The many forms of stevia sweetener - whole leaf, stevia powder extract, or liquid

Stevia herb has been available to the American consumer as a dietary supplement since the mid 1980s. There are quite a variety of different forms and extracts being marketed. Which stevia products you want to use will depend on the amount of sweetness required by the recipe and the degree to which the particular recipe or beverage will benefit from the licorice-like taste that accompanies its less refined forms.

   If you shop at a health food or grocery store, you will generally find several forms of stevia herb and extract from a number of different manufacturers. Each stevia product may taste slightly different. Don't give up on stevia sweetener if you expect it to have the exact sweetness of sugar. It doesn't. However, when you consider the wonderful benefits it provides, you may accept its imperfections.

Fresh stevia leaves

This form of stevia is the herb in its most natural, unrefined state. It is possible to grow a stevia plant in your house or backyard. Just one word of caution. If you own a cat, you may not have too many stevia leaves left on the plant. They love to chew on it.
   For many centuries the Guarani Indians in South America used the leaves of stevia to sweeten their drinks. A leaf picked from a stevia plant and chewed will impart an extremely sweet taste sensation reminiscent of licorice that lasts for quite a while.

Dried stevia leaves

You can find the whole dried leaves of stevia in health food stores. For more of the flavor and sweet constituents of the stevia leaf to be released, drying and crushing are necessary. A dried stevia leaf is considerably sweeter than a fresh one, and is the form of stevia used in brewing herbal teas. When added to herbal tea blends, amounts can be adjusted to provide more or less of a sweet taste. Finely powdered or pulverized stevia leaf can be found both in bulk form and in tea bags. Several companies add stevia sweetener in tea bags with other herbs but do not mention that the stevia is for sweetening purposes since they are not allowed by the FDA to do so. These companies will instead call stevia a dietary supplement. Most of these products are currently found in health foods stores. 

   Stevia leaves have a greenish color and can be used as flavor enhancers or sweeteners in a wide variety of foods and beverages such as vegetables, coffee, applesauce, and hot cereals. However, in this form, expect stevia to have a more noticeable licorice-type aftertaste.
   If you are interested in extracting the sweetening agents from the leaves, bring two cups of purified water to a boil. Reduce the heat to medium and add one half ounce of crushed or powdered dried stevia leaves. Cover and boil for three minutes. Remove the covered pot from the heat and steep the herb until cool. Strain the water through a cheese cloth and refrigerate it in a covered container. The resulting liquid concentrate should be greenish black in color.
   As a rule, about 10 percent of the leaves contain stevioside and rebaudioside, the actual sweet glycosides of stevia. Although stevia leaves contain various vitamins, minerals, and phytochemicals, the amounts consumed are generally so minimal that the nutritional value will be negligible.

   Generally two to four leaves are sufficient to sweeten a cup of tea or coffee. For stevia to have a more practical application as a tea or sweetener, the leaves must be dried or put through an extraction process, which makes the sweet taste even more potent.

Green stevia powder

When the dried leaves are ground, they turn into a fine green powder which is generally about 10 to 20 times as sweet as sugar. You can convert this stevia powder into syrup by dissolving 1 teaspoon of the powder into 2 cups of filtered or distilled water. Then simmer this down into a thicker syrup then put it in a small bottle and refrigerate it to increase its shelf life.

   As a rule, the green stevia powder is not very popular due to its aftertaste. However, it is widely available in health food stores. The majority of recipes call for stevia extract as opposed to the green powder so double-check your recipe and make sure you have the right form.

White stevia extract

This is the form most commonly used for of stevia sweetener in Japan, and generally contains 85 to 95 percent of the sweet glycosides. In this form, it is close to 300 times sweeter than sugar. A teaspoon of this stevia extract has sweetening power equivalent to 2 to 4 cups of sugar. The sugar-type stevia packets found in many Japanese restaurants are bulked up with other substances (such as maltodextrin) since a much smaller amount of the extract itself is needed. Several companies in the US market stevia in small packets, similarly adding maltodextrin, xylitol, or other sweeteners or binders, fillers. Could stevia extract ever become so popular in the US that practically every restaurant in the country would offer packets of this sweetener alongside the pink packets of Sweet' N Low and blue packets of Equal?

