Medicinal Properties of Uva Ursi
Bears snack on its fruits, Native Americans smoke it, women take it for UTIs. Studies question this traditional use of uva ursi but indicate its potential to combat brain and liver damage, high blood pressure, allergies, and more. Read on to learn the surprising health benefits of uva ursi.
What Is Uva Ursi?
Arctostaphylos uva-ursi is a woody shrub from the Heath family of plants (Ericaceae). Common names for this plant are bearberry, crowberry, kinnikinnick, and pinemat manzanita [R].
Both “Arctostaphylos” (Greek) and “uva ursi” (Latin) mean bear’s grape; supposedly, bears love snacking on uva ursi fruits. Native to North American mountains, uva ursi prefers higher northern areas of Europe, America, and Asia [R].
Uva ursi is just one type of bearberry, the other ones being:
- Arctostaphylos adenotricha (found in the Sierra Nevada)
- Arctostaphylos coactilis (located on the costs of California)
- Arctostaphylos cratericola (found in the high mountains of Guatemala)
Experts don’t agree whether these are subspecies of uva ursi or separate ones. The same meaning of “Arctostaphylos” and “uva ursi” adds more confusion to bearberry naming.
Uva ursi grows as a short, dense bush, with evergreen leaves lasting for a couple of years. Leaves are thick, shiny, and oval with rounded tips. In late spring, uva ursi blooms tiny white-to-pink flowers. Fruits are bright red glossy berries that last until early winter.
Traditional and Modern Uses
According to some records, famous Welsh Physicians of Myddfai used uva ursi back in the 13th century. French botanist Carolus Clusius first described it in 1601, and its medicinal use spread to the rest of Europe by the 18th century.
Folks around the globe have been using uva ursi to treat UTIs, inflammation and stones in the bladder and kidneys, diabetes, and venereal diseases.
Native American people add dried uva ursi leaves to tobacco and other herbs to make a smoking mix or “kinnikinnick.” Swedish and Russian folks use it for skin processing.
Uva ursi found its way to many gardens and urban areas. Its dense bushes and evergreen leaves are attractive and easy to cultivate.
Snapshot of Uva Ursi
- Prevents UTIs
- May protect the liver, brain, and lungs
- May relieve allergies
- Fights bacteria and viruses
- May reduce high blood pressure
- Failed to treat UTIs
- Not well studied in humans
- Not suitable for long-term consumption
- Potentially toxic to kidneys
In herbal medicine, only the dried uva ursi leaves have value. Commercial mixtures and loose teas often contain the entire plant, but that indicates poor product quality.
The main active ingredient is arbutin (5 – 12%), a complex sugar-bound molecule. Enzymes in the gut transform arbutin into hydroquinone, responsible for its main medicinal actions. Standardized uva ursi leaf extracts should contain 420 mg or 20% of arbutin [R, R, R+].
Uva ursi leaves are also rich in tannins such as corilagin (10 – 20%), which clean and shrink body tissues (tannins in wine and berries shrink your mouth). The leaves of uva ursi also contain [R+, R, R+, R+]:
- Phenolic acids: gallic, p-coumaric and syringic acid
- Flavonoids: catechin, quercetin
- Enzymes: beta-glucosidase (arbutase)
- Triterpenes: ursolic acid, α-amyrin,
- Minerals: iron, selenium, manganese
- Other: allantoin, resin, wax, fatty acids
Autumn is the best season to harvest the leaves and get the peak arbutin content. Experts recommend using wild (indigenous) plants for the best product quality [R].
Mechanism of Action
- Preventing the growth of bacteria
- Reversing oxidative damage
- Soothing inflammation and allergic reactions
- Fighting cancer cells
- Protecting the nerves and bone marrow
Although the majority of research about uva ursi focuses on those two compounds, corilagin has also shown the above effects. Astringent (shrinking) and antibacterial properties of corilagin contribute to the impact of uva ursi on UTIs and other infections [R+, R, R+].
Health Benefits of Uva Ursi
Each year, approximately 150 million people suffer from urinary tract infections (UTIs). The resistance of bacteria that cause UTIs – such as E. coli and E. faecalis – to common antibiotics poses huge challenges and makes research about herbal alternatives like uva ursi very important [R+].
In a clinical trial on 57 women with frequent UTIs, uva ursi prevented bladder inflammation. After a one-month (540 mg/day of the dry extract), all women were free of symptoms for 1 year and reported no side effects [R+].
Hydroquinone, the primary metabolite of arbutin, is more efficient against bacteria in alkaline urine (pH ~ 8). Baking soda (6 – 8 g) may alkalize urine and boost the antibacterial action of uva ursi [R+, R+, R].
That said, uva ursi failed to cure UTIs in a much larger clinical study (382 women). By the 4th day of infection, patients reported no difference in symptoms and antibiotic use [R].
