Stevia – what is it?

Stevia, sweet herb, sweet leaf, honey leaf, sugar loaf – five terms which describe the same thing, namely an alternative to harmful, calorie-rich household sugar and the highly questionably 'healthy' artificial sweeteners on the market.

For simplicity's sake, we will refer to it using the most common of all designations in this text: STEVIA.

The name 'stevia' comes from its origin, namely 'Stevia rebaudiana' (Eupatorium rebaudianum), a plant type from the Stevia genus of the Asteraceae family.

Stevia, a sweet medicinal plant as a healthy sugar substitute

'Stevia rebaudiana' originates from the sub-tropical annual plants and grows to about 70-100 cm tall. It has 2-3 cm-long leaves and white flowers. When raw, i.e. unprocessed, the stevia plant stands out by developing 10 to 30 times more sweetness compared to household sugar, depending on the surroundings and climate. As a processed extract, it even has 300 to 400 times more sweetness.

 

What makes stevia so sweet?

Stevia owes its pronounced sweetness to its complex molecule, called stevioside, a glucoside from glucose, steviol and sophorose. In conjunction with other ingredients which are related but some of which have not been studied down to the last detail, the stevia leaf appears to be 10 to 20 times sweeter than sugar. 

Origin and history of the stevia plant

The original name of the stevia plant comes from Paraguay in South America and it is thanks to its impressive sweetness and health benefits that it has been used by the native inhabitants of Paraguay and Brazil for centuries as both a sweetener and medicine. The Guarani and Mato Grosso Indians have used stevia for centuries as a sweetener for their slightly bitter Mate tea and in other dishes and also as a medicine, to heal wounds and for diabetes among other things.

The sweetening properties and health benefits of stevia were revealed to Europeans as far back as the 16th century when the Spanish conquistadors first reported that the native South Americans used its leaves to sweeten their herbal tea.

Is stevia therefore a health-promoting alternative to unhealthy sugar and artificial sweeteners? Yes. We will look at this more closely later...

 

Stevia cultivation

Despite its tropical origins, the stevia plant is characterised by a relative lack of sensitivity to temperature. Thus, Stevia rebaudiana can also be cultivated on our latitude; however, when cultivating seeds, a continuous germ temperature of at least 22 °C should be ensured.

For this, sow the seeds in the compost in a bowl and then place it on the surface of the soil (stevia is a light germ so do not cover it with soil) and lightly press. The slightly damp soil is covered with a glass or film and the bowl is kept in a light, warm location (for example, a window ledge, heat in the winter!). After about ten days, the first seedlings should appear.

As soon as the plants are there, each one must be transferred into its own pot with highly permeable soil. At this point, ensure that the pot is the right size (approx. 16 cm) so that the plant can spread out its storage roots. Similarly to basil, the stevia plant flourishes in a varied environment of moisture and dryness; however, standing water (in the tray) should be avoided as far as possible.

Scientific studies on stevia

The first scientific realisations regarding stevia were made by the botanist Moisés Santiago Bertoni who travelled from Tessin to Paraguay and presented it in his scientific treatises in 1899. Since then, stevia has been researched across the world, which has led to the approval of stevia in many countries including Japan, New Zealand, Australia and recently also in Switzerland.

Stevia has also been intensively researched in Germany, for example since 1998 at the University of Hohenheim. Field tests have been carried out with stevia in the Rhineland since 2002.

Stevia in cancer studies

Contrary to the initial and now discredited theory that stevia could cause cancer, several studies on animals reinforce the very opposite (for example the studies of Hagiwara et al. (1984), Yamada et al. (1985), Xili et al. (1992) and Toyoda et al. (1997), namely that stevioside causes a clear inhibition of tumour development. 

Furthermore, Konoshima and Takasaki were able to prove in 2002 that stevioside inhibited the formation of skin cancer in animal trials.

The authors of this study concluded from this that stevioside is a valuable sweetener which could be suitable as a protection against chemically triggered cancer.

Stevia in blood pressure studies

In a study by Chan et al. (2000), 60 test subjects with high blood pressure were prescribed 250 mg of stevioside 3 x a day for a duration of one year. After three months, the systolic and diastolic blood pressure of the test subjects had significantly decreased and the effect was sustained for the entire year.

