Related Terms

• Beta-amyrin, catechin, desmanthin-1, gallic acid, ginkgoic acid, guaijaverin, mearnsitrin, Myrcia multiflora, Myrcia salicifolia, Myrcia sphaerocarpa, Myrcia uniflora, myricitrin myrciacitrin I, myrciacitrin II, myrciacitrins III, myrciacitrin VI, myrciacitrin V, myrciaphenone A, myrciaphenone B, Myrtaceae, pedra hume caá, pedra-ume-caá, quercitrin, rodwood.

• Note: Do not confuse Myrcia (Myrtaceae family) with the bayberry genus Myrica (or Morella in the Myricaceae family).

Background

• Pedra hume caá is a medium-sized shrub that grows in drier regions of the Amazon and other parts of Brazil. In Brazil, the common name pedra hume caá refers to three species of myrcia plants that are used interchangeably-Myrcia salicifolia, Myrcia uniflorus, and Myrcia sphaerocarpa. It is unknown if reports on pedra hume caá can be applied to other species in the myrcia genus.

• Pedra hume caá has been used by indigenous tribes in the rainforest for diabetes, diarrhea, and dysentery. The Taiwanos tribe (in northwest Amazonia) considers the leaves to be an astringent and uses them for persistent diarrhea. Pedra hume caá has had a place in Brazilian traditional medicine for many years.

• It remains a very popular natural remedy for diabetes throughout South America; the traditional use is a simple leaf tea with a pleasant, slightly sweet taste. It is also used for high blood pressure, enteritis (inflammation of the bowels), hemorrhage, and mouth ulcers.

Scientific Evidence

Tradition/Theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

• Antioxidant, astringent, cardiotonic, diarrhea, diabetic peripheral neuropathy (prevention), diabetic retinopathy, dysentery (severe diarrhea), enteritis (inflammation of the bowels), goiter (enlarged thyroid), hemorrhage, high blood pressure, hyperthyroidism (overactive thyroid), tonic (gastrointestinal), ulcers (mouth).

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

• Based on the available scientific evidence, there is no proven safe or effective dose for myrcia. Traditionally, one cup of leaf infusion has been taken 2-3 times daily with meals or 1-2 grams of leaf powder in tablets or capsules has been taken with meals. Infusion of 3 grams of leaves per day for 56 days has been used in one human trial with no clinical benefit.

Children (younger than 18 years)

• Based on the available scientific evidence, there is no proven safe or effective dose for myrcia in children and use is not recommended.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

• Avoid in individuals with a known allergy or hypersensitivity to myrcia.

Side Effects and Warnings

• There are no reports currently available describing the adverse effects of myrcia. Dizziness, drowsiness, flatulence (gas), abdominal discomfort, bloating, diarrhea, and nausea are possible adverse effects.

• Myrcia has been used historically for high blood pressure. Theoretically, it may cause hypotension (low blood pressure) in some patients. Use myrcia cautiously in patients taking blood pressure medications and in patients with low blood pressure.

• Myrcia may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a qualified healthcare professional including a pharmacist, and medication adjustments may be necessary.

• Patients may experience hypothyroidism with myrcia. Use myrcia cautiously in patients taking medications for hyperthyroidism. Based on its similar activity to some anti-thyroid medications, myrcia may cause agranulocytosis (an acute blood disorder), chills, fever, and loss of taste.

Pregnancy and Breastfeeding

• Myrcia is not recommended in pregnant and breastfeeding women. Myrcia may affect blood sugar levels and thyroid function. Uncontrolled diabetes or thyroid dysfunction during pregnancy can lead to abnormal fetal development.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

• Myrcia may interact with amiodarone causing either an increase or decrease in hypothyroid effects. Caution is advised.

• Myrcia may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

• Myrcia may alter the activity of other blood pressure lowering agents. Caution is advised.

• Myrcia may increase the effects of medications used for hyperthyroidism leading to hypothyroidism. Because of potential effects on thyroid hormones, patients who begin taking myrcia may require dosage adjustments on their existing medications due to changes in metabolism.

Interactions with Herbs and Dietary Supplements

• Myrcia may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

• Myrcia may alter the activity of other blood pressure lowering agents. Caution is advised.

• Myrcia may increase the effects of herbs and supplements used for hyperthyroidism leading to hypothyroidism. Consult with a qualified healthcare professional, including a pharmacist, before combining therapies.

Author Information

• This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

1. Ferreira AC, Neto JC, da Silva AC, et al. Inhibition of Thyroid Peroxidase by Myrcia uniflora Flavonoids. Chem Res Toxicol. 2006;19(3):351-355. View Abstract

2. Matsuda H, Nishida N, Yoshikawa M. Antidiabetic principles of natural medicines. V. Aldose reductase inhibitors from Myrcia multiflora DC. (2): Structures of myrciacitrins III, IV, and V. Chem Pharm Bull.(Tokyo) 2002;50(3):429-431. View Abstract

3. Pepato MT, Oliveira JR, Kettelhut IC, et al. Assessment of the antidiabetic activity of Myrcia uniflora extracts in streptozotocin diabetic rats. Diabetes Res 1993;22(2):49-57. View Abstract

4. Russo EM, Reichelt AA, De Sa JR, et al. Clinical trial of Myrcia uniflora and Bauhinia forficata leaf extracts in normal and diabetic patients. Braz.J Med Biol Res 1990;23(1):11-20. View Abstract

5. Yoshikawa M, Shimada H, Nishida N, et al. Antidiabetic principles of natural medicines. II. Aldose reductase and alpha-glucosidase inhibitors from Brazilian natural medicine, the leaves of Myrcia multiflora DC. (Myrtaceae): structures of myrciacitrins I and II and myrciaphenones A and B. Chem Pharm Bull.(Tokyo) 1998;46(1):113-119. View Abstract