Bearberry: benefits, dosage, contraindications
Scientific name(s)
Arctostaphylos uva-ursi
Family or group:
Plants
Active ingredients:
Arbutin
Indications
Scoring methodology
EFSA approval.
Urinary tract infections ✪✪✪✪✪
A small clinical study conducted in women suffering from recurrent urinary tract infections (cystitis) shows that taking a combined product containing uva-ursi and dandelion three times a day for one month reduces the recurrence rate of urinary tract infections compared with placebo. Women in the uva-ursi group experienced no episodes of cystitis during the following year, versus 23% of the women who took the placebo. The active principle of the uva-ursi leaf comes from the transformation of its main constituent, arbutin, which produces an antibacterial effect in the 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 uva-ursi only for the treatment of urinary tract infections, and not for their prevention. This is partly explained by concern that long-term exposure to hydroquinone may be carcinogenic, based on laboratory research findings. It is recommended not to use it for more than 2 consecutive weeks. The dose of uva-ursi 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 use: 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 ✪✪✪✪✪
Thanks to its anti-inflammatory and diuretic action, bearberry can be taken during an attack, in addition to conventional antispasmodic and analgesic treatment.
Posologie
Oral use: leaf
700 mg
aqueous extract, standardized extract, dry extract
Properties
Antibacterial
Animal research suggests that bearberry may have urinary disinfectant properties that could be beneficial for protection against urinary stone formation, possibly due to the presence of saponins. Arbutin, a major constituent of bearberry, is absorbed by the gastrointestinal tract in unchanged form, but is ultimately eliminated in the urine as hydroquinone conjugates that are hydrolyzed to hydroquinone in alkaline urine. nnAn in vitro microbiological study revealed strong antibacterial properties in 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, whereas urine at pH 6 was ineffective. nnIt has been reported that this free hydroquinone exerts antiseptic and astringent effects. It is active against Candida albicans, Staphylococcus aureus and Escherichia coli. nnIn 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 the urine may be more easily aggregated and excreted.nn
Usages associés
Diuretic
Some animal studies show that bearberry may increase renal water excretion, suggesting diuretic effects. This action is due to the flavonoids, arbutoside and phenolic glucosides contained in bearberry leaves.nn
Usages associés
Dermatologic 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 inhibition of melanosomal tyrosinase activity, rather than suppression of tyrosinase expression and synthesis in human melanocytes.
Anti-inflammatory
Some animal research shows 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
Safe dosage
Adults aged 18 years and over: 700 mg - 1750 mg
- Herbal tea: 1.5 to 4 g of the comminuted herbal 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 a day. 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. Warning, in case of long-term oral use or at high doses. The safety of long-term or high-dose use raises concerns because of the hydroquinone content of bearberry. Hydroquinone is thought to have mutagenic and carcinogenic effects. At high doses (approximately 20 grams of dried herb), it may cause convulsions, 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 the cytochromes CYP3A4 and CYP2C19. The alcoholic extract inhibits CYP3A4 and interferes with P-glycoprotein activity in vitro, causing inhibition 1 hour after exposure. Drugs that may be affected include certain antidepressants, antiepileptics, and anti-ulcer medications, among others. It is important for anyone taking drugs metabolized by these enzymes or transported by P-glycoprotein to consult a healthcare professional before taking bearberry extracts.
Cytochrome P450 3A4: moderate interaction
Aqueous as well as alcoholic extracts inhibit the cytochromes CYP3A4 and CYP2C19. The alcoholic extract inhibits CYP3A4 and interferes with P-glycoprotein activity in vitro, inhibiting it 1 hour after exposure. Medications metabolized by CYP3A4 include, but are not limited to, certain statins (for cholesterol), antihypertensive drugs, some antiretroviral medications, and many other commonly prescribed medicines. 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 use.
In theory, bearberry could worsen retinal thinning with long-term use. It contains hydroquinone, which inhibits melanin synthesis and can lead to retinal thinning.
Contraindications
Pregnancy: prohibited
Bearberry may have oxytocic effects, increasing the speed of labor.
Breastfeeding: prohibited
Bearberry is contraindicated in breastfeeding women.
Children up to 12 years: prohibited
Bearberry is contraindicated in children under 12 years of age.
Urinary tract cancer: prohibited
Contraindicated in cases of urinary tract cancer.
