from animal trials largely irrelevant for some indications.
Results from published studies are equivocal, and several trials are compromised by methodological flaws.6, 12, 13, 14 Ginger 2 g/day over 11 days was effective in reducing exercise-induced muscle pain; however, markers of prostaglandin synthesis were unaffected, and a single dose was ineffective.15, 16 A randomized, double-blind, placebo-controlled trial in 20 non–weight-trained adults found that ginger supplementation (4 g/day × 5 days) significantly improved muscle recovery in the early stages after exercising (24 to 48 hours) (P = 0.002) but not 72 or 96 hours after exercising, in contrast to placebo. Additionally, ginger appeared to increase indicators of muscle damage, as pairwise comparisons revealed significant increases in overall creatine kinase (P = 0.01) and impaired flexibility (P < 0.005).86 A systematic review and meta-analysis of 8 randomized clinical trials (N = 734) published before December 2014 found an overall moderate to large effect of Zingiberaceae extracts (including turmeric, ginger, and galangal) on chronic pain compared with placebo; however, substantial heterogeneity was found. Significantly lower subjective pain was reported with the intervention (P = 0.004). A strong dose-response relationship was also demonstrated. Patient groups included 3 studies in patients with osteoarthritis of the knee or hip, and 1 study each in patients with gonarthritis, irritable bowel syndrome, muscle soreness following exercise, postoperative pain, and primary dysmenorrhea. The 4 trials that used ginger monotherapy (n = 315) used doses of ginger rhizome extract or powder ranging from 510 mg/day to almost 2 g/day over a period of 3 days to 3 months.89 In 100 patients with knee osteoarthritis, 3 months of supplementation with ginger (500 mg twice daily) resulted in a significant reduction in the proinflammatory cytokines TNF-alpha and IL-1beta (P<0.001 each) compared to baseline and placebo. The study was a double-blind, randomized, placebo-controlled design conducted in patients 50 to 70 years of age.95
Limited studies suggest ginger is effective in reducing dysmenorrhea when administered at 500 mg 3 times daily either at the onset of menses or 2 days earlier. A few studies have demonstrated ginger to be as effective as mefenamic acid or ibuprofen in women with primary dysmenorrhea.17, 18, 19, 84 In another randomized, placebo-controlled, double-blind trial conducted in Iranian high school females (N = 150) with primary dysmenorrhea and a pain score higher than 4 on the visual analog scale, reduction in pain was significant in the ginger (250 mg 3 times daily) and zinc sulfate (220 mg 3 times daily) groups compared with placebo (P < 0.001). Interventions were taken for 4 days: the day before menstruation and for the next 3 days. Adverse effects were not significantly different among groups.83 These data have been supported by results of a meta-analysis evaluating the effectiveness of ginger (750 to 2,000 mg for the first 3 to 4 days of menstruation) for treating primary dysmenorrhea in females 13 to 30 years of age. Of the 7 trials included in the analysis, 4 randomized clinical trials (N = 366) provided efficacy data for ginger versus placebo and demonstrated a significant reduction with ginger (P = 0.0003).85 A Cochrane systematic review and meta-analysis of dietary supplements for dysmenorrhea identified only low or very low quality studies with very small sample sizes. Very limited evidence of effectiveness was found for the treatment of primary dysmenorrhea with ginger powder 500 to 750 mg/day compared to placebo or no treatment (4 randomized clinical trials, N = 335); however, no difference was identified between ginger 250 mg 3 times daily and zinc sulfate 220 mg 3 times daily (1 randomized clinical trial, n = 101). No adverse events from ginger supplementation were observed.90
Anti-tuberculosis drug–induced hepatotoxicity
In a double-blind, randomized, controlled trial (n=69), newly diagnosed and treatment-naive tuberculosis patients received 500 mg/day of ginger (1.62 mg/day of 6-gingerol and 0.64 mg/day of 6-shogaol) or placebo for 4 weeks. Interventions were administered 30 minutes prior to morning anti-tuberculosis medications; medications usually used for controlling tuberculosis drug-induced GI adverse effects, including nausea and vomiting, were omitted during the study period. Administration of ginger significantly reduced the anti-tuberculosis drug-induced frequency of nausea compared to placebo (P=0.001); however, no difference was found between groups for frequency of vomiting, abdominal pain, or hepatotoxicity. Factors that were significantly associated with anti-tuberculosis drug-induced hepatotoxicity included serum albumin less than 3.5 mg/dL, injection drug use, diabetes mellitus, and co-infections with HIV and hepatitis C virus. Mild heartburn occurred in 10% (n=3) of the ginger-treated patients, which was tolerable within 1 week of continuing treatment.94
