Stevia, sold as a “dietary supplement,” is no stranger to the
health food world and under this heading one finds extracts
of quite varying composition and purity. More narrowly, stevia
also is used to indicate an extract consisting only of stevioside.
The leaves of stevia rebaudiana Bertoni are the primary source,
but related species are native from Mexico to throughout South
America and known by names such as sweetleaf, sweet leaf and
sugarleaf, as well as stevia. The leaves of the plant are 30–45
times as sweet as table sugar and stevioside is 200–300 times
as sweet as sucrose. In Paraguay the plant has been used for
centuries as a medicinal herb and as a sweetener for mate and
other beverages. Stevia extracts of varying composition have
been used widely as sweeteners in Japan since 1971 without
restriction or reported health hazards. Indeed, there are both
animal and human data that suggest that stevia extracts may
increase insulin sensitivity and improve blood glucose control
without side effects. Most health food shoppers no doubt
assume that stevia is officially accepted as a natural, calorie
free herbal extract that can be used as a sugar substitute or as
an alternative to artificial sweeteners. After all, stevia in all of
its forms can be purchased freely as a dietary supplement.
Those making this assumption would be wrong. To this
day, stevia remains on a total United States FDA Import Alert
as an “unsafe food additive”— the FDA technical category that
includes sugar substitutes. The exception, as of December
2008, is the steviol glycoside called rebaudioside A, which
is allowed to be sold as a “food additive,” that is, as a sugar
substitute or sweetener. Rebaudioside A is available under
trade names including Only Sweet, PureVia, Reb-A, Rebiana,
SweetLeaf and Truvia. The developers of all allowed versions
are Cargill and The Coca-Cola Company (in the case of Truvia),
or PepsiCo and the Whole Earth Sweetener Company, a
subsidiary of Merisant (in the case of PureVia).
In other words, stevia is safe if it is sold as a dietary
supplement, but it is unsafe if sold as a food additive, which
is to say, as a sweetener. The sole exception is rebaudioside
A. How this state of affairs came about requires a bit of
SLOW ACCEPTANCE OF A SUGAR ALTERNATIVE
The potential market for stevia as a sweetener is huge.
Sugar has been the great American “success story.” In 1850,
approximately 55 percent of the calories in the American
diet came from complex carbohydrates. Today, that figure is
only about 20 percent. Authorities estimate that perhaps 15
percent of the calories in the American diet now come from
fructose (mostly derived from corn) and that a total of at least
25 percent of the calories in the standard American diet come
from added sugars. This amounts to more than 150 pounds
of added sugars per person per year. Simple sugars have now
supplanted complex carbohydrates as the dominant source of
carbohydrates in the American diet. The question is whether
natural sweeteners can claim a share of sugar’s “success.”
No one doubts that there are incentives for the adoption
of natural sweeteners. Our sweet tooth has created an
enormous market, but one with an equally great downside.
More than 60 percent of adult Americans are overweight or
obese; moreover, year-by-year the epidemic of weight gain
seems to claim a growing percentage of younger individuals.
Artificial sugar substitutes have capitalized on our love/hate
relationship with all things sweet, yet many consumers feel
at least vaguely uneasy about habitually ingesting saccharin,
aspartame, acesulfame K or sucralose. Despite this unease,
natural sweeteners as of yet have not been able to break out of
comparatively tiny niche markets.
Reasons for the failure of sales of natural sweeteners
to expand fall under several headings. Taste is one of these.
Quite a number of carbohydrate sugar substitutes exist, but,
along with varying amounts of calories, most of these provide
less sweetness and a poorer flavor profile than is found with
sucrose, much to the consumer’s chagrin. An example of this
is tagatose, which is 90 percent as sweet as sucrose and has
1.5 calories per gram. Sugar alcohols would appear to be better
candidates. Indeed, one well-known sugar alcohol, xylitol, is
roughly as sweet as sucrose. It also offers the advantages of
protecting against tooth decay while supplying 2.4 calories per
gram. However, sugar alcohols can have a laxative effect in many
individuals when ingested in significant quantities at one time.
Another prominent concern is that sugar substitutes often are
not useful in cooking because of flavor changes, a failure to lead
to desired developments in texture and color when baked, and
so forth. Stevia’s flavor profile typically exhibits a slower onset
and longer duration than that of sugar; some extracts at high
concentrations, however, can leave a bitter aftertaste.
