Stevia: Is it safe?

By Louisa Enright | Dec 22, 2010

Stevia rebaudiana is a member of the sunflower family and is a native of Paraguay where it has been used for centuries. The leaves are about 30 times sweeter than sucrose, and the whole leaves contain many beneficial nutrients. Traditional societies used whole stevia leaves to sweeten teas and herbal medicines. Stevia is virtually calorie free.

Jim Earles, in “Sugar-Free Blues: Everything You Wanted to Know About Artificial Sweeteners” (2004), writes that beginning in the late 1970s and early 1980s, a number of United States companies began to use stevia leaves, including Celestial Seasonings, Lipton Tea Company, Traditional Medicinals, and a host of smaller firms like Sunrider International. As the Food and Drug Administration had not ruled on stevia, those firms used a provision in federal law allowing the food industry to make a “self-determination of Generally Recognized as Safe (GRAS) status for items with a long history of `common use in food’ prior to 1958, providing that it enjoyed widespread use without any apparent adverse health effects.”

In 1985, writes Earles, apparently prompted by protests from the NutraSweet Company, maker of aspartame, the U.S. Department of Agriculture forced Sunrider International to burn its supply of stevia, calling it “adulterated.” And, the FDA refused to test stevia samples from Wisdom Natural Brands. Earles reminds that NutraSweet’s newly acquired patent on aspartame was extremely lucrative and that no patent would be awarded to a naturally occurring substance.

Next, Earles continues, the FDA targeted Celestial Seasons and refused to process that company’s petition to give stevia GRAS status. By 1991, the FDA banned the importation of stevia and began raiding health food stores “suspected of selling stevia products” and ordering “the confiscation of books which refer to stevia’s potential use as a natural sweetener.”

The Traditional Medicinals herbal-tea company, the American Herbal Products Association (AHPA), and the Lipton tea company, Earle writes, all tried, uselessly, to present studies to the FDA. The FDA, “ignored their usual protocol and refused to even file the petitions for approval.” Earles thinks that this action “would have left the FDA in the position of having to publicly defend its actions, something which they were unwilling to do.”

Meanwhile, Earles continues, scientists discovered individual sweet compounds (glycosides) within the stevia plant, to include stevioside, steviobioside, rebaudiosides A, B, C, D, and E, and dulcoside A. These purified substances are between 50 to 450 times sweeter than sucrose. But, these extracted substances are highly processed and no longer contain the many nutrients present in whole stevia leaves.

Earle relates that the Japanese, beginning in the early 1970s, “began to take a distinct stand against artificial sweeteners, especially aspartame, due to their possible health risks.” After extensive testing, the Japanese accepted stevia as a safe food additive. By 2004, stevia had “reportedly captured over 50 percent of the Japanese sweetening market.”

Earle acknowledges that FDA officials occasionally, when pressed, indicated that they were worried about two issues: toxicity and a “possible adverse effect on fertility.” Earle discounts these allegations because he cannot find studies that prove them.

In 1995, Earle relates, after efforts from many parties, the FDA revised its 1991 import alert and allowed stevia to be imported, but limited its use to a dietary supplement, which meant that stevia could not be used as a sweetener. The FDA granted stevia GRAS status in late 2008, which allowed stevia to be used as a sweetener.

Why? My guess is big industry saw stevia’s sweetener potential when their existing non-nutritive chemical brews were increasingly being questioned. Both Cole and Pepsi immediately introduced zero or low-calorie beverages featuring rebiana, a highly purified rebaudioside A. The trade names became Truvia (Coke) and OPureVia (Pepsi). Coke’s stevia products include Sprite Green, and Pepsi introduced a grouping of stevia-flavored waters called SoBe Life.

But, apparently there are reasons to avoid stevia.

The Glycemic Research Institute (GRI) delisted and banned stevia in 2008 because “various scientific commissions have determined that Stevia’s potential for toxicity renders it an inappropriate sweetener in humans.” The GRI cites a 2007 study published in “Food Chemistry Toxicology Journal” showing that stevia glycosides exhibit genotoxicity, which means the substance can affect a cell’s genetic structure, causing the genetic material to mutate, or, be mutagenic. The GRI also cites a National Academy of Sciences concurring determination.

The GRI notes that in 1989 and 1999 the European Commission’s Scientific Committee on Foods found “stevioside extracts from Stevia rebaudiana leaves “ to be considered “as toxicologically not acceptable” because existing tests have not followed “Good Laboratory Practice,” because tests for fertility and teratogenicity (fetal malformation) have not been done, and because of questions about the metabolism of stevioside and the mutagenicity of metabolites.

Finally, the GRI determined that “beverages that contain stevia and/or steviol glycosides do not qualify for the `Certified Natural Beverage’ mark.

The GRI report on stevia includes information from the Center for Science in the Public Interest (CPSI) and from a report by toxicologists at the University of California, Los Angeles (UCLA), showing stevia sweetener causes “mutagens and DNA damage, which raises the prospect that it causes cancer.” Both CPSI and the UCLA experts wrote the FDA asking the agency to call for more independently conducted tests and noting that “the FDA’s guidelines advise testing prospective major new food additives on two rodent species, usually rats and mice.” Rats have been tested, but not mice. A lifetime study on mice would more fully evaluate risks. Current tests have been performed by Cargill, which owns Coke.

CPSI’s statement on stevia safety notes that current tests on rats demonstrated the reduction of sperm production and an increase of cell proliferation in the testicles. Tests on pregnant hamsters demonstrated fewer and smaller offspring.

The Mayo Clinic web site notes that stevia’s side effects are “generally mild”: nausea and a feeling of fullness. Mayo cautions that stevia is likely safe in moderate doses, but acknowledges that more research is needed and that until “we have more research, women who are pregnant or breast-feeding should probably avoid using stevia.” Mayo further cautions that “people taking diabetes or blood pressure drugs should use stevia with caution because of the risk that it might cause hypoglycemia or hypotension when combined with these drugs.”

So, is Stevia safe? We don’t know.

I, personally don’t like the taste of stevia, which is a problem many people have. If I did like it, I’d grow the plants, which now are in most nurseries in the spring, and harvest and dry the leaves to enrich tea with nutrients. Thus, I’d be using a whole food, which is how the plant is used traditionally. I much prefer a local, non-heated honey as a sweetener.

Beware the small sweetening packets of stevia. That white powder is highly processed and adulterated with additives like maltodexterin, which is a highly processed carbohydrate, usually from corn, that raises insulin levels. Often, maltodexterin is the first ingredient, which means you’re likely only getting a whiff of stevia. Or, as with Stevita, xylitol is added as a “flowing agent.” Yet, xylitol is a wood alcohol sugar, so I’m suspicious as to its inclusion. Perhaps it’s there to improve the taste?

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