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STEVIA, STEVIA REBAUDIANA, ASTERACEAE, is native to the tropical and warm temperate zone of South America: Paraguay, northern Argentina and southern Brazil.
It is a small perennial plant, herbaceous then shrub after a few years, 50 to 80 cm high. Its light green crenellated leaves have a sweet flavor, its white flowers are discreet.

The Guarani Indians have known and used stevia for a long time as a sweetener in herbal teas, in particular mate tea (very bitter), a plant that comes from the same geographical area.
The Stevia rebaudiana or sweet grass of paraguay is also considered by the Amerindians as a medicinal plant it is the ka´a-he’e.

The consumption of « sugar », sucrose, glucose, fructose, is constantly increasing in the world, intentional consumption (coffee, tea, sweets etc.) or consumption without our knowledge (industrially prepared foods which contain sugary substances and salt, soft drinks).

Sweet foods are scarce in nature (fruit, honey) and it was not until industrial plantations of sugar cane and then sugar beet that sugar became a cheap flavoring. In addition, now much of the sugar used by the food industry comes from the chemical transformation of starch mainly from corn.

Following this increase in sugar consumption, a whole new pathology has developed: obesity and overweight, dental caries, type 2 diabetes (fatty diabetes), cardiovascular disorders linked to atherosclerosis.

Of course, not everything is due to sugar, but its role is important. To limit the consumption of sugar providing calories or to allow sweet eating for those for whom sugar is more or less prohibited (type 1 diabetes for example), chemists have developed chemical sweeteners, the most sold now is aspartame which is banned in several Asian countries because of its side effects on health.

The leaf of stevia rebaudiana and its extract (rebaudioside) have recently been recognized by the health authorities of the majority of « western » countries as an alternative to the use of synthetic flavorings or sugary substances based on glucose, sucrose or fructose

There are many species of Stevia in South America but there are only two « sweet » species, Stevia rebaudiana and to a lesser extent Stevia collina (Brazil). Other species of Stevia are often used in traditional medicines from South America.

STEVIA REBAUDIANA SUGAR GRASS FROM PARAGUAY NATURAL SWEETENER PREVENTION OF DIABETES OBESITY TOOTH CARIES

CHEMICAL COMPOSITION AND PROPERTIES

The Stevia rebaudiana leaf contains a complex mixture of 8 steviol heterosides (or steviosides) which corresponds on average to 15% of the dry weight (between 5 and 20% depending on the variety of stevia).

• Stevioside and rebaudioside A are the main constituents in percentage terms and for their sweetening properties.
  Rebaudioside A extracted from stevia is approximately 400 times more « sweet » than common sugar (sucrose) but without providing any additional calories.
  The fresh stevia leaf is also sweet as well as the dried leaf.
• Steviosides are fairly stable and therefore persistent compounds in the stevia leaf, they are soluble in hot water (infusion) and in hydroalcoholic mixtures (ethanol, liquor, beer, wine, etc.)

METABOLISM OF STEVIOSIDES

Steviosides are very poorly absorbed by the digestive mucosa, colonic bacteria hydrolyze them and release steviol.
The steviol is partly reabsorbed, the rest is eliminated in the faeces.
The steviol absorbed and transformed in the liver is found in the urine in humans (in the bile in rodents).
Stevia extracts do not accumulate in the body.

TOXICITY OF STEVIA EXTRACTS

Recent toxicological studies indicate that steviol heterosides (extracts of stevia rebaudiana) do not induce cancer, are not mutagenic and have no adverse effects on reproduction.

These studies were carried out mainly in rats (for 2 years and at high doses (almost 1g of stevioside per kg of weight and per day)) but we also now have the experience acquired by Asians (especially Japanese and Koreans) who have been consuming stevia for several decades without harmful side effects on their health.

These studies on the toxicity of stevia have been refined and extended because some detractors or lobbyists for sugar companies or aspartame manufacturers questioned the absence of toxicity of steviol, a metabolite of stevia extracts released in the intestine.

PHARMACOLOGICAL PROPERTIES OF STEVIA

TO REDUCE ARTERIAL HYPERTENSION

We cannot say with certainty that stevia lowers blood pressure, however some studies have had results in this direction (Chinese studies against placebo using 250mg or 500mg of steviosides orally 3 times a day), with improvement in blood pressure. quality of life and drop from 12 to 15 mm of Hg (example: systolic pressure which drops from 150mm to 135mm of Hg).
On the other hand, the toxicological study of stevia did not confirm this hypotensive effect.

TO IMPROVE TYPE 2 DIABETES

Here again contadictory results.
The toxicological study of stevia does not reveal any effect on the regulation of blood sugar, but other studies show that the heterosides of stevia, stevioside and rebaudioside A, activate the secretion of pancreatic insulin both in vitro and in vivo.

