Healing Properties of Stevia

TRIBAL AND HERBAL MEDICINE USES

For hundreds of years, indigenous peoples in Brazil and Paraguay have used the leaves of stevia as a sweetener. The Guarani Indians of Paraguay call it kaa jheé and have used it to sweeten their yerba mate tea for centuries. They have also used stevia to sweeten other teas and foods and have used it medicinally as a cardiotonic, for obesity, hypertension, and heartburn, and to help lower uric acid levels.

In addition to being a sweetener, stevia is considered (in Brazilian herbal medicine) to be hypoglycemic, hypotensive, diuretic, cardiotonic, and tonic. The leaf is used for diabetes, obesity, cavities, hypertension, fatigue, depression, sweet cravings, and infections. The leaf is employed in traditional medical systems in Paraguay for the same purposes as in Brazil.

Europeans first learned about stevia in the sixteenth century, when conquistadores sent word to Spain that the natives of South America were using the plant to sweeten herbal tea. Since then stevia has been used widely throughout Europe and Asia. In the United States, herbalists use the leaf for diabetes, high blood pressure, infections, and as a sweetening agent. In Japan and Brazil, stevia is approved as a food additive and sugar substitute.

Stevia's effects and uses as a heart tonic to normalize blood pressure levels, to regulate heartbeat, and for other cardiopulmonary indications first were reported in rat studies (in 1978). Following these studies, a crude extract of stevia demonstrated hypotensive activity in a 1996 clinical study with rats, showing that ". . . at dosages higher than used for sweetening purposes, [stevia extract] is a vasodilator agent in normo- and hypertensive animals." In humans, a hot water extract of the leaf has been shown to lower both systolic and diastolic blood pressure. Several earlier studies on both stevia extracts, as well as its isolated glycosides, demonstrated this hypotensive action (as well as a diuretic action). In hypertensive rats the leaf extract increased renal plasma flow, urinary flow, sodium excretion and filtration rate. In addition to its studied hypotensive effects, a Brazilian research group demonstrated that water extracts of stevia leaves had a hypoglycemic effect and increased glucose tolerance in humans, reporting that it "significantly decreased plasma glucose levels during the test and after overnight fasting in all volunteers." In another human study, blood sugar was reduced by 35% 6-8 hours after oral ingestion of a hot water extract of the leaf.

In other research, stevia has demonstrated antimicrobial, antibacterial, antiviral, and antiyeast activity. A water extract was shown to help prevent dental cavities by inhibiting the bacteria Streptococcus mutansthat stimulates plaque formation. Additionally, a U.S. patent was filed in 1993 on a extract of stevia that claimed it to have vasodilatory activity and deemed it effective for various skin diseases (acne, heat rash, pruritis) and diseases caused by blood circulation insufficiency.