A review of clinical data and traditional uses also questioned the ability of uva ursi (bearberry) to treat UTIs. The authors suggested it for short-term prevention and emphasized the need for large well-designed trials. A team of German doctors has already announced one [R, R].
Health Benefits With No Clinical Evidence
Uva ursi showed the following health benefits in animal and cell studies only.
2) Other Uterine Tract Issues
In a study on rats, uva ursi extract could dissolve kidney stones and clean the urinary tract. Once again, the authors pointed to the role of alkaline pH in these effects [R].
Enhanced urination (diuretic effect) is one of the body’s mechanisms to get rid of bacteria in the urinary system. Herbs and substances with this action may also help with UTIs and prevent kidney stone build-up [R].
Uva ursi was able to increase urine flow in rats while maintaining the electrolyte balance [R].
3) Liver Protection
Corilagin, which is abundant in uva ursi leaves, may protect the liver against parasitic infections, potentially toxic drugs (Tylenol), bleeding caused by injuries, and impaired bile acid flow. In different studies on rats and mice, corilagin [R, R, R, R, R, R]:
- Repaired oxidative damage
- Normalized liver enzymes
- Reduced inflammation
- Boosted the levels of glutathione
- Prevented cell death and liver scarring
In studies on mice, corilagin cut the growth of liver cancer by up to 47%. It killed cancer cells without damaging the liver. Corilagin also boosted the effects of chemo (cisplatin and doxorubicin) on liver cancer. One cell study found the same [R, R, R, R].
This potent tannin from uva ursi (bearberry) leaves showed similar effects in mice with breast cancer and bile duct cancer. Cell experiments confirmed that corilagin could kill cancer cells and block their spreading [R, R].
Arbutin, the primary active substance in uva ursi leaves, showed a strong action against malignant melanoma (dangerous skin cancer) cells. In different experiments, arbutin blocked the expression of cancer-causing genes and killed melanoma cells [R, R, R].
Arbutin may also protect against the damaging effects of radiation, another common cancer treatment. It prevented deformation and death of bone marrow cells in irradiated mice [R].
One cell experiment confirmed the radioprotective action of arbutin [R].
6) Inflammation and Allergies
- Sooth the animals’ skin
- Decrease inflammation and swelling
- Relieve allergic reactions
- Support standard treatment with NSAIDs and corticosteroids
A cream with uva ursi extract (1 – 2%) showed similar results when applied to animals’ skin. It couldn’t decrease swelling on its own, but it boosted the effects of a corticosteroid cream [R].
7) High Blood Pressure
Many drugs for high blood pressure work by stimulating urination (diuretics). Uva ursi extract showed the same effect in rats, confirming its blood pressure-lowering potential [R].
8) Protection of Blood Vessels
Corilagin may protect blood cholesterol (LDL) from oxidative damage, a major cause of plaque buildup in blood vessels (atherosclerosis). In cell experiments, it was equal or even more potent than EGCG, an antioxidant from green tea [R, R, R+].
Arbutin from uva ursi (bearberry) leaves may also contribute to this health benefit. In a study on rats, it blocked the oxidative damage of blood lipids. However, a doubled dose (100 mg/kg) had the opposite effect [R].
9) Lung Health
Corilagin found in uva ursi leaves was able to protect mice from a lung-harming chemical by [R]:
- Blocking oxidative stress
- Suppressing inflammatory proteins (TNF-alpha, IL-1beta, NF-κB)
- Relieving lung injuries and scarring
In a cell study, corilagin protected lung cells against cigarette smoke in a similar way [R].
Anti-inflammatory and antioxidant actions of corilagin may also benefit the brain. In epileptic rats, corilagin was able to decrease the number of seizures and repair brain damage [R].
Arbutin has similar effects in lab animals – it reduced signs of seizures and prevented memory loss [R].
11) Parkinson’s Disease
Oxidative stress can damage dopamine neurons and may eventually lead to Parkinson’s disease.
In a study on mice, corilagin blocked pain signals 20 times stronger than aspirin [R].
Antibacterial effects of uva ursi (bearberry) aren’t limited to urinary tract infections. In a cell study, uva ursi extract cut the growth of MRSA – a dangerous type of bacteria (S. aureus) resistant to common antibiotics. When combined with antibiotics, uva ursi boosted their potency 100 – 2,000 times [R].
With more research, doctors may use this feature to tackle severe MRSA infections of the skin, lungs, and blood.
Corilagin may prevent the spreading of the HIV-1 virus by blocking its 2 essential enzymes – protease and reverse transcriptase. Corilagin was effective even against the drug-resistant HIV strains, making it a promising herbal add-on. However, clinical studies are needed to determine its effects in people with HIV [R, R].
