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Stevia: Health Benefits, Facts, Safe
Stevia rebaudiana is a South American plant of
the Asteraceae family, which also includes sunflowers and chrysanthemums.
Native to Paraguay,
stevia has traditionally been used to sweeten beverages and make tea. The term
"stevia" refers to the entire plant and its components, only some of
which are sweet.1
While the word "stevia" refers to the entire plant,
for the purposes of this article, the term "stevia" will be used
interchangeably to also refer to "steviol glycosides" - the sweet
components isolated and purified from the stevia leaves.
This article looks at what stevia is, how it is extracted, its
health benefits, how it is used, whether it is safe and its current regulatory
status. You will also see introductions at the end of some sections to any
recent developments that have been covered by MNT's news stories. Also look out
for links to information about related conditions.
Fast
facts on stevia
Here are some key
points about stevia. More detail and supporting information is in the main
article.
§ Stevia is a plant naturally grown in Brazil
and Paraguay.
§ Stevia is much sweeter than sugar - the
extract can taste 250-300 times sweeter than table sugar.
§ The extract is contained in a number of food
items in the US such as energy bars, candies, protein drinks and some teas.
§ Since stevia is so much sweeter than sugar, recipes
require less of it.
§ Stevia does not brown and caramelize the same
way sugar does.
§ Stevia is calorie-free, but that does not
necessarily mean you will lose weight if you swap sugar for stevia.
§ Based on the stevia nutrition facts,
it is the 10.77% fiber which helps in curing constipation and promotes proper digestion.
§ One of the benefits of stevia is that it
contains a 702 ppm level of iron which can stimulate the production of
hemoglobin.
§ Stevia and other artificial sweeteners that
have been approved for use in the US do not appear to pose any health risks
when used in moderation.
What is stevia?
Stevia plants grow and are harvested in many countries around
the world, predominantly in China and Brazil. The plants grow 2-4 feet in
height with slim, branched stems, and thrive in temperate and some tropical
regions. Stevia is grown by natural, conventional plant breeding methods such
as cross-pollination and other non-genetically modified processes.
Stevia is an intensely sweet natural sweetener that is harvested around the world from the stevia rebaudiana plant.
The plant is
cultivated as a commercial crop in Japan, China, Kenya, Vietnam, India,
Argentina, Colombia, Thailand, Paraguay, and Brazil. Currently, China is the
leading exporter of stevia products.8,19
Stevia provides an important role in biodiversity due to how
little land is required to grow it, allowing farmers to diversify their crops.
Unlike commodity crops, stevia is grown on smaller plots of land and provides
supplemental income to more commonplace crops.
As stevia is intensely sweet and an extract, it typically
requires only a fifth of the land and much less water to provide the same
amount of sweetness as other mainstream sweeteners. For example, in Kenya,
stevia is typically grown on only a third of the land, with the rest of the
land being devoted to other crops.
In a 2013 study, the carbon footprint of stevia was shown to be
79% lower than high fructose corn syrup (HFCS), 55% lower than beet sugar, and
29% lower than cane sugar, based on industry production standards.
There are 150 species of stevia, all native to South and North
America. The sweetness of the stevia leaves is caused by eight glycosides
contained within them. These glycosides are stevioside, rebaudioside A, C, D, E
and F, steviolbioside, and dulcoside A. Stevioside is the most abundant of
these components; the leaves of some cultures contain up to 18% stevioside.
Although it was not until the 19th century that scientists began
seriously investigating stevia, the indigenous people of Paraguay were using
the plant as early as the 16th century to sweeten drinks and medicines.
During his studies of herbs used as sweeteners by native people,
Dr Moises Santiago Bertoni, a Swiss botanist of Italian descent, is credited
with having notified the world of stevia's existence.
French chemists identified stevioside in 1931 and its use
expanded. In the 1950s, Japan began growing the stevia plant as a crop.
Countries with a history of using stevioside as a no calorie
sweetener include Japan, China, South Korea, Taiwan, Israel, Brazil, Uruguay,
Paraguay, Columbia, Thailand, Germany and Malaysia.
Some of the common and trade names for stevia sweeteners are
Enliten, PureVia, Rebaudioside A/Reb A, Rebaudioside B, Rebaudioside C,
Rebaudioside D, Rebiana, Stevia, Steviacane, Steviol Glycosides, Stevioside,
Stevia Extract In The Raw, and SweetLeaf.
Health benefits of stevia
Steviol glycosides
have zero calories.