Another hurdle is regulatory definitions, as in the
case of stevia. In order to be labeled a “natural” sugar
substitute as opposed to being a synthetic “food additive,”
such as aspartame, a natural compound should also be a
carbohydrate. Steviol glycosides in chemical terms have a
glucose component, but this “sugar” is not readily cleaved
and thus it is questionable whether stevia can be characterized
as a carbohydrate any more than the flavonoid rutin can be
characterized as a carbohydrate even though it is a flavonoid
glycoside. Therefore according to some regulatory thinking,
stevia must be labeled a “dietary supplement” and not a
sweetener or sugar substitute.
In retrospect, the definitional hurdle for stevia seems to
have played no role in the troubles the compound has faced
in achieving acceptance by the FDA as a sugar substitute.
Instead, a concern over safety was raised. The manner in
which this came about and the attendant controversy could be
expanded to fill many pages.
IS STEVIA SAFE?
Stevia leaves have been used for hundreds of years in Paraguay
and Brazil to sweeten local teas and medicines and as a “sweet
treat.” In the modern period, the Japanese have been using
stevia as an at-home sugar substitute, in food products and in
soft drinks (including Coca Cola) since 1971. Stevia accounts
for 40 percent of the Japanese sweetener market. Stevia is
widely used in East Asian countries and in many other states
around the world. At the very least, it has been consumed
safely by millions in Japan for approaching four decades
without reports of toxicity.
Given its record of a long history of use, both traditionally
and in modern industrial countries, the issue of stevia’s safety
seems a bit of a stretch. Indeed, the circumstances surrounding
the FDA’s declaring stevia an “unsafe food additive” and
restricting its import led one Congressman to label the FDA’s
action against stevia “a restraint of trade to benefit the artificial
sweetener industry.” The FDA total Import Alert and restriction
on stevia as a sweetener resulted from an anonymous 1991
“industry” complaint. Giving verisimilitude to the charge of
collusion with industry is the fact the FDA deleted names
in the original complaint in its responses to requests filed
under the Freedom of Information Act. The FDA’s stated
reason for forbidding importation in the Import Alert was and
remains “toxicological information on stevia is inadequate to
demonstrate its safety.” As many reviews have pointed out, the
1994 Dietary Supplement Health and Education Act forced the
FDA to permit stevia’s use as a dietary supplement, although
not as a food additive, a position that simultaneously labels
stevia as both safe and unsafe depending on how it is sold.
Tellingly, the FDA has never issued any document that declares
in a binding fashion that stevia is unsafe and cannot be sold,
only that it cannot be sold as a sweetener.
It has been observed that the study originally credited
with leading to the import ban on stevia was so badly done
that even distilled water would have been labeled a mutagen
under its conditions. Be that as it may, at one point results
of animal studies were adequate to raise the issue of whether
processes in the gut are sufficient to produce a mutagen from
stevia glycosides. The European Commission in 1999 banned
the use of stevia in the European Union until these questions
were answered. As of this writing, a variety of international and
national health bodies all have dismissed the earlier concerns
and given stevia a clean bill of health. Most recently, the
European Food Safety Authority issued its allowance in a 2010
safety review establishing an Acceptable Daily Intake (ADI) for
steviol glycosides expressed as steviol equivalents of four mg/
The United States now, as it were, is the “odd man out”
in its bifurcated assessment of stevia as safe as a dietary
supplement and potentially dangerous as a food additive.
As of 2008, this picture became more complicated in that
the FDA accepted that a particular extract of stevia can be
imported, labeled and sold as a sweetener. In that year, the
FDA gave a “no objection” approval for GRAS status to Truvia
and PureVia, both of which use stevia-derived rebaudioside A.
STEVIA FOR HEALTH
Today in the United States it is possible to purchase freely
stevia in various forms as a dietary supplement and in the
form of rebaudioside A as a sweetener. One issue of interest
is whether stevia is more than merely a sugar substitute.
Traditional use in South America with those suffering from
diabetes supports the argument that stevia is potentially useful
to those with blood sugar regulation issues. Modern research
shows that rebaudioside A possesses insulinotropic effects. As
noted in the outset, stevia supports blood glucose and insulin
regulation and may even be useful for blood pressure support.
In other words, stevia may be much more than merely a sugar
substitute for those hoping to escape sucrose, fructose and
artificial options. Sweet!