Stevia is an herb that is used as a sweetener. The FDA allows only a purified ingredient from stevia as a food additive. Some studies have shown that stevia helps lower blood pressure in humans. Other animal and laboratory studies suggest stevia products can suppress inflammation mediators in the body and can help to regulate blood sugar level. However, these effects have not been studied in humans.
Stevia can be used as a low-calorie sweetener.
Stevia may lower blood pressure.
Laboratory studies show that Stevia has antitumor properties but this has not been confirmed in humans.
Laboratory studies suggest that Stevia may reduce inflammation.
Animals studies suggest stevia products can help to regular blood sugar but human data are lacking.
There are no data to support this use.
Some studies show that steviol at high dosages may have weak mutagenic activity.
Do Not Take If
You are pregnant or nursing.
Stevia rebaudiana is an herb native to Brazil and Paraguay. Its raw leaves as well as purified extracts, such as stevioside and its aglycone steviol, have been used as sweeteners and promoted as sugar substitutes for diabetics (2). Stevia extract is said to be many times sweeter than table sugar (1). However, only the purified steviol glycosides have the Generally Recognized as Safe (GRAS) status by the FDA for use in food (8).
In vitro and animal studies indicate that stevia has antitumor (5), anti-inflammatory (6), and hepato- and reno-protective effects (11). Stevia was also shown effective in lowering hypertension and hyperglycemia (3)(13). In a placebo-controlled trial in patients with hypertension, stevioside usage improved quality of life when compared with placebo (4). Well-designed trials are warranted.
Stevia may have additive effects with other antihypertensive and antidiabetic medications. Gastrointestinal and neurological side-effects as well as mutagenic activity have been reported (3)(4)(7).
Mechanism of Action
The mechanisms underlying the antihypertensive effect of stevioside are still unclear, although it is believed to act as a calcium channel antagonist, similar to the drug verapamil (9). It may also have antitumor properties, as evidenced by its inhibition of the tumor-promoting 12-O-tetradecanoylphorbol-13-acetate (TPA) in mouse skin (5). In vitro studies have shown that stevioside suppresses the production of inflammatory mediators (6). Stevia products have been shown to inhibit hepatic gluconeogenesis (10) and increase insulin sensitivity in animal studies (11).
At high doses, steviol was shown to exhibit weak mutagenic activity (7).
Pregnant women should not consume this herb.
Case Report: Four patients in a study experienced abdominal fullness, myalgia, nausea, and asthenia following consumption of 500 mg stevioside powder. Their symptoms disappeared after 1 week of treatment (4).
Verapamil: Stevia may have additive antihypertensive effects (9).
Antidiabetics: Stevia may affect blood glucose level, so dosages may have to be adjusted (10).
More about stevia, a non-approved sweetener. Harv Womens Health Watch 2005;12(10):6-7.