Stevia-based tabletop sweeteners can have zero or minimal calories per serving,
depending upon the other food ingredients with which they are combined. These
factors could have a positive effect on those looking to control weight or
manage diabetes.
Stevia also contains
certain vitamins (A, B, C), minerals (iron, zinc, calcium),
electrolytes (sodium, potassium), proteins, and other elements.21
Below, we take a look
at the possible health benefits of stevia.8
1) Diabetes
Research indicates that stevia sweeteners do not contribute
calories or carbohydrates to the diet and do not affect blood glucose or
insulin response.
Research has shown
that stevia sweeteners do not contribute calories or carbohydrates to the diet and do not affect blood glucose or insulinresponse,
which allows people with diabetes to consume a wider variety of foods and
comply with a healthful meal plan.
A randomized controlled trial over 16 weeks had 122 participants take
four doses of approximately 330 mg of steviol equivalents over the course of a
day. Compared toplacebo, there was no impact on blood sugar levels. For this study,
>97% rebaudioside A was used.
Additionally, a position paper on nutritive and non-nutritive
sweeteners from the Academy of Nutrition and Dietetics reviewed five randomized
controlled trials examining the effects of stevia compared with placebos on
metabolic outcomes.
The studies reported
minimal to no effects on blood glucose, insulin levels, hypertension and body
weight. In one study showing
minimal effects, subjects with type
2 diabetes reported reduced
postprandial blood glucose and glucagon response after a test meal of stevia
versus placebo.
2) Weight control
The causes of
overweight and obesity around the globe are quite complex and
include factors such as an increase in physical inactivity due to increased
sedentary time and increased intake of energy-dense foods that are high in fat
and added sugars.
The intake of added
sugars has been shown to contribute an average of 16% of the total calories in
the American diet, and has been linked to weight gain and adverse effects on
glycemic control.11
Plant-based, zero calorie stevia can be part of a well-balanced
diet to help reduce energy intake without sacrificing taste.
Replacing just 25g (about 6 teaspoons) of nutritive sweeteners
in foods and beverages can provide a 100-kilocalorie reduction.
3) Metabolism
Steviol glycosides are poorly absorbed in the body and pass
through the upper gastrointestinal tract, including the stomach and small
intestines, fully intact.
Once steviol glycosides reach the colon, gut bacteria hydrolyze
steviol glycosides into steviol by snipping off their glucose units. Steviol is
then absorbed via the portal vein and primarily metabolized by the liver,
forming steviol glucuronide, before being excreted in the urine.
Research has shown that there is no accumulation of stevia (or
any byproduct of stevia) in the body during metabolism. It is a result of this
essentially poor absorption in the digestive tract which ultimately contributes
to the fact that stevia has zero calories and does not raise blood glucose or
insulin levels when digested.
4) Pancreatic cancer
Stevia plant has many
sterols and antioxidant compounds like triterpenes, flavonoids,
and tannins. Some of flavonoid polyphenolic anti-oxidant phytochemicals present
in stevia are kaempferol, quercetin, chlorogenic acid, caffeic acid,
isoquercitrin, and isosteviol. Studies have found that kaempferol can reduce
the risk of pancreatic
cancer by 23% (American Journal of Epidemiology).
5) Blood pressure
Certain glycosides in
stevia extract have been found to dilate blood vessels, increase sodium
excretion, and urine output. In effect at slightly higher doses than as a
sweetener, stevia can potentially help lower blood pressure.
The plant may have cardiotonic actions, which normalize blood
pressure and regulate heartbeat. The plant displayed vasodilatory actions in
both normotensive and hypertensive animals.
6) Special populations
Regulatory health agencies around the world have approved high
purity stevia leaf extract for safe use. This includes special populations such
as pregnant and nursing women, children and people with allergies or diabetes.
7) Children
Foods and beverages containing stevia can play an important role
in decreasing calories from unwanted sweeteners in children's diets. There are
now thousands of products containing naturally-sourced stevia on the market,
ranging from salad dressing to snack bars, that allow children to consume foods
and beverages that taste great without added calories.
Multiple global regulatory organizations, including the Food and
Agriculture Organization of the UN (FAO) and World Health Organization's (WHO)
Joint Expert Committee on Food Additives (JECFA), European Food Safety
Authority (EFSA), and the Food & Drug Administration (FDA) have determined
that high purity stevia extract is safe for consumption by the general
population including children, when consumed within the recommended levels.