Skin Benefits of Uva Ursi
In melasma, the buildup of melanin (skin pigment) causes brown-gray skin spots, usually on the face. In clinical trials on 150+ patients, a cream with hydroquinone (2 – 4%) served as a control treatment with proven efficacy [R, R, R, R].
A review of 30 clinical trials proclaimed arbutin an efficient depigmenting (lightening) agent [R].
In our body, arbutin turns into hydroquinone, which has caused some safety concerns. In some animal studies, it increased the risk of kidney cancer. However, this effect was limited to one strain of older male rats and had no human consequences [R, R].
Injecting hydroquinone damaged bone marrow of some lab animals, but oral consumption did not [R].
A review of safety studies confirmed that hydroquinone is safe for humans, even in concentrations 100 times higher than uva ursi treatment could reach [R].
Given the above findings, kidney disease patients may want to avoid uva ursi (bearberry) just in case.
Due to some signs of long-term hydroquinone toxicity, experts recommend limiting uva ursi treatment to 1 week and up to 5 times per year. Children under 12 years should skip uva ursi (according to the European Medicines Agency) [R+, R+].
Safety in Cosmetics
According to the Scientific Committee on Consumer Safety (SCCS), arbutin in cosmetic products is safe in concentrations up to 0.5% (body lotions) and 2% (face creams) [R].
Limitations and Caveats
- Clinical data on the benefits of uva ursi for UTIs is minimal and conflicting
- Uva ursi has shown other medical properties in animal and cell studies only
- Most of these studies used isolated components, not the uva ursi extract
- Statins (high-cholesterol drugs)
- SSRIs (antidepressants)
- Azoles (antifungal drugs)
- Some antibiotics and antiviral drugs
Drugs and herbs that enhance urination (diuretics) – including uva ursi leaves – may provoke the side effects of lithium, used for bipolar disorder. Due to its diuretic action, uva ursi may enhance the effects of drugs for high blood pressure [R, R].
Forms of Supplementation & Dosage
Pills with dry uva ursi (bearberry) leaf extract are the most common form of supplementation. Some products are standardized to 20% of arbutin. Uva ursi is also available as:
- Loose tea (dried leaves)
- Tea bags
- Liquid extract (tincture)
Uva ursi is also popular in cosmetics. Different skin-lightening serums and creams contain uva ursi leaf extract and its main components – arbutin and hydroquinone.
- Infusion (tea): 3 g of dried leaves in 150 ml of water, 3 – 4 times per day for 1 week
- Powdered leaves: up to 1,750 mg/day, divided into 2 – 3 doses
- Liquid extract (tincture): 1.5 – 4 ml/day (max. 8 ml/day)
Combinations With Other Herbs
In a successful clinical trial (UTI prevention), women took a supplement with uva ursi leaf and dandelion root extracts [R+].
People often combine uva ursi with other herbs that stimulate urination, relieve inflammation, and help combat UTIs. Corn silk, nettle and parsley leaves, horsetail, and marshmallow root are frequent in those mixtures.
Cranberry juice (or extract) is a popular natural remedy for UTIs, but you shouldn’t combine it with uva ursi leaves. It makes urine acidic, weakening the antibacterial effects of uva ursi [R+].
Users mostly take pills with uva ursi leaf extract to treat or prevent UTIs. The majority of them reported positive results and no side effects. Some users experienced no benefits, with a few cases of nausea and headache.
People also use lightening serums and creams with uva ursi extract or arbutin to remove dark spots and soften the skin. They have reported mix results.
Buy Uva Ursi
Arctostaphylos uva-ursi is a small woody shrub that prefers high northern areas of Europe, Asia, and America. It’s the most popular type of bearberry, used in traditional medicine to treat urinary tract issues, diabetes, inflammation, and skin spots. Only the leaves have medicinal value.
Uva ursi leaves contain arbutin and corilagin, which have antimicrobial, anti-inflammatory, antioxidant, and immune-supporting effects. Clinical trials haven’t confirmed the ability of uva ursi to treat UTIs, but it may prevent them.
Animal and cell studies indicate the potential of uva ursi to help with kidney stones, allergies, brain damage, cancer, high blood pressure, and more.
Arbutin and its metabolite (hydroquinone) block the production of the skin pigment melanin. Cream with hydroquinone can improve melasma, a condition in which melanin build-up causes dark skin spots.
Pregnant and breastfeeding women, children under 12 years, and kidney patients should avoid uva ursi.
Clinical trials revealed no significant side effects of uva ursi. Due to some safety concerns, experts recommend limiting its use to one week, up to 5 times per year.
The most common form of supplementation is pills with uva ursi leaf extract (2-5 g daily). It is also available as a dried herb (leaves), tea bags, and liquid extract (tincture). Serums and creams for skin lightening often contain uva ursi extract, arbutin, or hydroquinone.