Encyclopedia of

Ginger (Zingiber officinale) 245
the knee as diagnosed by the American College of
Rheumatology classification criteria. [35] The primary
efficacy variable was the proportion of responders
experiencing a reduction in ‘‘knee pain on standing,’’
using an intent-to-treat analysis. A responder was
defined by a reduction in pain of 15 mm on a visual
analog scale. During the 6-week treatment period,
patients ingested 1 capsule twice daily of 255 mg
ginger extract (EV.EXT 77, extracted from 2500–
4000 mg of dried ginger rhizomes and 500–1500 mg
of dried galanga rhizomes) or placebo. The percentage
of responders experiencing a reduction in knee pain
on standing was superior in the ginger extract group
compared with the control group (63% vs. 50%;
p ¼ 0.048). Analysis of the secondary efficacy variables
revealed a consistently greater response in the
ginger extract group compared with the control
group, when analyzing mean values: reduction in
knee pain on standing (24.5 vs. 16.4 mm; p ¼ 0.005)
and reduction in knee pain after walking 50 ft (15.1
vs. 8.7 mm; p ¼ 0.016). One group of adverse events
showed a significant difference between treatment
groups: Gastrointestinal (GI) adverse events were
more common in the ginger extract group [116 events
in 59 patients (45%)] compared with the placebo
group [28 events in 21 patients (16%)]. None of the
GI adverse events were considered serious by the
investigators.
Both of these studies suggest the strong need for
dose escalation studies that can determine the most
efficacious dose that it is still safe and well tolerated.
Studies of longer duration are also required before
more definitive conclusions can be drawn about the
safety, tolerance, and effectiveness of ginger for
osteoarthritis.
Cardiovascular Effects
In vitro research has shown that constituents in ginger
have an inhibitory effect upon cholesterol biosynthesis.
[36] Animal studies have demonstrated lipidlowering
activity via enhancement of the activity of
hepatic cholesterol-7a-hydroxylase, the rate-limiting
enzyme in bile acid biosynthesis, thereby stimulating
conversion of cholesterol to bile acids, an important
mechanism for eliminating cholesterol from the
body. [37] A study in rabbits found that an orally administered
ethanolic extract of ginger (200 mg=kg) reduced
lipids after 10 weeks feeding of a cholesterol rich
diet. The authors found that, at this dose, ginger
produced results similar to those of gemfrimbrozil. [38]
In contrast to the in vitro and animal data, a study of
patients with coronary artery disease found that 3 mo
ingestion of 4 g=day dried ginger powder failed to
lower blood lipids. [39]
Ginger inhibits platelet aggregation in vitro, acting
as a potent inhibitor of arachidonic acid, epinephrine,
adenosine diphosphate (ADP), and collagen. A
placebo-controlled study of 8 healthy males found
that ingestion of 2 g of ginger caused a dose-dependent
reduction of thromboxane synthetase and prostaglandin
synthetase; however, no differences were
found in bleeding time, platelet count, or platelet
function between the placebo and control groups. [40]
In patients with coronary artery disease (CAD),
powdered ginger administered in a dose of 4 g=day
for 3 mo did not affect ADP- and epinephrine-induced
platelet aggregation. However, a single dose of 10 g
produced a significant reduction in platelet aggregation
induced by the two agonists. [39]
Gastrointestinal Effects
Ginger has long been valued in traditional medicine
for a wide variety of gastrointestinal complaints.
Researchers are beginning to explore possible scientific
explanations for these historical uses. In vitro research
indicates that constituents present in ginger have
antiulcer activity. [41] Animal research demonstrates
that ginger reduces the occurrence of gastric ulcers
induced by nonsteroidal anti-inflammatory drugs
(NSAIDs) and hypothermic restraint stress. [42] Cholagogic
activity has been documented in rats with the
acetone extract of ginger. [43]
Helicobacter pylori (HP) is the primary etiological
agent associated with dyspepsia, peptic ulcer disease,
and development of gastric cancer. Novel, inexpensive,
and safe approaches to the eradication of H. pylori
are currently being sought. A methanol extract of
the dried, powdered ginger rhizome, fractions of the
extract, and the isolated constituents, 6-, 8-, and 10gingerol
and 6-shogaol, were tested against 19 strains
of HP. [44] The extract inhibited the growth of all 19
strains in vitro with a minimum inhibitory concentration
(MIC) range of 6.25–50 mg=ml. One fraction of
the crude extract, containing the gingerols, was active
and inhibited the growth of all HP strains with a
MIC range of 0.78–12.5 mg=ml.
DOSE
As with many botanicals, dosage ranges vary widely
in research and, especially, in the marketplace. The
following are a few doses (serving sizes) found in the
literature:
Fresh or dried rhizome: 2–4 g daily. [45]
Fluidextract: 1 : 1(g=ml) 0.25–1.0 ml 3 times daily;
tincture 1 : 5(g=ml) 1.25–5.0 ml 3 times daily. [45]
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