The values at the start of the study were, on average, 160 mmHg systolic and 102 mmHg diastolic, while, by the end of the study, the blood pressure sank to an average of 153/90 mmHg.

Neither the blood parameters (lipids and glucose) nor the quality of life changed and no harmful signs were observed. The authors of the study determined from this that stevioside is a tolerable and effective substance for use within nutritional supplement treatments of patients with high blood pressure.

Stevia in fertility studies

The initial scepticism that stevia could negatively influence our reproductive organs was refuted by Shiotus (1996). No negative influence was observed in the reproductive organs of rats, mice or hamsters.

This was confirmed in a study by Oliveira-Filho et al. (1989).

Studies regarding the maximum dose of stevia

'The dose makes the poison' – a saying which affects all foodstuffs, even pure water (in adults more than 10 litres at once due to hyponatraemia[1]). With stevia, too, there is a tolerance level. A study (Xili et al., 1992) calculated a permissible daily dosage of 7.9 mg of stevioside per kg of body weight, which would still mean 592 mg of pure steviol a day for a person weighing 75 kg.

If we work on the basis that the total average sugar consumption per day (131 g/day) should be replaced by stevioside (which is practically impossible), this could be achieved with less than 436 mg of stevioside or 4.36 g of dried stevia leaves.

A daily dosage of 20 mg/kg body weight could be derived from various toxicological studies with a safety factor of 100.[2] Study results in Japan and Brazil showed that no toxicity should be expected with the daily consumption of less than 38.5 mg of stevioside/kg of body weight.[3] In April 2010, the European Food Safety Authority classified up to 4 mg per day per kg of body weight as harmless.[4]

The JECFA study by the World Health Organisation

The JECFA (Joint FAO/WHO Expert Committee on Food Additives), an expert commission for foodstuff additives which belongs, among other organisations, to the World Health Organization, published a study in 1999 which confirmed that the oral consumption of stevioside with a concentration of 2.5 % demonstrated no significant toxic effect in rats over two years. This corresponds to 970-1,100 mg of stevioside per kg of body weight. In addition, the JECFA and the WHO determined a temporary ADI VALUE ('acceptable daily intake') for steviol-glycoside at their 69th meeting, providing worldwide confirmation of the harmlessness of stevia to our health. Unlike with sugar and artificial sweeteners, centuries of use of stevia across the world have not resulted in a single known case of poisoning or other health impairments from the use of stevia.

The decisive approval study in the EU

While there are still some individual health reservations to be discussed, on 14 April 2010, the European Food Safety Authority (EFSA) classified stevia as neither genotoxic nor carcinogenic, without any negative effects on human fertility and reproductive organs, based on current studies. The realisations made about the harmless nature of stevia on the part of the EFSA in April 2010 made an imminent approval of sugar substitutes from stevia in the EU highly likely.

Market cultivation and approval of stevia sugar substitute – Japan as a pioneer

It is estimated that approx. 150 million people across the globe use stevia daily, in particular in Japan, China, Malaysia, Korea, Thailand and South America but also in the USA, New Zealand, Israel and Mexico. Korea has been producing stevia for the Japanese market since 1973 and it has been permitted as a sweetening agent on the world market since 1975. There, it has already been able to conquer 50 % of the sweetening agent market and so it is understandable that stevia has been used as a sweetener in things such as ice cream and lollies as well as cakes, biscuits, lemonade, milk products and toothpaste for over 30 years.

In June 2008, the UN panel of experts classified stevia as harmless to health following extensive research, which quickly led to the approval of stevia sugar substitute in Switzerland.

France was the first EU state to issue a 'temporary' approval for stevia sugar substitute, initially limited to two years.

 

Approval by the FDA in the USA

The FDA (Food And Drug Association in the USA), concluded that stevia is a harmless foodstuff with high nutritional value and approved it in the USA.[5]

Stevia officially classified as harmless in Europe

Stevia is still classified as a 'novel food' in the EU; a new type of food stuff which must provide clear proof that it is harmless.

Stevia now also approved in the EU

After years of efforts and enthusiastic campaigning, stevia has now also been approved as a foodstuff supplement in the EU since 2 December 2011 under the identifier E960. However, this does not mean the stevia plant, rather the artificially created substance! (See 'Stevia lies')