Cat's Claw
Uses
Principal Proposed Uses
Other Proposed Uses
-
What Is Cat's Claw Used for Today?
-
Dosage
-
Safety Issues
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References
Cat's claw is an herb popular among the indigenous people of Peru, where it is used to treat cancer, diabetes, ulcers, arthritis, and infections, as well as to assist in recovery from childbirth. It is also used as a contraceptive. There are two primary species of cat’s claw used medicinally:
Uncaria tomentosa
and
Uncaria guianensis
.
What Is Cat's Claw Used for Today?
Cat's claw is most often marketed as a treatment for viral diseases, such as
herpes
,
shingles
,
AIDS
, and feline leukemia virus. However, the evidence for these uses is extremely preliminary.
The most meaningful study yet performed on cat's claw suggests that the
Uncaria guianensis
species might be helpful for an entirely different condition:
osteoarthritis
.
3
In addition, one
double-blind
trial indicates that a certain type of
Uncaria tomentosa
may be modestly helpful for people with
rheumatoid arthritis
.
5
Cat's claw has also been proposed as a treatment for
allergies
and
stomach ulcers
, but there is no meaningful evidence as yet that it is effective for these conditions.
What Is the Scientific Evidence for Cat's Claw?
Osteoarthritis
A 4-week, double-blind,
placebo-controlled
trial evaluated the potential benefits of cat’s claw (
Uncaria guianensis
species) for the treatment of
osteoarthritis
.
3
A total of 45 individuals with osteoarthritis were enrolled. Of these, 30 were treated with cat’s claw extract, and 15 were given placebo. Individuals in the treatment group showed reduced pain with activity as compared to those in the placebo group. However, no comparative improvements were seen in knee pain at rest or at night, nor in knee circumference.
This pilot trial suggests that the
Uncaria guianensis
species of cat’s claw may be a useful treatment for osteoarthritis. Another study compared the effectiveness of a proprietary combination of cat’s claw with
glucosamine
sulfate, a widely used dietary supplement for osteoarthritis. Researchers reported the results as positive, but because there was no placebo group the overall effectiveness of this cat’s claw combination product cannot be determined.
6
More research will be necessary to verify this potential use of the herb.
Rheumatoid Arthritis
In a double-blind, placebo-controlled trial of 40 individuals undergoing conventional treatment for
rheumatoid arthritis
, use of an extract made from
Uncaria tomentosa
modestly improved symptoms in individuals with rheumatoid arthritis, as compared to placebo.
5
The researchers conducting this trial made use of recent information indicating that there are two different subtypes of
Uncaria tomentosa
, identifiable based on the chemicals found in them. For this trial, they used the form containing pentacyclic oxindole alkaloids, as opposed to tetracyclic oxindole alkaloids.
Dosage
Numerous widely varying forms of cat’s claw are available commercially. The optimum dosage of each type is not known. In addition, the precise differences in action between the two species of cat’s claw,
Uncaria tomentosa
and
Uncaria guianensis
, as well as the pentacyclic and tetracyclic forms of
Uncaria tomentosa
(see above) are not known.
Safety Issues
In general, use of cat’s claw has not been associated with adverse effects more serious than occasional digestive upset or allergic reactions. However, full safety studies have not been completed, and there has been one report of kidney failure apparently triggered by cat's claw.
4
Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established.
Some evidence suggests that cat's claw might interact with various medications by affecting their metabolism in the liver, but the extent of this effect has not been fully determined.
2
References
1
Jones K. Cat's claw.
Herbs for Health
. 1996;Sept-Oct:42-46.
2
Budzinski JW, Foster BC, Vandenhoek S, et al. An
in vitro
evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures.
Phytomedicine.
2000;7:273-282.
3
Piscoya J, Rodriguez Z, Bustamante SA, et al. Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species
Uncaria guianensis
.
Inflamm Res.
2001;50:442-448.
4
Hilepo JN, Bellucci AG, Mossey RT. Acute renal failure caused by 'cat's claw' herbal remedy in a patient with systemic lupus erythematosus.
Nephron.
1997;77:361.
5
Mur E, Hartig F, Eibl G, et al. Randomized double blind trial of an extract from the pentacyclic alkaloid-chemotype of uncaria tomentosa for the treatment of rheumatoid arthritis.
J Rheumatol
. 2002;29:678-681.
6
Mehta K, Gala J, Bhasale S, et al. Comparison of glucosamine sulfate and a polyherbal supplement for the relief of osteoarthritis of the knee: a randomized controlled trial [ISRCTN25438351].
BMC Complement Altern Med.
2007 Oct 31. [Epub ahead of print]