Bearberry: Benefits, Dosage, Contraindications
Other name(s)
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Scientific name(s)
Arctostaphylos uva-ursi
Family or group:
Plants
Active ingredients:
Arbutin
Indications
Rating methodology
EFSA approval.
Urinary tract infections ✪✪✪✪✪
A small clinical study conducted in women with recurrent urinary infections (cystitis) shows that taking a combined product containing bearberry and dandelion three times a day for a month reduces the recurrence rate of urinary infections compared to a placebo. None of the women in the bearberry group experienced any cystitis episodes over the following year, whereas 23% of the women taking the placebo did. The active principle from bearberry leaves results from the transformation of its main constituent, arbutin, which leads to an antibacterial effect in urine. Arbutin alone would be an effective urinary antibiotic, but only if taken at a high dose and if the urine is alkaline. The German Commission E has approved the use of bearberry only for treating urinary infections, not for prevention. This is partly due to concerns that long-term exposure to hydroquinone may be carcinogenic, according to laboratory research information. It is recommended not to use it for more than 2 consecutive weeks. The dose of bearberry recommended by Commission E is 3 g of leaves extracted in 150 ml of water by hot or cold infusion up to four times a day, providing 400-840 mg of arbutoside.
Posologie
Oral: leaf
700 mg
aqueous extract, standardized extract, dry extract
Synergies
European Union herbal monograph on Arctostaphylos uva-ursi (L.) Spreng., folium
Botanical medicines for the urinary tract
Urinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract as film-coated tablets and aqueous solution in healthy humans
E/S/C/O/P: 2nd Edition of the ESCOP Monographs
Prophylactic effect of UVA-E in women with recurrent cystitis: A preliminary report
Renal colic ✪✪✪✪✪
Due to its anti-inflammatory and diuretic action, bearberry may be taken during the crisis, in addition to classic antispasmodic and analgesic treatment.
Posologie
Oral: leaf
700 mg
aqueous extract, standardized extract, dry extract
Properties
Antibacterial
Animal studies suggest that bearberry may have urinary disinfectant properties beneficial for protection against urinary lithiasis, possibly due to the presence of saponins. Arbutin, a major constituent of bearberry, is absorbed unchanged by the gastrointestinal tract but is eventually excreted in the urine as hydroquinone conjugates, which are hydrolyzed into hydroquinone in alkaline urine. An in vitro microbiological study revealed strong antibacterial properties of urine samples obtained from healthy volunteers after consumption of 800 mg of arbutin or bearberry containing an equivalent amount of arbutin. This effect was observed only with urine adjusted to a pH of 8, while urine with a pH of 6 was ineffective. Free hydroquinone reportedly exerts antiseptic and astringent effects. It is said to be active against Candida albicans, Staphylococcus aureus, and Escherichia coli. In vitro research shows that aqueous extracts of bearberry leaves increase the hydrophobicity of gram-negative bacteria such as E. coli and Acinetobacter baumannii. This suggests that bacterial particles in urine could be more easily aggregated and excreted.
Usages associés
Diuretic
Some animal research shows that bearberry can increase renal elimination of water, suggesting diuretic effects. This action is due to flavonoids, arbutoside, and phenolic glycosides contained in bearberry leaves.
Usages associés
Dermatological Effect
In vitro research suggests that bearberry and its constituents, mainly arbutin, inhibit melanin synthesis. In one study, arbutin was found to reduce melanin formation in melanocytes by inhibiting tyrosinase and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) polymerase. Another study on human cell cultures showed that the depigmenting effect of arbutin is due to the inhibition of melanosomal tyrosinase activity, rather than suppression of tyrosinase expression and synthesis in human melanocytes.
Anti-inflammatory
Some animal studies show that arbutin synergistically enhances the anti-inflammatory properties of prednisolone in mice. Arbutin alone requires a dose of 100 mg/kg or more to produce significant anti-inflammatory effects.
Usages associés
Safety dosage
Adult from 18 years: 700 mg - 1750 mg
- Tea: 1.5 to 4 g of crushed plant substance in 150 ml of boiling water as an infusion or in 150 ml of water as a macerate 2 to 4 times a day. Maximum daily dose: 8 g. - Powder, single dose: 700 mg (2x350 mg) twice daily. Maximum daily dose: 1.75 g (5x350 mg). - Dry extracts: the dose corresponding to 100-210 mg of arbutin 2 to 4 times a day. Daily dose: 400-800 mg. Caution, with long-term or high-dose oral use. Long-term or high-dose use safety concerns exist due to bearberry's hydroquinone content. Hydroquinone is thought to have mutagenic and carcinogenic effects. At high doses (about 20 grams of dried herb), it can cause seizures, cyanosis, delirium, shortness of breath, and collapse. At very high doses (30 grams of dried herb or more), it can be fatal.
Interactions
Médicaments
Cytochrome P450 2C19: moderate interaction
Both aqueous and alcoholic extracts inhibit CYP3A4 and CYP2C19 cytochromes. The alcoholic extract inhibits CYP3A4 and interferes with P-glycoprotein activity in vitro, with inhibition 1 hour after exposure. Medications involved may include certain antidepressants, anti-epileptics, and anti-ulcer medications, among others. It is important for anyone taking medications metabolized by these enzymes or transported by P-glycoprotein to consult a healthcare professional before taking bearberry extracts.
Cytochrome P450 3A4: moderate interaction
Both aqueous and alcoholic extracts inhibit CYP3A4 and CYP2C19 cytochromes. The alcoholic extract inhibits CYP3A4 and interferes with P-glycoprotein activity in vitro, with inhibition 1 hour after exposure. Medications metabolized by CYP3A4 include, but are not limited to, certain statins (for cholesterol), hypertension medications, some anti-HIV drugs, and many other commonly prescribed medications. It is important for anyone taking medications metabolized by these enzymes or transported by P-glycoprotein to consult a healthcare professional before taking bearberry extracts.
Precautions
Retinopathy: avoid
In theory, bearberry may worsen retinal thinning with long-term use. It contains hydroquinone, which inhibits melanin synthesis, potentially leading to retinal thinning.
Contraindications
Pregnant women: prohibited
Bearberry may have oxytocic effects, increasing the speed of labor.
Nursing women: prohibited
Bearberry is contraindicated for nursing women.
Child up to 12 years: prohibited
Bearberry is contraindicated for children under 12 years.
Urinary tract cancer: prohibited
Contraindicated in cases of urinary tract cancer.