8) Allergies
In 2010, the EFSA reviewed literature to determine if there was
any cause for concern regarding the potential for allergenicity of the stevia
plant. The reviewers concluded that "steviol glycosides are not reactive
and are not metabolized to reactive compounds, therefore, it is unlikely that
the steviol glycosides under evaluation should cause by themselves allergic
reactions when consumed in foods."
Additionally, while there is no scientific reason to suggest
genetically modified crops or "GMOs" cause allergies, it is worth
pointing out that stevia plants are not genetically modified, and therefore
there should be no concerns regarding potential for allergenicity.
Other uses
Stevia extract has
exhibited strong bactericidal activity against a wide range of pathogenic
bacteria, including certain Escherichia coli strains.
Steviol was observed to be mutagenic toward Salmonella and
other bacterial strains under various conditions and toward certain cell lines.
Stevia may also be
effective against Candida albicans and has shown
some anti rotavirus activity. Stevioside has shown promising immunomodulating
effects in rats and cell lines. In addition, stevia may have
antiproliferative/antimutagenic/antioxidant properties. One report addresses
stevia's role in reducing dental plaque.
Is stevia
safe?
Stevioside, a main
glycoside of stevia, was found to be nontoxic in acute toxicity studies in a
variety of laboratory animals.21
Independent scientific experts in both the US and globally have concluded that stevia sweeteners are safe for people of all ages and populations.
No major contraindications, warnings, or adverse reactions have
been documented.
In 2008, the FDA
declared that stevia was safe in foods and beverages. The US may see numerous
companies incorporate it into their products since there is considerable
consumer interest in natural, low, or no calorie sweeteners.7
Studies clearly support the safety of stevia sweeteners.
Further, clinical studies show that steviol glycosides, meeting purity criteria
established by the JECFA, have no effect on either blood pressure or blood
glucose response, indicating stevia sweeteners are safe for use by individuals
with diabetes.
Based on the wealth of published research, independent
scientific experts in both the US and globally have concluded that stevia
sweeteners are safe for people of all ages and populations and an Acceptable
Daily Intake (ADI) of four mg/kg body weight (expressed as steviol) has been
established.
Stevia leaves naturally
contain sweet compounds called steviol glycosides. High purity stevia leaf
extract, the ingredient form approved for food and beverage by regulatory
authorities, contains 95% or more of these steviol glycosides. It is this high
purity form that has been tested rigorously in more than 200 scientific studies
and approved for human consumption by multiple major regulatory organizations
around the globe.10
Multiple, major global
regulatory organizations, including the Food and Agriculture Organization/World
Health Organization's Joint Expert Committee on Food Additive (JECFA), the
EFSA, the FDA and Food Standards Australia New Zealand (FSANZ), have determined
high purity stevia leaf extract to be safe for consumption by children, adults
and special populations.15
Regulatory
status
In order for a new food or beverage ingredient to enter the US
food supply, the ingredient must either be a FDA approved food additive or
GRAS. The quality and quantity of scientific evidence required for a substance
to achieve GRAS status are the same as for FDA food additive approval.
Stevia leaf extract has been
evaluated and approved for use as an ingredient in food and beverages by
multiple regulatory agencies throughout the world, and can even be used on your
breakfast pancakes!
In December 2008, in
response to GRAS notifications submitted to the US FDA, the FDA stated it has
no questions regarding the conclusion of expert panels that rebaudioside A is
GRAS for use as a general purpose sweetener in foods and beverages, excluding
meat and poultry.4
In June 2009, FDA stated it has no questions regarding the
conclusion of an expert panel on the GRAS status of another steviol glycoside
extract with high rebaudioside A content for use as a tabletop sweetener.
In 2010, the EFSA assessed the safety of steviol glycosides from
stevia and established an ADI for their safe use. In November 2011, the
European Commission authorized the use of steviol glycosides as a sweetener in
foods and beverages.
Stevia sweeteners are approved for use in many other countries,
including Korea, Mexico, Japan, Paraguay, Taiwan, China, Russia, Australia,
Argentina, New Zealand, Colombia, Peru, Uruguay, Brazil and Malaysia.
The majority of scientific research on stevia uses high purity
stevia extracts. Confusion has resulted in the past when research conclusions
about stevia were drawn based on studies testing crude stevia extracts.
In some countries, crude stevia extracts or whole stevia plant
leaves are often sold as dietary supplements, but it is important to note that
only high purity stevia leaf extract has been evaluated and approved for use as
an ingredient in food and beverages by multiple regulatory agencies throughout
the world.
Around the world, stevia is listed differently due to
regulations from country to country. This is because different countries have
their own established food policies on stevia and labeling policies vary from
country to country
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