Is stevia sweetener truly the "holy grail" of sugar substitutes, as so many of its advocates unceasingly try to convince us?
The popularity of stevia-based sweeteners has risen rapidly in the U.S. in recent years. But if we put all the high-paid hype aside, just what are the facts about stevia-based sweeteners that potential users should know?
Here, we provide a review of current information on the use, safety, and "taste quality" of the most commonly available forms of stevia sweeteners.
What is Stevia?
The plant used as the basis for modern stevia sweeteners is an herb (Stevia rebaudiana) native to South America. The compounds that give the stevia plant its sweetness are concentrated in the leaves.
Generally speaking, all stevia sweeteners may be considered as belonging to one of two broad classes of stevia products:
(1) "Pure" stevia products - those products that either (1) consist solely of whole parts of the stevia plant, OR (2) are not combined with other additives as a final product ( although they may have been subjected to some form of processing to extract and/or concentrate the natural sweetening compounds found in stevia plants)
(2) Stevia-based Products - those products that consist of mixtures of stevia extracts PLUS other additives (including additional sweeteners).
We will consider each of these in turn.
Pure Stevia Products
Stevia leaves have been eaten fresh, or as dried additives to teas and other foods for hundreds of years by certain peoples of South America.
Dried stevia leaves (by definition) have lost most of their moisture content; therefore this form is much sweeter than fresh leaves and are usually the preferred form of whole stevia in general use today.
The actual chemical compounds that impart sweetness to stevia leaves are two glycosides: stevioside and rebaudioside first isolated from the plant by chemists in 1931.
Japan first began cultivating stevia for use as a sweetener during the early 1970s, and even today the main form of stevia sweetener used in Japan remains that of a powdered extract of stevia leaves.
This is manufactured by isolating the sweet glycosides through water or alcohol extraction, and then dehydrating the resulting mixture into a fine powder through vacuum evaporation of the solvent. Ounce for ounce, these substances are some 200-300 times the sweetness of ordinary table sugar. Stevia's sweetening effects have a somewhat slower onset but generally are of longer duration than ordinary sugar.
Pure stevia extracts are water soluble, heat stable, and retain their sweetness through a broad range of acidities, making them highly suitable for sweeteners used in cooking. Stevia glycosides also have negligible glycemic impact (i.e., do not affect short-term blood glucose levels), making them highly suitable brown sugar substitutes for diabetics or others following a low glycemic diet.
When present in high concentrations, many users report that these compounds impart a "licorice-like" aftertaste to foods or beverages to which they are added. Thus, they may work well with some foods but not others.
The quality and purity of various such extracts are highly variable among commercially available products. As one might expect, the purest and sweetest compounds are produced by more time-consuming extraction methods and more rigorous efforts to obtain high quality leaves; thus these superior products are generally also the most expensive.
Are Pure Stevia Sweeteners Safe? According to Zoltan P. Rona, M.D. (Health Naturally, Aug/Sept 1996), stevia extracts have been safely used as natural sweeteners for centuries by peoples of Paraguay and Brazil. These substances have also been used extensively in Japan since the 1970s with no associated increase in cancer or other known health impacts.
Dr. Rona adds that these products are virtually calorie-free, help prevent cavities and do not trigger a rise in blood sugar (i.e., no glycemic impact). He also reports that to his knowledge there has never been a report of an adverse to a natural stevia sweetener.
Nonetheless, widespread use of stevia extracts by US consumers has been delayed for many years because of lack of general approval for such use (as a "sweetener") by the Federal Drug Administration (FDA). Stevia extracts have however been sold as "dietary supplements" in the U.S. for years, because as such they do not require FDA approval.
The FDA's failure to give general approval to pure stevia sweeteners for many years, in spite of voluminous evidence to support the safety of these products, has given rise to more than a few well-researched critiques that question whether the FDA was in this instance trying to protect the American public, or a few favored U.S. food manufacturers.
These suspicions were only heightened when in 2008 the FDA approved several specific stevia-based mixtures to be sold as "sweeteners". All of the approved products were manufactured and promoted by large influential U.S. companies.
Among those products that consist of mixtures of stevia extracts PLUS other additives, the most well-known of FDA-approved stevia sweeteners is marketed under the trade name Truvia; a product developed and tested over a 4-year period by the Coca Cola Co. and its manufacturing partner Cargill.
Truvia is not a "pure" extract of the stevia plant; it consists of a combination of stevia extract AND erythritol (a sugar alcohol). The main manufacturer of Truvia (Cargill) has admitted that 30% of the corn used to produce the erythritol used in Truvia production is genetically modified (GMOs).
Truvia is commercially protected by patents, something not possible with the naturally occurring pure stevia extracts used for centuries in other parts of the world. Since gaining FDA approval and wide exposure to the U.S. public through vigorous marketing, Truvia has gained rapid acceptance as a healthful sugar substitute among low-carb dieters and weight conscious Americans, and now ranks as the 2nd best-selling non-natural sweetener in the U.S.
Truvia is somewhat sweeter than most pure stevia extracts, and lacks some of the "licorice" aftertaste reported by many "pure" stevia users. It is worth noting that Truvia has not been approved by the European Union, Australia, and New Zealand. This may be primarily due to these member nations' tight restrictions on genetically modified foods (GMOs).
MANY people (including yours truly) have reported a variety of unpleasant side effects resulting from Truvia consumption. The reported problems vary considerably from person to person, but the most common complaint (by far) seems to be severe gastro-intestinal discomfort, a common result of consumption of sugar alcohols.
In part, this problem is likely caused by consuming enough Truvia (with its burden of erythritol) to actually achieve the desired sweetening effect. For most consumers, at least 2 packets of Truvia are needed to achieve the same perceived "sweetness" as one packet of Splenda.
Liquid Stevia-Based Concentrates: An increasingly popular form of stevia extract on the market today is that of a liquid concentrate dispensed by a dropper. These products are generally prepared in one of two ways. Dark concentrates are made by simply boiling dried stevia leaves for extended periods thereby extracting the compounds, including the glycosides.
Clear concentrates are generally prepared by dissolving powdered extracts in water alone (or water and alcohol) to make "syrup" of the desired sweetness. Other flavorings - such as vanilla or fruit flavors - are then sometimes added to the clear base concentrate after the fact to provide consumers with more choices and applications of these products.
The Bottom Line on Stevia Sweeteners
"Pure" stevia sweeteners (as defined herein) may be well worth trying if you are looking for a natural healthy sugar substitute. If the taste suits you, you may find your answer to satisfying your sweet tooth.
Consumers need to use their own judgment when considering stevia-based products that contain other additives; you may or may not prefer the taste of such products, and you should at least begin by using them sparingly until it is ascertained that you do not have any negative reactions to such mixtures.
William Alevizon is a semi-retired professor of biological sciences and free-lance writer who specializes in popular articles on a variety of scientific subjects. Our website on the proper use of low glycemic foods in weight loss and health management contains several pages devoted to stevia sweetener and other sugar alternatives.
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