Does Stevia Cause Infertility?

There has been a lot of debate in recent months as to whether or not Stevia can cause infertility. While Stevia is being touted as the “new” sugar substitute of choice, it is interesting to note that this all natural sweetener has been used for more than 1,500 years with little (if any) side effects.

So, why all the hype regarding Stevia’s ability to alter a woman’s fertility? The answer to that questions stems from two sources: someone mentioning that women in Paraguay use extracts from the Stevia plant as a contraceptive.  And a 32 year old study which cited that Stevia offers a contraceptive effect.

That begs to question, if Stevia can indeed prohibit a pregnancy, why hasn't more research been done to see if it can be used to develop better and safer contraceptives for women? The answer of that that questions is “It has!”
Since the first study performed in Uruguay was released in the 1960’s, there have been countless other studies completed which contradicts its findings. But, first let’s talk about the two main studies used by the FDA to keep Stevia from becoming a common sweetener in American homes.

The Kruc Study

In 1968, Professor Joseph Kruc, a member of Purdue University’s department of biochemistry conducted a study of Stevia at the University of the Republic in Montevideo. Giving a small number of rats very high doses of stevia, it was concluded that the rats given the herbal extract produced less offspring than those who were not.  The problem, even Kruc admits today, is that the rats in the study were given such high doses of Stevia for such a short period of time, that even if it did cause the fertility problems noted, it could have been because of an overdose of the compound. People ingesting Stevia as a sweetener would never be able to consume such a large amount in such a short period of time.

Another concern Kruc admits is that there is no evidence to show that the reaction experienced by the rats would also be experienced by humans.

The Alvarez Study

In 1988, professor Mauro Alvarez of Brazil’s University of Maringa Foundation, repeated the study, reporting in a Brazilian pharmaceutical journal that female mice given Stevia experienced a contraceptive effect similar to those reported by Kruc.

The problem with the results, argue critics is that the Alvarez study lacks the information and analysis required by such a research study and can not be considered valid. According to the Herb Research Foundation the study lacks any credibility at all and should be disregarded.
Even Alvarex himself now claims that further research has led him to believe that Stevia is completely safe for human consumption.  Despite the problems with both studies, the FDA continues to use them as their main source against Stevia.

More Recent Research

Trying to prove that Stevia is indeed a valid natural sweetener which offers no detrimental health or fertility effects to its users, dozens of other researchers throughout the United States and Europe have studied the herbal extract, but to date have found no evidence that it causes any of the problems cited in the earlier reports.

In 1999, the primate research center of Chulalonhkorn University in Bangkok, Thailand gave high doses of Stevia to both male and female hamsters to see if their fertility would be affected. Even though 2,500 mg a day was administered (a human dose is about 2 mg), there was no evidence of decreased fertility.

Then in 2008, researchers reported in the Journal of Endocrinology and Reproduction (vol 12, 2008) that stevia rebaudiana had absolutely no adverse effects of the fertility of female mice.
The same conclusion has been reached in a number of other studies including those conducted by The Herb Research Foundation, Medicinal Plant Research of the USDA and The Division of Pathology, National institutes of Health, Japan.

So, what’s the bottom line?

It seems that while two research studies dating back almost 40 years has kept the FDA from approving Stevia as a common sweetener due to concerns about its effects on both male and female fertility. Yet, dozens of further research studies show no evidence for concern.
Plus, there is some question as to why pharmaceutical companies worldwide have not used Stevia, a completely safe herbal extract, to develop better and more effective contraceptives if indeed it holds these properties. The answer may lie in the fact that it simply doesn’t.

Conclusion

Our conclusion? At this point, there is no evidence to support the claim that Stevia can – or does – cause a decrease in fertility for either men or women. Stevia may be a very useful herb for women who have PCOS and are seeking an alternative to using sugar in their diets. In short it seems that most modern day research shows no evidence that Stevia will decrease your fertility or that it can be used for contraceptive purposes. While this all-natural sweetener seems to appear safe for human consumption, it is important to note that if you personally are worried that it could have an impact to your fertility it is best to avoid it. After all, the stress of wondering whether or not it is keeping you from getting pregnant could in itself impede conception.

Update

In 2010, two review studies found no health concerns with stevia or its sweetening extracts.[1][2] In addition, a 2009 review study found that stevioside and related compounds have anti-hyperglycemic, anti-hypertensive, anti-inflammatory, anti-tumor, anti-diarrheal, diuretic, and immunomodulatory actions.[3]

In 2012, the FDA posted a note on their website regarding crude Stevia plant: "FDA has not permitted the use of whole-leaf Stevia or crude Stevia extracts because these substances have not been approved for use as a food additive. FDA does not consider their use in food to be GRAS in light of reports in the literature that raise concerns about the use of these substances. Among these concerns are control of blood sugar and effects on the reproductive, cardiovascular, and renal systems."(4)

Resources1. Science, (vol 162, Nov. 1968)2. Journal of Endocornoliogy and Reproduction (Vol. 12, 2008)3. The Stevia Cookbook, 199 by Ray Sahelian MD and Suan GatesSources:http://natural-fertility-info.com/does-stevia-cause-infertility.html(1) http://informahealthcare.com/doi/abs/10.3109/09637480903193049(2) http://www.ncbi.nlm.nih.gov/pubmed/20370653(3) http://www.sciencedirect.com/science/article/pii/S0163725808001927(4) http://www.fda.gov/AboutFDA/Transparency/Basics/ucm214864.htm