I have never heard of any of this. Stevia is a non-caloric natural sweetener product derived in part from Stevia Rebaudiana , a South American shrub that has been used there for centuries to sweeten beverages. The main ingredient that makes the product stevia taste so sweet is a glycoside that's extracted from this plant called stevioside, which is about 300 times sweeter than table sugar. However, the FDA has expressed some concerns about its safety and has therefore not approved it for use as a food additive to sweeten foods.
Some studies find it harmless while others have noted problems.
The most significant issue is that a large intake of stevia may cause infertility. Other concerns include its cancer-causing potential and interference with the processing of carbohydrates. And if approved, there would be no way to limit the intake for each person. If stevia were permitted in foods and beverages, takers may over-indulge. Japan has been using stevia in various processed foods since the 1970s, and other regions of the world have added it to foods for some time as well.