Ginger, the underground stem, or rhizome, of the plant Zingiber officinale has been used as a medicine in Asian, Indian, and Arabic herbal traditions since ancient times. Among other maladies, it has been used to treat stomach upset and nausea, as well as headache and arthritis pain. Christopher Black, PhD, and colleagues at the University of Georgia conducted a trial to examine the benefits of either raw (study 1) or heat-treated (study 2) ginger supplementation for relieving exercise-induced muscle pain [Black et al. 2010].
Studies 1 and 2 were identical double-blind, placebo controlled, randomized experiments involving 34 and 40 healthy volunteers, respectively. Participants consumed 2 grams of either the raw (study 1) or heat-treated (study 2) ginger or placebo during each of 11 consecutive days. On day 8 of the study subjects performed a weight-lifting exercise designed to strain elbow flexor muscles (eg, biceps), thereby inducing pain and inflammation. Pain intensity, perceived effort, plasma prostaglandin E2, arm volume, range-of-motion, and isometric strength were assessed prior to and for 3 days after exercise (days 9 to 11).
Both the raw and heat-treated ginger produced equivalent and statistically significant reductions in pain (about 25% and 23%, respectively) compared with placebo within 1 day (24 hours) following the exercise task; however, no significant differences were noted at the assessments 48- and 72-hours post-exercise. Smaller effects were noted between both types of ginger and placebo on other measures. The authors conclude that daily supplementation with ginger reduces exercise-induced muscle pain, and this effect is not enhanced by heat treating the ginger.
COMMENTARY: This study by Black et al. was funded by the McCormick Science Institute, a research arm of food seasoning producer McCormick & Co., Inc. The trial was well-designed and meticulously executed to control for confounding variables; however, there are a number of concerns — completely overlooked or misunderstood in news media reports — that limit the external validity of results and could curb one’s enthusiasm for recommending ginger supplements for analgesic purposes:
- Subjects recruited for the study were healthy college men and women (ages 21-23) and the results may not apply to older persons and/or those with preexisting musculoskeletal pain conditions.
- Group sizes were small (17 to 20 subjects each) and levels of pain after exercise were moderate (less than 40 on a 0 to 100 scale). The observed decreases in pain attributed to ginger consumption (up to 25%) were statistically significant but possibly not clinically meaningful.
- The particular raw ginger root used for the study was freshly imported from India and the supplement capsules were carefully prepared to exacting standards. Each capsule contained on average one-third gram of ginger, so trial participants consumed 6 capsules at one time each day. Commercially available ginger capsules, being uncontrolled nutritional supplements, come from various countries and may contain differing amounts of biologically active chemicals, such as gingerols and shogaols. Also, commercial ginger supplements, which often come in 540 mg or 550 mg capsules, range widely in cost (though most are inexpensive), which may or may not be indicative of varying quality that could impact their potency and effectiveness.
- The current study by Black and colleagues used a loading dose of 2 grams of ginger supplements per day for 8 days prior to the pain-inducing exercise; however, in an earlier study by these researchers subjects did not take the ginger supplement until 24 hours after exercise and then again at 48 hours post-exercise; this approach demonstrated no benefits in reducing pain compared with placebo [Black and O’Connor 2008]. Therefore, ginger supplements apparently must be taken for some period of time before any analgesic effects can be realized. For example, Black et al.  mention a series of randomized controlled trials in which 4 to 36 weeks of daily consumption of 30 to 500 mg of ginger extract preparations resulted in reduced hip and/or knee pain in patients with osteoarthritis.
> Black CD, Herring MP, Hurley DJ, O’Connor PJ. Ginger (Zingiber officinale) reduces muscle pain caused by eccentric exercise. J Pain. 2010; online ahead of print [abstract here].
> Black CD, O’Connor P. Short term effects of 2-grams of dietary ginger on muscle pain, inflammation and disability induced by eccentric exercise. Abstract 197. J Pain. 2008(Apr);9(4, Suppl 2):25.
> Ehrlich SD. Ginger. University of Maryland Medical Center. 2008(Nov) [available here].