Reproductive effects of Stevia : Rumors and facts

There is been a big concern about Stevia safety, since 2008 when it became to be more and more popular to see Stevia on the shelves. Some websites have posted some studies regarding the fertility possible damage of Stevia and rumors circulating the web that women in South America had been showing fertility issues. The concern come mainly from a very old study dating back to 1968 carried out by Professon Joseph Kuc, where he evaluated the contraceptive properties of this ancient plant.

Kuc’s article conclusion : “ A water extract of Stevia leaves reduces the fertility in female rats, even after 50-60 days of the treatment with the dark solution intake, but it did not affect the health and appetite of the adults subjects”

Professor Kuc states in the article that these results cannot be extrapolated directly to humans and it must to be made again in order to get valid conclusions, some of the reasons are that we used a leaf material that is not present as long with the boiled water based extract. Second he allowed the rats to drink the extract at highly doses that is equivalent to drink 2.5 Liter of liquid in less than half an hour. Third he did set just one dosage and not many to establish what it known as dose response relationship.

Let’s find out other articles that support or debate this idea, maybe you are still intimidated about this article and many post on the web. Is Stevia safe during pregnancy time, breastfeeding or people trying to have a baby?

One study in one of the most respected science data base did a different approach. (Effect of Stevioside on growth and reproduction. Yodyingyuad V, Bunyawong S), this Study was performed at Chulalongkorn University in Bangkog exposing hamsters to daily doses of Stevia extracts on a lapse of time of two generations.

They make four groups of ten male and ten female of one month old hamsters and gave them to the first a daily dose of 500 mg/Kg of Stevioside, 1000 mg/kg to the second group and 2.500 mg/kg to the third one, a control group was set as reference with 9 servings.

Note that in this study Stevioside was used instead of Stevia leaves extract, it changes a lot of the results and of course the conclusions we can obtain. Also it must to be mentioned the human daily intake of Stevioside is estimated to be about 2-5 mg/kg, much lower than the doses were used in this experiment.

The conclusion states there was no significant difference between the average growths of either of the groups, and there was no difference at all between reproductive wellness and reproductive no matter the dose of stevioside the groups consumed. Mating was effective at any dose level.

Another study with similar findings (Southeast Asian J Trop Med Public Health. 2000;31 Suppl 1:171-3. Dominant lethal test in rats treated with some plant extracts.Aritajat S¹, Kaweewat K, Manosroi J, Manosroi A.)

Another study achieved similar findings where stevia extract didn’t affect male body weight, testicular weights and sperm count, morphology and motility. The researchers concluded that it has no toxic effect on male reproduction, at least in rats.

FDA position states that they have approved as safe the purified or refined compounds of stevia leaves, not the whole or crude stevia liquids or extracts, which it does not establish a problem since in the US all the companies use stevioside or rebaudioside either a blend of them at high purities.

So what’s the verdict based on the evidences?

Well there is not apparent evidence to doubt about Stevia safety, scientific findings have demonstrated it and long term use of this plant in Paraguay for ages have no reason to make Stevia an unsafe sweetener, what is approved in the market as sweetener contain purified Stevia extracts. Long term studies for the other leaves components must be finished,  but based on the long dated evidence in Paraguay and Brazil most likely the results would show a final positive response for what people is looking for.

Now we will see that even most of the Stevias are made with purified extracts, the obtaining process and ingredients blended in the formulations can damage the final result of a natural zero calories ingredients, so not all the Stevia are the same, and it depends about the manufacturing process to make a decision about buying one or other Stevia brand.