Antitumor activity of ginger and its constituents has been demonstrated in several in vitro and animal experiments. Apoptotic cell death and antiproliferative effects caused by gingerol, paradol, shogaol, essential oil of ginger, and dried homogenized ginger have been demonstrated in mice and in human cell lines.6, 20, 21, 22
No human trials using ginger in cancer treatment have been published.20, 22 A pilot trial reported findings after evaluating the efficacy of ginger root extract in decreasing eicosanoids as a marker of colorectal cancer risk.23 Results from another pilot randomized controlled trial that evaluated effects of ginger supplementation on cell-cycle biomarkers suggested that 2 g of ginger daily for 28 days may reduce proliferation in normal-appearing colonic mucosa of patients at increased risk of colorectal cancer as well as increase apoptosis and differentiation relative to proliferation.71
A randomized, double-blind, placebo-controlled trial conducted in patients who had type 2 diabetes mellitus for at least 10 years (n = 88) found a significant improvement in mean fasting blood glucose (FBS; 10.5%) in the ginger group compared with a significant increase in FBS in the placebo group (21%) (P = 0.01). Additional insulin resistance indices that were statistically significantly improved with ginger included fasting insulin level, insulin sensitivity, and homeostasis model assessment (HOMA) (P < 0.005).78 Similarly, 63 adult patients with type 2 diabetes mellitus who completed a 12-week intervention of ginger (1,600 mg/day) in a double-blind, randomized, controlled trial, experienced significantly improved changes in fasting plasma glucose (P = 0.02), glycated hemoglobin (HbA1c) (P = 0.001), insulin (P = 0.01), HOMA (P = 0.000), triglycerides (P = 0.001), total cholesterol (P = 0.02), high-density lipoprotein/total cholesterol ratio (P = 0.02), serum C-reactive protein (P = 0.01), and PGE2 (P = 0.000). No significant changes were noted between groups with regards to body mass index or body weight.79 Similar effects on glycemic markers were found in a double-blind, randomized, placebo-controlled trial in 50 Iranian adults with a body mass index up to 30 who had type 2 diabetes for mean duration of approximately 5 years. Ginger 3 g/day was provided for 3 months. Compared with placebo and baseline, significant improvements were observed in serum glucose, HbA1c, insulin, insulin resistance, malondialdehyde, high-sensitive C-reactive protein, total antioxidant capacity, and paraoxonase-1. Oral medications given during the trial included metformin, glibenclamide, or both to control blood sugar.88
Gastrointestinal, irritable bowel syndrome
Disease severity and symptom relief of irritable bowel syndrome was not found to be significantly different between placebo and 1 or 2 g/day of ginger in a 28-day randomized, controlled, parallel group study (n = 45). However, pre- and posttreatment severity scores were significantly improved in both the placebo (P = 0.001) and ginger 1 g/day groups (P = 0.007); significant symptom improvement was experience by 34.8% and 26.4%, respectively. Mild side effects were reported and were more common in the placebo group (35.7%) than the ginger group (16.7%).77
Gout, acute attack
The American College of Rheumatology guidelines on the management of gout (2012) voted that the use of various oral complementary agents, including ginger, was inappropriate for the treatment of an acute attack of gout.68
Heavy menstrual bleeding
Administration of freshly prepared ginger capsules (250 mg 3 times daily) significantly reduced blood loss in Iranian teenage high school girls who experienced heavy menstrual bleeding. In a placebo-controlled, double-blind, randomized trial, mean hemorrhage within the ginger-treated group decreased by 46.6% (mean, 113.73 mL to 60.67 mL) during the 3 intervention months compared with the 3 pre-intervention assessment months (P < 0.001). Additionally, the percent reduction in mean bleeding was significantly different between the ginger (46.6%) and placebo (2.1%) groups (P < 0.001).82
