It's use in Japan is so pervasive that it's sometimes necessary to test Japanese food imports for the presence of Stevia. In the US, if Stevia is being sold as a dietary supplement, an ingredient in a dietary supplement or for research purposes then it's legal as long as no mention of its sweetening properties is made. The hair splitting gets even stranger in this quote:The product is used in these countries as a table-top sweetener in virtually all food commodities and as a flavor enhancer in such products as teas. Stevioside is reportedly 250-300 times sweeter than sugar and contributes no calories to the diet.
This means if the labeling mentions Stevia as a sweetener, even in a "dietary supplement" it's suddenly something that has to be seized. An FDA article on Sugar Substitutes makes brief mention of Stevia. In it Martha Peiperl, a consumer safety officer in the FDA's Office of Premarket Approval is quoted as saying "The safety of stevia has been questioned by published studies." Both FDA articles state that the FDA has not received what they consider sufficient proof that Stevia is safe. Some say Stevia shouldn't even be under scrutiny because it's not a "new" compound, which has fueled conspiracy theories about why the FDA is interested in Stevia.If stevia is to be used in a dietary supplement for a technical effect, such as use as a sweetener or flavoring agent, and is labeled as such, it is considered an unsafe food additive. However, in the absence of labeling specifying that stevia is being or will be used for a technical effect, use of stevia as a dietary ingredient in a dietary supplement is not subject to the food additive provisions of the FD&C Act.
I decided to set aside the fact that at least one Stevia manufacturer has some tinfoil hat level paranoia about Aspartame and focus on finding the studies showing Stevia can be dangerous. Cheerleading articles were easy to find. For example, I found one touting the blood sugar regulating benefits of Stevia. Simple logic would suggest that reducing sugar would have the bulk of the described benefits. I also found a site that pointed out the "200 to 300 times sweeter than sugar" claim is based on the liquid extract. The powdered form is only 10 to 15 times sweeter than sugar. This clarification was consistent with my own experience. I also found a site claiming the FDA ordered the destruction of Stevia cook books. According to the site the FDA later claimed that the publisher decided to destroy them on his own.
DiabetesMonitor.com has a page of quotes. From it I learned the World Health Organization (WHO) is also asking for more research to be done. The WHO and FDA are claiming more studies are needed before declaring Stevia "safe." A company claiming 65% of the world wide Stevia market has a chart listing Stevia's legal status in various countries. I found a lot of churn. Setting aside the alleged anti-Stevia lobbying by NutraSweet, the pro-Stevia arguments boiled down to a lack of evidence that it does harm, its long history of use and its popularity in many Asian countries. The anti-Stevia arguments seemed to boil down to a lack of evidence that it's safe. Hard Evidence took a little more digging.
Stevia.net lists a number of studies and their results, but given the URL, I was not surprised by the overwhelmingly positive nature of the listed results. Finally, I found the WHO Stevia report, a summary of the research the World Health Organization used to evaluate Stevia. At first I wondered why so many of the studies referenced were about the impact of Stevia on reproduction.
An Ebsco Health article on Stevia revealed that Stevia was traditionally used as a form of birth control. It also mentioned that "very high dosages of a stevia extract led to reductions in blood pressure". The problem is, they don't know how MUCH stevia you need to eat or how far it will cause your blood pressure to drop. According to the WHO conclusions, "Stevioside may also act as a calcium antagonist". The main chemicals studied were stevioside and steviol, compounds know to be produced when Stevia is metabolized. The claim that Stevia does not inhibit fertility are based on the tests done with Stevioside. The problem is, oral administration of S. rebaudiana "was reported to cause a severe, long-lasting reduction in fertility". This means eating the plant itself reduces fertility, but none of the compounds KNOWN to result from ingesting it are responsible. There's something else happening when rats are given Stevia and we don't know what it is. According to the WHO report:
This means that even the "safe" dosage levels identified in the studies can't be correlated with real world products. The WHO report is kind enough to offer recommendations on what to do differently. Among them, "specifications must be developed to ensure that the material tested is representative of the material of commerce." The phrase "material of commerce" is commonly used to describe something similar to what will actually be sold to customers. You wouldn't, for example, declare a refined buffered aspirin derivative "safe" because of tests done with Willow Bark Tea. You want to test the pills that will actually be sold. Stevia's backers are glossing over the reproductive concerns by cherry picking which studies they want to quote. There's evidence that stevioside and steviol are NOT the only active compounds resulting from the ingestion of Stevia. The studies were inconsistently done and gave little information about the actual compounds being tested. Then there's the fact that stevia and it's resulting compounds can repress oxidative phosphorylation which impacts glucose absorption and how we extract energy from food. Is Stevia being held to a higher standard than well funded artificial sweeteners like Aspartame? Perhaps. Is Stevia being held to a standard I, as a consumer, would want want applied to it? Hell Yes.In some studies, the material tested (stevioside or steviol) was poorly specified or of variable quality, and no information was available on other constituents or contaminants.