Nonnutritive Sweeteners: Help or Hindrance? (Part 3)

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Thanks to everyone who posted questions last week! The use of sweeteners in people both with and without diabetes is always a great topic for discussion, and I’m glad to see that folks have done their homework and are asking questions about all of the products out there. We continue with the sweetener saga. The sweetener of the week this week is stevia (or rather, rebiana, a stevia-based sweetener).

What is it? Stevia is a shrub (related to chrysanthemums) native to South America. Its leaves have been used for many years by the people of Brazil and Paraguay to sweeten a beverage called yerba mate. The substances in this herb that make it sweet are called steviol glycosides; the sweetest and best tasting of these steviol glycosides is rebaudioside A, or rebiana.

Where is it grown? Stevia is grown in South America, Central America, Israel, Thailand, and China. It’s highly popular in Japan, where it’s used (in place of aspartame and saccharin) to sweeten beverages, candy, and soy sauce.

Is it safe? Stevia has been available in the US for many years as a dietary supplement, not as an “officially approved” sweetener. In the 1990’s, the FDA (along with Canada and a European Community panel) rejected the approval of stevia as a sweetener due to concerns about its safety. For example, high doses of stevia fed to rats led to decreased sperm production. Pregnant hamsters given a form of stevia had smaller offspring. And in the laboratory, stevia was believed to damage DNA, thus possibly increasing the risk of cancer.

Why is stevia approved as a sweetener now? Recently, two companies (Cargill and Whole Earth Sweetener, a division of Merisant) developed an extract of stevia that is 97% pure rebaudioside A and roughly 200 times sweeter than sugar. They submitted research to the FDA attesting to rebiana’s safety, and in December 2008, the FDA agreed that rebiana could be put on the GRAS (Generally Recognized As Safe) list for use as a general purpose sweetener. In order to get on the GRAS list, an ingredient or chemical added to foods and beverages must be deemed by qualified scientists to be safe for consumption, as evidenced through scientific procedures or through experience based on common use in food.

You should note that only the stevia extract rebaudioside A or rebiana has been approved for GRAS status. The use of stevia, a sweetener made from a crude preparation of dried stevia leaves, has not been approved by the FDA. Rebiana is a food-grade, high-purity extract of the stevia leaf that contains at least 97% rebaudioside A.

Is rebiana safe? Like the other nonnutritive sweeteners, rebiana has been studied and found to be safe for people of all ages to consume. Safety data is based on 25 years of research on steviol glycosides. And if you’re curious, rebiana is not absorbed in the small intestine. It’s actually broken down by bacteria in the colon into steviol. Steviol is absorbed, turned into another substance in the liver and then excreted in the urine. Studies published in the May 2008 issue of the journal Food and Chemical Toxicology showed that very high doses of rebiana (the equivalent of a 150-pound person drinking 2,000 8-ounce servings of a rebiana-sweetened drink) had no ill effects on any organs in the body. Data also shows that rebiana has no effect on blood glucose or blood pressure.

However, the consumer watchdog Center for Science in the Public Interest (CSPI) point out that rebiana has only been tested in rats (FDA guidelines advise that testing be done on both rats and mice, and there could be some concern with DNA damage, based on earlier studies with stevia fed to rats). But despite urging from CSPI and several toxicologists from UCLA for the FDA to study rebiana further, rebiana was granted GRAS status in 2008.

What’s the Acceptable Daily Intake (ADI) for rebiana? The ADI for rebiana is 12 milligrams per kilogram of body weight per day for adults and children. This translates into a 150-pound adult consuming about 30 packets of a rebiana sweetener (such as Truvia) or drinking about six 12-ounce cans of a rebiana-sweetened soda every day for life.

More on stevia (rebiana) sweeteners next week!

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