Stevia Article Series

Stevia Side Effects -
The Facts: Part 3

Thursday, 11 January 2013

Steviol glycosides are effective against harmful bacteria?

An interesting study (in vitro), published in 2008, compared the antifungal and antibacterial activity of solvent extracts of stevia on microorganisms, such as E. Coli, compared to ordinary anti-biotics.

In a solvent extract of petroleum ether, stevia leaves showed significant antimicrobial activity against food-spoiling fungi such as A. Niger and P. Chrysogeum, opening up a potential for exploration as a valuable addition to food preservatives such as sugar. It also exhibited antifungal activity higher than standard fungicides used against plant pathogens A. Solani and H. Solani. Its potential as an effective bio-fungicide seems promising. In addition high antimicrobial activity was exhibited against  E. Faecalis and S. Aureus, two well-known animal pathogens.
(Ghosh, Subudhi, Nayak, 2008)

Our conclusion: We agree with the study’s conclusion that steviol glycosides are strong possible future candidates as food preservatives, plant microbiocides or anti-biotic pharmaceuticals. Further studies in plant and animal models as well as clinical trials would be necessary.

Steviol glycosides can reduce blood pressure?

A number of studies, in vitro, suggest steviol glycosides inhibit vasoconstriction. Stevioside administered in vivo, following ingestion, is hydrolysed to steviol before absorption. There is therefore very limited exposure of the smooth muscle cells to stevioside, and its effects on blood pressure, in vitro,, cannot be interpreted in terms of its effects as reported in animal and human studies.
(Lee et al., 2001), (Liu et al., 2003)

A number of studies that record blood pressure effects have been carried out on human subjects. Three of these studies showed no clinically important changes in blood pressure.
(Maki et al., 2008b), (Barriocanal et al., 2008), (Ferri et al., 2006)

Two studies, in China, have indicated that treatment with steviol glycosides in 100 – 200 subjects, over 50 years old, with mild hypertension, showed blood pressure values were statistically significantly decreased, although the purity of the stevioside was not reported.
(Hsieh et al., 2003), (Chan et al., 2000)

Our conclusion: While the results of the studies are not conclusive there remains the possibility that there is some association between the consumption of steviol glycosides and the reduction in SBP and DBP values. Care should be taken when used by those with hypotension (low blood pressure) and medical advice sought as necessary.

Steviol glycosides can increase urine production?

A study on rats has shown that oral-administration of the equivalent of 2.67 g dry stevia leaves/day for 30 days resulted in an increase in urinary flow due to its diuretic properties, an increase in sodium excretion and changes in other renal activities.

Our conclusion: Higher doses of steviol glycosides may increase urinary flow in humans. Persons with impaired kidney function or kidney disease should exercise caution and seek medical advice as necessary.