Does ginger relieve nausea and help digestion?

Fresh ginger's pungent taste comes primarily from 6-gingerol, the most abundant bioactive compound in the raw rhizome. When ginger is dried, heated, or processed, gingerols convert into shogaols. Dried ginger and fresh ginger therefore have different compound profiles. Reviews attribute ginger's health effects to gingerols, shogaols, and paradols, and the evidence for specific actions of each compound in people is still limited³.

Nausea: Where the Evidence Is Strongest and Weakest

Pregnancy Nausea

A meta-analysis of 12 randomized controlled trials involving 1,278 pregnant women found that ginger significantly improved the symptoms of nausea compared with placebo (mean difference 1.20, 95% CI 0.56 to 1.84). It did not significantly reduce the number of vomiting episodes, though there was a trend toward improvement. Analyses by dose seemed to favor lower daily amounts (under 1,500 mg) for nausea relief. Ginger did not pose a significant risk of spontaneous abortion compared with placebo or vitamin B6, nor of heartburn or drowsiness. The authors rate the evidence low quality, given the limited number of studies and variable outcome reporting, and say ginger could be considered a harmless and possibly effective alternative option for women with pregnancy nausea².

Other Types of Nausea

A systematic review of six randomized trials found that results differ by setting¹. Of three trials of postoperative nausea and vomiting, two suggested that ginger was better than placebo and as effective as metoclopramide, but a pooled analysis of the incidence of postoperative nausea found no significant difference between ginger (1 g before the operation) and placebo. There was one trial each for seasickness, morning sickness, and chemotherapy-induced nausea, and together these favored ginger over placebo¹. Single small trials are not enough to say how well ginger works for chemotherapy-related or motion-related nausea.

Digestive Aid: Gastric Motility

Beyond nausea, ginger affects how fast the stomach empties. In a randomized, double-blind crossover study in 24 healthy volunteers, those who took three ginger capsules (1,200 mg in total) emptied their stomachs of a test soup about twice as fast as with placebo, and the antral muscle of the stomach contracted more often⁴. Ginger did not change any gastrointestinal symptom scores in these healthy volunteers. The authors suggest the effect could be beneficial in patients with symptoms, but this study did not test that.

This effect may help explain why many cultures traditionally use ginger before or during meals — as a digestive "starter" in the form of pickled ginger, ginger tea, or fresh slices.

Anti-Inflammatory and Antioxidant Effects

A review of the literature from 2000 to 2010 concluded that the evidence favors ginger as an anti-inflammatory and antioxidant, and it describes gingerol, shogaol, and paradol as valuable ingredients, but it also says that some ambiguities need further research before ginger's efficacy can be claimed³. The anti-inflammatory effects pair with turmeric in traditional medicine; see the Turmeric page.

Blood Sugar Regulation

Emerging research suggests ginger may support glycemic control in type 2 diabetes. In a randomized, double-blind, placebo-controlled trial in 41 patients, 2 g a day of ginger powder for 12 weeks significantly lowered fasting blood sugar, HbA1c, apolipoprotein B, and malondialdehyde compared with baseline and with placebo, and raised apolipoprotein A-I⁵. It was a small trial from one group, so it needs confirmation, and ginger should not replace diabetes medication.

Nausea: Systematic Review

Ernst and Pittler (2000) in the British Journal of Anaesthesia (PMID 10793599) systematically reviewed randomized trials of ginger for nausea and vomiting, finding six that met their inclusion criteria¹. Three concerned postoperative nausea and vomiting; two of these suggested that ginger was superior to placebo and as effective as metoclopramide. The pooled absolute risk reduction for the incidence of postoperative nausea, however, indicated a non-significant difference between ginger and placebo for 1 g taken before operation (absolute risk reduction 0.052, 95% CI −0.082 to 0.186). One study was found for each of seasickness, morning sickness, and chemotherapy-induced nausea, and these collectively favored ginger over placebo. The authors framed the question as still a matter of debate.

Pregnancy Nausea Safety and Efficacy

Viljoen et al. (2014) in Nutrition Journal (PMID 24642205) searched for randomized trials of orally administered ginger as treatment for pregnancy-associated nausea and vomiting and included 12 RCTs with 1,278 pregnant women². Ginger significantly improved nausea symptoms compared with placebo (MD 1.20, 95% CI 0.56 to 1.84, p = 0.0002, I² = 0%). It did not significantly reduce vomiting episodes (MD 0.72, 95% CI −0.03 to 1.46, p = 0.06, I² = 71%). Subgroup analyses seemed to favor the lower daily dosage (under 1,500 mg) for nausea relief. Ginger did not pose a significant risk for spontaneous abortion compared with placebo (RR 3.14, 95% CI 0.65 to 15.11, p = 0.15) or with vitamin B6 (RR 0.49, 95% CI 0.17 to 1.42, p = 0.19), nor for heartburn or drowsiness. The reviewers caution that the number of studies was limited, outcome reporting varied, and the quality of evidence was low.

Anti-Inflammatory Mechanisms

Mashhadi et al. (2013) in the International Journal of Preventive Medicine (PMID 23717767) searched MEDLINE for publications from 2000 to 2010 on ginger and anti-oxidative or anti-inflammatory effects³. The review notes that the anticancer potential of ginger is well documented and that its functional ingredients, such as gingerols, shogaol, and paradols, are valuable ingredients that may help prevent various cancers. It concludes in favor of ginger but states that some ambiguities require further research before claiming its efficacy.

Gastric Emptying

Wu et al. (2008) in the European Journal of Gastroenterology & Hepatology (PMID 18403946) studied 24 healthy volunteers twice in a randomized, double-blind manner⁴. After an 8-hour fast, volunteers took three ginger capsules (1,200 mg total) or placebo, and 1 hour later drank 500 mL of low-nutrient soup. Ultrasound was used to measure antral area, fundus area and diameter, and the frequency of antral contractions over 90 minutes, and the gastric half-emptying time was calculated. Antral area decreased more quickly (P < 0.001) and the gastric half-emptying time was shorter after ginger than placebo (13.1 ± 1.1 vs. 26.7 ± 3.1 minutes, P < 0.01), while the frequency of antral contractions was greater (P < 0.005). Fundus dimensions did not differ and there was no significant difference in any gastrointestinal symptom. The authors concluded that ginger accelerates gastric emptying and stimulates antral contractions in healthy volunteers and that these effects could potentially be beneficial in symptomatic patient groups.

Blood Sugar Effects

Khandouzi et al. (2015) in the Iranian Journal of Pharmaceutical Research (PMID 25561919) conducted a randomized, double-blind, placebo-controlled trial of 2 g a day of ginger powder in 41 patients with type 2 diabetes (22 given ginger, 19 given lactose placebo) for 12 weeks⁵. Fasting blood sugar, HbA1c, apolipoprotein B, the apolipoprotein B to A-I ratio, and malondialdehyde (an oxidative-stress marker) were significantly reduced in the ginger group compared with baseline and with the control group, and apolipoprotein A-I rose (p < 0.05). The sample was small, and the authors suggest only that ginger may have a role in lowering the risk of some chronic complications of diabetes.

Summary

The best-supported use of ginger is for nausea in pregnancy, where a meta-analysis of 12 trials found improved nausea (not vomiting) with low-quality evidence and no excess risks found for the outcomes assessed². For other kinds of nausea the evidence comes from single small trials or from analyses that showed no significant effect¹. Ginger speeds stomach emptying in healthy volunteers⁴, and the blood sugar findings come from one small trial⁵.