   There are hundreds of patents for stevia herb extraction processes existing around the world. Various types of extractions influence the concentration of the various sweet glycosides, such as stevioside and rebaudioside, and therefore influence the stevia aftertaste. Thus, not all stevia powders and extracts are the same. You will find stevia extract in convenient stevia packets available for sale in a size similar to the artificial sweetener packets.

Stevia liquid concentrates
Stevia liquid comes in two distinctly different forms. One is a black, syrupy concentrate and the other is clear. The black, syrup-like stevia liquid concentrate is made by boiling the dried leaves in water. Traditionally, the Guarani Indians thought this crude liquid had medicinal benefits. It has a delicious taste that adds to the flavor of many foods, particularly hot beverages. A dropper-style stevia liquid bottle is the most common way that this form of stevia is found in stores. The clear type of stevia liquid concentrate is made by mixing a large amount of the white powder in distilled water or grain alcohol. Some of these liquid preparations contain other ingredients such as chrysanthemum flowers.

   All types of stevia liquid extract concentrates are available in health food stores or some retail outlets. They come in various sizes ranging from a third of an ounce to four ounce bottles. Generally a few drops of this stevia liquid concentrate is enough to sweeten a glass of tea, coffee or your favorite drink.

Safety of stevia - Is stevia a danger?

Stevia sweetener has been used as an ingredient in foods and drinks by South American natives for many centuries, and there is no report of any plant toxicity to the consumers. Stevia sweetener has been added to a number of food products in Japan since the mid 1970s. No indications of any significant stevia side effects have yet been reported after more than 30 years of use. Similarly, no reports of any adverse reactions to stevia herb have been reported in the United States. There are no indications at this point from any source that stevia herb has shown toxicity in humans.

Stevia side effects
As of January of 2008, no stevia side effects of any significance have been reported in the medical literature. We know of no one who has experienced any side effects using stevia sweetener. Stevia is a safe supplement.

Our daily stevia dose

It has been estimated that sugar consumption in Japan is about 80 grams a day while in the US and Europe it is between 120 to 140 g a day. Assuming we substitute stevia sweetener for sugar, what would be our daily consumption?      
   For the sake of simplicity, let's say we consume about 100 grams of sugar a day. Since the sweetness of stevioside is 300 times that of sugar, the maximum daily consumption of stevia would be 100 grams divided by 300, or a third of a gram (roughly 330 mg). Actually, Chinese researchers have already estimated that the daily human consumption of stevioside would be about 2 mg per kilogram of body weight. This is a very small amount and we should keep this in mind when we evaluate the toxicity studies with stevia herb done in animals. Another point to keep in mind is that most people would only partially substitute stevia for sugar and other sweeteners. Therefore, the intake of stevia sweetener on a daily basis would even be less than 330 mg.
   There have been a number of studies performed in rodents and other laboratory animals to determine whether stevia extract  has any toxicity. In many of these studies, stevia was provided in extremely high dosages, sometimes up to 5 percent of the weight of their food. Let's compare this to humans. Assuming we eat about two kilograms of food a day, and we ingest 200 mg of stevia, the proportion of stevia to our daily food intake would be about 0.01 percent; a very small amount, indeed.
   Let's examine a few studies done over the past two decades with stevia and stevia extract.

Animal Studies

Whenever researchers want to test the dangers of a substance they give it to laboratory animals such as mice or rats. They give progressively higher doses of the substance until a lethal dose (LD) is reached where 50 percent of the test animals die. This level is called the LD 50. Back in the 1970s, several research groups attempted to find the lethal dose of stevia rebaudiana. They discovered that, on average, a dose of 8,000 milligrams or more per kilogram of body weight was necessary to achieve this LD 50. In human terms, this would be equivalent to a 70 kg male ingesting more than 480,000 milligrams (or two pounds) of the extract. In most cases, a glass of water can be sweetened by less than 5 drops, an extremely minimal amount. As can be expected, no human has ever died from stevia overdose.