A randomized, double-blind, placebo-controlled trial (n = 100) comparing efficacy of ginger and sumatriptan in treating migraine without aura found the 2 agents equally effective. Within 2 hours of taking ginger (250 mg ginger rhizome powder) or sumatriptan (50 mg), patients experienced at least a 90% reduction in headache severity.74
Animal studies have described enhanced GI transport, anti-5-hydroxytryptamine, and possible CNS antiemetic effects. It has been theorized that the mode of administration, due to gingerol and shogaol effects on GI motility, depends on route.1
Human experiments to determine the mechanism of action show varying effects on gastric motility, antral contractions, and corpus motor response.24, 25, 26, 27, 28 No impact on GI symptoms and gut peptides, and no change in measurements of fundus dimensions have been shown.29, 30, 31 The influence of gender and supplemental information has been examined by some researchers evaluating the effect of ginger on motion sickness.32 A case report describes a reduction in disequilibrium and nausea associated with abrupt discontinuation or intermittent noncompliance with selective serotonin reuptake inhibitors (ginger 1 g given 3 times daily).33
Antiretroviral-induced nausea and vomiting
Ginger (500 mg twice daily) administered 30 minutes prior to antiretroviral therapy for 2 weeks, significantly reduced antiretroviral-induced nausea and vomiting. The total number of patients experiencing any nausea was 56.9% vs 90.2% for ginger and placebo, respectively (P = 0.001). Frequency of nausea was also significantly lower with ginger (mild [P = 0.02]; moderate [P = 0.04]; severe [P = 0.001]). Additionally, 9.8% in the ginger group vs 47.1% in the placebo group experienced at least 1 episode of vomiting (P = 0.01). The most common antiretroviral regimen was efavirenz and lamivudine plus zidovudine (97%).81
Results from published studies are equivocal.34, 35, 36, 37, 38 A meta-analysis published in 2013 including 5 clinical trials, with a total of 872 participants, reported that evidence does not support the use of ginger for reducing short-term nausea (P = 0.12) or short-term vomiting (P = 0.37,), nor severity of short-term nausea (P = 0.12).36 A large (N = 576), multicenter trial not included in the meta-analysis found a decrease in nausea, but not vomiting, when ginger 0.5 to 1 g daily was added to standard management (5-HT3 receptor antagonists and dexamethasone).39 A single-blind, randomized, controlled crossover trial examined the effect of inhaled ginger aromatherapy on chemotherapy-induced nausea and vomiting in 60 adult female breast cancer patients in Malaysia. For 5 days, ginger essential oil vapors or placebo were inhaled at least 3 times daily for a 2-minute minimum duration at each inhalation regardless of if symptoms were present. A significant reduction in nausea and vomiting incidence (P < 0.001 each) was seen only in the acute phase (day 2) and was not sustained over the 5 days of therapy. However, significant improvements were observed in 6 health-related quality of life subscores for some patients, including: global health status, role functioning, fatigue, nausea and vomiting, pain, appetite loss, and constipation. No major adverse events were observed.87 Similarly, powdered ginger 500 mg twice daily taken orally 30 minutes prior to chemotherapy for 3 days by women with stage II or III breast cancer was found to produce a statistically significant reduction in nausea severity and number of vomiting/retching episodes on days 2 to 5 compared to controls in a randomized controlled trial (n=60). Five-day mean scores for both of these outcomes were also statistically significantly lower in the ginger group than controls (P<0.05). However, the number of vomiting/retching episodes did not differ significantly from baseline.91 In contrast, ginger (500 mg twice daily) given during adriamycin-cyclophosphamide or cisplatin-based chemotherapy did not provide any benefit compared to placebo in chemotherapy-induced nausea or vomiting in 34 women with breast cancer or 140 patients with lung cancer enrolled in double-blind, randomized, placebo-controlled trials. Additionally, no significant difference was observed in the rate of rescue medication use. No treatment-related adverse effects were observed.96, 99