On the other hand, one thing is certain, the consumption of stevia reduces that of sugar and makes it possible to significantly reduce the daily calorie intake, a fundamental point in the treatment of type 2 diabetes.
It is perhaps this effect which makes it possible to say that stevia is antidiabetic as revealed by a Danish study where type 2 diabetics consume 1g of steviosides per day and see their diabetes improve.

ANTI-INFLAMMATORY AND ANTIBIOTIC STEVIA

A recent study reveals that stevioside is both anti-inflammatory and strengthens the body’s defense: attenuation of the synthesis of certain inflammation mediators and stimulation of the synthesis of TNFalpha (tumor necrosis factor).

Stevia extracts appear to be active against E. coli (colibacillus), staphylococcus aureus, diphtheria bacillus and candida albicans (yeast); this antibacterial effect seems to counteract the onset of dental caries.

USES

STEVIA AS A SWEETENER

Stevia and its extracts have been used for nearly 30 years in Asian countries (Taiwan, Japan, South Korea, China, Malaysia).
Conversely, and until very recently, stevia was ignored or prohibited from being marketed in the rest of the world, including in its country of origin.

The big food companies (especially in North America) realized that they could not stop the commercialization of stevia forever and that they would lose this lucrative market of natural sweeteners and sugar substitutes. They have therefore stopped their anti-stevia lobbying and are now working to promote stevia, to organize the production of stevia leaves, the commercial circuits and the use of stevia extracts in food products.

In France, since August 26, 2009, the use of a stevia extract as a sweetener has been provisionally authorized by an order for a maximum period of 2 years. Stevia extracts must contain at least 97% rebaudioside A (100% natural, calorie-free and 300 to 400 times sweeter than sucrose).

Another interministerial decree of January 8, 2010, published on Friday January 15, 2010 in the Official Journal, fixes the quantities of rebaudioside A that can be used as a sweetener in foods, drinks, « slimming products » and in diet food preparations intended for special medical purposes. This goes from 600 mg per liter for drinks (beer, fruit juice, milk, etc.) to 10,000 mg per kg for micro-confectionery (eg: refreshing pastilles).

In the European Union,: steviol heterosides have been authorized and regulated as food supplements since November 11, 2011.
The same is true in many countries.

In the USA, stevia extracts are authorized and regulated, but stevia leaf or stevia powder are still banned.

IN PRACTICE:

There are aqueous or hydro-alcoholic extracts of stevia (alcoholic tincture) and now concentrated extracts up to pure rebaudioside A, 400 times sweeter than sugar, and which does not have the « vegetable » taste of the extract. whole or dry leaf powder.

The concentrated extract of commercial stevia is in the form of a white powder, very light, odorless. To facilitate its use, this extract is often mixed with an inert substance which allows a better dosage in the diet.

You can use the green or dry leaf (20 times sweeter than sugar) as an infusion or by incorporating it directly into the liquid or solid food to be sweetened.
Fresh or dry stevia leaf has a more pronounced licorice aftertaste than rebaudioside A. The equivalent of a teaspoon of sugar corresponds to 1/4 or 1/2 teaspoon of dry powder of stevia leaves (depending on its percentage of stevioside) or one to 3 leaves of fresh stevia.

The consumption of stevia is particularly recommended:

• when following a low-calorie diet to lose weight or in case of type 2 diabetes,
• to limit sugar intake, a source of dental caries, colic disorders (irritable bowel syndrome) and disturbance of blood lipids in the event of an abnormality in triglycerides,
• or quite simply to « get rid of » sugar.
  The most obvious result of the use of stevia in a healthy person is a marked decrease in the attraction to sugary foods; this is usually accStevia and its extracts have been used for nearly 30 years in Asian countries (Taiwan, Japan, South Korea, China, Malaysia).
  Conversely, and until very recently, stevia was ignored or prohibited from being marketed in the rest of the world, including in its country of origin.

CULTIVATION OF STEVIA REBAUDIANA

You can very well grow stevia in your garden or on your balcony. It is sensitive to frost and drought but can withstand the mild winters of the Atlantic coast in Europe.

The propagation is done:

• in sowing seeds: many are sterile, 10-30% germination, seed life, not more than 6 months.
• by separating the root from the well-developed plant in the fall or by isolating the small secondary stems and their roots which develop in the spring.
• stem cuttings during the hot season
  Industrial plantations use more sophisticated methods: tissue culture and cuttings to obtain plants with a high yield of the active substance.

In spring, you can find young stevia plants in garden centers.

ABSTRACT

STEVIA A NATURALLY SWEET PLANT

STEVIA from South America is a natural sweetener.
Its sweetening power is very high and its consumption does not present any danger.
It is a good alternative to the use of aspartame.
Stevia may be hypotensive and mildly anti-diabetic.

Copyright 2023 : Dr Jean-Michel Hurtel

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