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Is Stevia Safe?
Yes, it’s “natural,” but there are concerns that stevia might cause DNA damage.
Questions raised about stevia safety
photo: Ethel Aardvark

Based on existing research, the Food and Drug Admminstration has neither approved nor blocked the movement of stevia into the food supply. Yet Pepsi and Coca-Cola are going ahead with plans to introduce products containing the natural sweetener into the market. Curtis Eckhert, a professor at UCLA and a co-author of the University’s toxicology report on stevia, explains some of his biggest concerns with existing studies’ findings on the much-hailed sugar-substitute.

What were some red flags that came up during your review of existing literature about stevia?

Most of the research has been done on a molecule called stevioside. But they were asking for [approval of] another chemical with a modified structure called rebaudioside A. That raises a concern right away because the basis of pharmacology is alteration of structure, which changes how a chemical it interacts with the body. Then they said rats were a good model for humans, but when you actually look at the data, rats and human differ on how they pass it through the body. Another issue was the blood concentrations in female rats were almost twice as high as in male rats given the same amount. That means that if this were to also happen in humans, then girls would have double the blood levels of males. This then puts a very susceptible population at risk, particularly in the fast-food industry: girls who might get pregnant.

What about stevia’s effects on DNA?

Some tests look for damaged genes, and some tests look at their ability to totally delete genes. What they found was it could totally delete a gene. What that means is if you looked for damage, you wouldn't see it because the gene's not there to be damaged. … If you just designed a study to look at all this, it could be done, and then you would know if it's safe. But as it is now, these unanswered questions raise our concern.

Stevia has been sold in health stores for years as a supplement. How is this different?

If you sell something as a supplement, it's a small population of people who take it, but if you start putting it in Pepsi and Coke and cake and cupcakes, you hit a much larger food supply and population. Companies know that people who are interested in health will do large population studies. This is going to happen. It has nothing to do with me. When that happens, there's a certain probability that they will find something, and if it's repeatable the companies automatically have a risk of liability. If they've done these studies [themselves], distributors would have a much higher level of protection.

Have the people who took stevia as a supplement suffered health problems?

If you just designed a study to look at all this and then you would know if it's safe. But as it is now, these unanswered questions raise our concern.

You'd have to actually do a study to find out. Remember, tobacco was shown by King George to be harmful to lungs back in the 1600s. So tobacco was known to probably be bad, but they didn't do any studies until the 1950s, when it was shown to cause lung cancer. Until you actually do a study, you don't know. And as far as I can tell, they have certainly not looked at the compound that's going to go into our food. … I don’t understand why members of the board of directors of Pepsi and Coke don’t fund those studies to protect the companies. I don’t understand why their insurance companies aren’t sufficiently concerned about the risk to require the studies.

What would you recommend to quick-serves considering carrying stevia products?

I recommend they check with their insurance company and their lawyers to make sure that any liability falls upon the distributor and not on them.

Robin Hilmantel is a regular contributor to