An American Society of Clinical Oncology clinical practice guideline update (2011) for antiemetic use associated with chemotherapy discussed a phase 3 placebo-controlled study that reported no significant differences in the prevalence of vomiting and nausea between patients who received ginger and placebo. These guidelines further stated that there are no published randomized controlled trial data available regarding alternative and complementary medicines that met inclusion criteria to support a recommendation about such therapies.69
Results from published trials and meta-analyses are equivocal. Limitations of meta-analyses include lack of comparators, heterogenous study populations, and varying surgical procedures.40, 41 In a 2006 meta-analysis of 5 randomized clinical trials investigating the efficacy of ginger in postoperative nausea, ginger 1 g was more effective than placebo (relative risk, 0.69; confidence interval, 0.54 to 0.89).41 Other reviews and meta-analyses, some including trials excluded by others, did not find ginger useful in the postoperative setting; the numbers needed for effect range from 11 to 25.6 The Society of Obstetricians and Gynaecologists of Canada (SOGC) guidelines for the management of postoperative nausea and vomiting (2008) note that although ginger root is a commonly used nonmedical therapy, it is not effective for postoperative nausea and vomiting prophylaxis.70 Data from a 2013 double-blind, placebo-controlled, randomized clinical trial in 239 full-term parturients undergoing elective C-section are congruent with the SOGC guidelines. Although the number of episodes of intraoperative nausea were significantly reduced, no effect was found overall on intraoperative or postoperative nausea and vomiting in women administered dry powder ginger capsules versus placebo.73
A 2012 randomized, placebo-controlled trial in 1,151 patients who reported nausea in postanesthesia care found a statistically significant reduction in nausea level and the number of antiemetic medications requested after essential oil of ginger as well as a blend of ginger, spearmint, peppermint, and cardamom essential oils were administered as aromatherapy. Postoperative nausea improved almost 2 to 1 with ginger versus saline, and almost 3 to 1 with the blend versus saline.72 The Society for Ambulatory Anesthesia consensus guidelines (2014) note ginger as a possible alternative therapy in preventing postoperative nausea and vomiting in adults at moderate risk. Data from a recent meta-analysis found an oral 1 g dose of ginger to be more effective than placebo, although earlier meta-analyses found ginger to be ineffective (high-quality evidence).75
Results from limited published high-quality studies are equivocal. Ginger appears to be more efficacious than placebo in reducing nausea, but equal or less than metoclopramide and vitamin B6. No effect on vomiting was demonstrated in these trials.41, 42, 43, 44, 45, 46 However, a meta-analysis of 6 randomized clinical trials showed 1 g/day of ginger for at least 4 days to be better than placebo at reducing pregnancy-related nausea and vomiting (pooled odds ratio, 4.89; P < 0.0001).76 A subsequent systematic review and meta-analysis built upon the previous review by including 6 additional randomized controlled trials and also by parsing out data for each unique comparator (placebo, dimenhydrinate, metoclopraminde, and vitamin B6). The data indicated that ginger significantly decreased pregnancy-related nausea compared with placebo (P = 0.0002) but not compared with vitamin B6; subgroup analysis favored efficacy for doses less than 1,500 mg daily. No significant difference was seen in the number of vomiting episodes between ginger and placebo or vitamin B6. No significant difference was observed between ginger and metoclopramide for severity of nausea or vomiting; no efficacy results could be calculated for the ginger–dimenhydrinate study. Ginger was well tolerated; it caused less drowsiness than dimenhydrinate and more belching than vitamin B6.80
Little information on fetal outcomes has been published in relation to clinical trials investigating the use of ginger in pregnancy, and studies have generally been too small to detect abnormalities.43, 45
The American College of Obstetrics and Gynecologists (ACOG) practice guideline for nausea and vomiting of pregnancy (2018) recommend the consideration of ginger as a nonpharmacologic treatment option for the reduction of nausea (Level B).97
Inhibition of platelet aggregation
Studies from animal models are inconclusive, but experiments with different ginger extracts have suggested antiaggregation effects.6
