Stevia: All about a sweet miracle plant

Stevia is a no-calorie natural sweetener from the plant Stevia Rebaudiana grown in abundance in countries like Brazil and Paragua in South America. This plant is commonly known as “Sweet Grass of Paraguay”. The native people call it Kaa-hea, Caa ehe, Jae- jea etc.

It is a perennial grass. For centuries it has been used by native Indians of South America to mask the bitter taste of medicines, to sweeten drinks and for other medicinal purposes, such as to regulate blood sugar and hypertension.

In 1887, a South American Scientist Dr Moies Santigo Bertoni, Director of the college of agiculture in Asuncion, first described the biological properties of Stevia. In 1900 Ovidio Rebaudi first isolated the active ingredients, glycosides, responsible for sweetness of Stavia leave extract.

The characterisation of different glycosides of Stevia was completed in 1931. Stevioside, the sweetest glycoside of Stevia, is 300 times sweeter than sucrose. The concentration of stevioside in the leaves increases when the Stevia plants are grown under long days and when these plants are harvested just prior to flowering.

Cultivation of Stevia started in 1961. Today a number of countries like Japan, Canada, Malaysia, China, Korea, Mexico, United States of America, Indonesia, Tanzania, Brazil, Paraguay are involved in commercial production of Stevia. All of these countries grow Stevia as one of its vegetable crops.

Today China is the biggest producer of this plant. India is actively pursuing its efforts to commercially grow Stevia. Stevia is a semi-humid subtropical plant which can be easily grown like any other vegetable. Since 1990s, Japan has become the major market for Stevia.

For a long time the United States Food and Drug Administration (FDA) had refused to provide the status of GRAS (generally recognized as safe, such as starch) to Stevia citing the fact that the safety of the product has not been adequately studied or established under controlled conditions in humans. They simply tended o refuse the truth that the product has been consumed by people for centuries in South America without demonstrating any ill effects.

The pressure on FDA was probably exerted by the influential groups with vested interests, such as industries involved in producing artificial sweetener. The group associated with the huge market for soft drinks or non-alcoholic beverages that use large quantities of sugar and fructose (mainly from corn syrup) also did not tend to welcome Stevia.

As such, it took a long time for USA to recognise Stevia as a valid natural sweetener and to provide the status of GRAS. Similarly, “PureCircle”, the world’s leading producer and marketer of high purity Stevia, had welcome the approval of Stevia by Health Canada for use in foods and beverages in Canada.

Biological properties and use of Stevia?

As a Sweetening Agent: Stevia leave powder is 20-30 times sweeter than cane sugar. Stevioside, the isolated glycoside from leave extract, is 300 times sweeter than sugar. There are usually two broad categories of sweeteners used in food and drug industries: carbohydrate sweeteners and non-carbohydrate sweeteners. Carbohydrate sweeteners include: sucrose, fructose, glucose, sorbitol, mannitol, starch syrup, corn syrup etc.

The non-carbohydrate sweeteners can be divided into two groups: a) those that are chemically and artificially synthesized and b) those that are obtained from plants. The members of the former group include saccharine, aspartame, sucralase etc and the members of the latter group include steviosides, thaumatins and monellins. Stevioside is getting popular by the day because of its natural source and safety features.

Obesity, Diebetes, “Metabolic Syndrome”, “Cancer” and the Role of Sugar: The rise of obesity in the western countries, especially United States, and among the economically privileged sections of developing countries can be traced to a combination of increased caloric intake and lack of physical activities.

When analysed thoroughly, it became evident, that at least in the United States the root of obesity is due to excess caloric intake from sugar, especially in the form of soft drinks or beverages that contain high amount of sucrose and fructose (especially from corn syrup).

In the US fructose now constitutes 10 percent of total calorie intake which is significantly higher than that of the percentage of caloric intake through fructose a decade ago. The excessive body weight resulted in diabetes and metabolic syndrome in epidemic proportion in the United States.

The term “metabolic syndrome” describes a condition that represents concurrent presence of obesity (especially abdominal obesity), insulin resistance, hypertension, abnormal lipid profile and may be also non-alcoholic fatty liver, elevated inflammatory response etc. There also remains a positive relationship between obesity and the development of cancer, especially certain types of cancers, such as cancer of colon, rectum, breast, pancreas, esophagus, stomach, gall bladder, liver, kidney, ovary etc.

Since stevioside does not contain any calorie, the use of this sweetening agent either in food or medicine could have a significant potential in reducing obesity and obesit- related diseases and metabolic disorders.

Steviosides against dental caries: Dietary sucrose has been implicated to cause dental caries. It is believed that sugar substitutes can reduce the incidence of dental caries. Stevioside has been found to reduce dental caries. It may exert its action by three different ways: a) antibacterial effect, b) production of low acidic condition and c) anti-plaque activity.

Other effects of Steviosides: Although not established in humans yet, following properties of steviosides have been established in animals both in vivo and in vitro:

Antioxidant properties
Antibacterial, antiviral and antifungal properties
Anti-inflammatoy effects
Chamopreventive and anticacinogenic properties
Antihypertensive effect
Effective against inflammatory bowel syndrome
Antifertility effects

Among all these effects mentioned above, a mild antihypertensive property of stevioside has been established in humans as well.

Switzerland has recently started producing chocolate bars with Stevia extract as sweetener and the product is being marketed all over the world including in the Indian Sub-continent. Natural sweetener pills containing stevioside are now available in a number of countries.

Like other sugar substitutes, they are also dispensed in small containers to carry in the pocket or purse for everyday use with tea, coffee or other food items by people on the go. A number of products related to tooth hygiene including toothpaste and mouthwash are being produced with ingredients that contain steviosides to prevent tooth decay.

As far as safety of Stevia or stevioside is concerned, it has been tested for centuries in humans as the plant has been in use by South American Indians for hundreds of years in bulk quantities. The taste or looks of food do not change with the addition of steviosides. As such, the use of steviosides as food additives is quite acceptable by the public and its popularity as a food additive is getting momentum in the United States.

In well-controlled paired studies, the safety and non-toxicity of Stevia products have been established using high doses. Genetic testing after its use for a prolonged period indicated that neither steviosides nor other ingredients of Stevia plants had shown to react with DNA or to produce DNA damage.

In the present obesity crisis and its multiple effects on overall health, there is a tremendous potential of non-caloric natural stevioside as a sweetening agent. Its other pharmacological properties will be highlighted upon completion of well-controlled human studies that have been initiated based upon positive results obtained in animal models.