Results in human experiments are inconclusive. Ginger demonstrated an inhibitory effect in 1 study and, in another, no effect on platelet aggregation at recommended daily doses (less than 5 g).1, 47, 48
Clinical studies have found equivocal effects on the lipid profile.49, 50 A small double-blind, randomized, placebo-controlled trial conducted in 38 patients on continuous ambulatory peritoneal dialysis found a significant decrease only in serum triglycerides compared to baseline and placebo in patients who consumed ginger 1,000 mg/day for 10 weeks. No significant changes were documented in serum total cholesterol, low-density lipoprotein cholesterol, or lipoprotein(a). However, high-density lipoprotein cholesterol was noted to be significantly decreased compared to baseline in the placebo group but not in the ginger group.92 Similarly, a 2018 systematic review and meta-analysis of 12 placebo-controlled clinical trials (N=586) found the administration of ginger to have significant overall effects on triacylglycerol (−17.59 mg/dL, P=0.003) and LDL (−4.9 mg/dL, P=0.02) but not total cholesterol or HDL, however significant heterogeneity was observed for each of these meta-analyses. Subgroup analysis among trials without significant heterogeneity identified significant improvements only in total cholesterol for ginger given for less than 50 days duration (−9.78 mg/dL, P=0.007), in triacylglycerol for ginger doses greater than 2 g/day (−10.41 mg/dL, P=0.014), and for LDL in low-quality studies (−6.99 mg/dL, P=0.019).100
Ginger is commonly used in combination in traditional remedies, including sho-saiko-to-ka-kikyo-sekko in tonsillitis, tongyan spray in dysphagia, and the Kampo medicine daikenchuto.52, 53, 54 A one-time dose of 1% ginger orally disintegrating tablets (2 mg ginger powder/tablet) was shown to significantly increase the amount of salivary substance P in elderly individuals (P<0.05); low secretion of salivary substance P has been noted as the cause of dysphagia.93 It has also been used in clinical studies with lavender oil as an anxiolytic, with feverfew in migraine, and in combination with Tinospora cordifolia in rheumatoid arthritis.55, 56, 57
Ginger as an adjunctive agent has been studied in individuals 8 to 21 years of age for chemotherapy-related nausea at dosages of 1 and 2 g/day.38
Pregnancy / Lactation
Avoid use.22, 58, 59 Despite the availability of clinical trials investigating the use of ginger in pregnancy-related nausea, data on fetal outcomes are lacking.22, 43 One animal study showed early embryo loss, while no effect was found in another.22 Chemical constituents of ginger possess apoptotic effects in human lymphoma cells.6, 20, 21, 22 Ginger affects protein binding of testosterone, which has led to concerns related to the embryo development.22 In the Complete German Commission E Monographs, ginger is contraindicated for use in morning sickness.4
Agents with antiplatelet properties: Herbs (anticoagulant/antiplatelet properties) may enhance the adverse/toxic effect of agents with antiplatelet properties. Bleeding may occur. Consider therapy modification.60, 61, 62, 63
Herbs (anticoagulant/antiplatelet properties): May enhance the adverse/toxic effect of other herbs (anticoagulant/antiplatelet properties). Bleeding may occur. Consider therapy modification.60, 61, 62, 63
Hypoglycemic agents: Herbs (hypoglycemic properties) may enhance the hypoglycemic effect of hypoglycemic agents. Monitor therapy.66
Nonsteroidal anti-inflammatory agents: Herbs (anticoagulant/antiplatelet properties) may enhance the adverse/toxic effect of nonsteroidal anti-inflammatory agents. Bleeding may occur. Consider therapy modification.60, 61, 62, 63
The FDA lists ginger as GRAS.67 In culinary quantities, the root is generally devoid of activity, although larger doses carry the potential for adverse reactions. Adverse reactions reported in trials are uncommon and include mild GI effects (eg, heartburn, diarrhea, mouth irritation).6, 12 Case reports of arrhythmia and IgE allergic reaction have been documented.6, 12
Toxicological information regarding the use of ginger in humans is limited, and mutagenicity is contested.1, 6, 22 The median lethal dose of ginger oil has been estimated to be more than 5 g/kg of body weight in rats.6 Teratogenicity studies reported that rat fetuses exposed to high-dose ginger tea were heavier and had more advanced skeletal development than controls. Embryonic loss was greater in the treatment group. In another similar study with different types of rats, no teratogenicity was observed.6, 22
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