   In a study published in Japan in 1985, researchers determined that giving rats 550 mg/kg of body weight every day of stevioside for 2 years did not cause any abnormalities. However, could the ingestion of stevia cause abnormalities in the offspring? 
   In 1991, an excellent study was done by researchers at the Chulalongkorn University Primate Research Center in Bangkok, Thailand. The researchers wanted to study the consequences of daily ingestion of stevioside in hamsters and the effects on two subsequent generations. You may recall that stevioside is the main active sweetening agent in the stevia plant. Three groups of 20 one-month-old hamsters (10 males and 10 females) were force-fed daily with stevioside, while the fourth group stayed as the controls; they did not get any stevioside. The first group was given 500 mg per kilogram of body weight; the second group got a higher dose at 1,000 mg per kilogram of body weight, and the third group got the highest dose at 2,500 mg per kilogram of body weight. The experiment was started with 80 one-month-old hamsters, 40 of each sex, each weighing between 30 and 50 grams. The 2,500 mg per kg of body weight would be equivalent to a human ingesting 150,000 mg. The likely stevia amount most humans would ingest from sweetening their drinks and certain foods is often less than 500 mg.
   In the first generation, the average growth of the hamsters receiving various doses of stevioside did not differ significantly between each group. In the second generation, no significant difference in body weight was observed among groups of males receiving various doses of stevioside until 90 days of age. Thereafter, growth of males in the group receiving stevioside at 500 mg/kg of body weight was significantly higher than in the other groups. Nevertheless, male hamsters in the second and third groups grew the same amount as did the control group.
   In the third generation, at 120 days of age, no significant differences in body weights were observed in all groups of male and female animals. As to the mating performance, all three generations performed the same no matter what dose of stevioside they received. Their performance was equal to the controls.
  

Summary of the stevia safety Issue - Is stevia a danger?

One can study the influence of a particular chemical in an isolated Petri dish, or a test tube, or on rodents, ad infinitum but not know what this chemical will do in the human body when ingested in the small amounts normally consumed. In our opinion, having reviewed all the stevia safety studies published thus far, and considering the safe, centuries-old consumption in south America, and the more than three decades use of stevia herb by Japanese consumers, we conclude that stevia rebaudiana is safe for human consumption, particularly in the dosages normally consumed as a partial alternative to sugar, other natural sweeteners, and artificial sweeteners.
   In our opinion, the use of reasonable amounts of stevia poses no danger.

Benefit of stevia for diabetes

The availability of artificial sweeteners has been of enormous benefit to those with diabetes. However, there's always been a concern that over consumption of these synthetic sweeteners may cause some unknown harm to the body. Could mnatural stevia sweetener substitution be a good alternative for those with diabetes? We believe so. Stevia leaves have been used as herbal teas by diabetic patients in Asian countries. No side effects have been observed in these patients after many years of continued consumption. Furthermore, studies have shown that stevia extract can actually improve blood sugar levels.

   In 1986, Brazilian researchers from the Universities of Maringa and Sao Paolo evaluated the role of stevia in blood sugar. Sixteen healthy volunteers were given extracts of 5 grams of stevia leaves every six hours for three days. The extracts from the leaves were prepared by immersing them in boiling water for 20 minutes. A glucose tolerance test (GTT) was performed before and after the administration of the stevia extract and the results were compared to another group who did not receive the stevia extract. During a GTT, patients are given a glass of water with glucose and their blood sugar levels are evaluated over the next few hours. Those who have a predisposition to diabetes will have a marked rise in blood sugar levels.
   The volunteers on stevia extract were found to have significantly lower blood sugar levels after ingestion of stevia. This is a positive indication that stevia can potentially be beneficial to diabetics who substitute stevia in order to decrease their sugar consumption. Even if stevia by itself is not able to lower blood sugar levels, just the fact that a diabetic would consume less sugar is of significant importance in maintaining better blood sugar control.

   If you have diabetes, chances are you consume a large amount of artificial sweeteners. Switching to stevia herb is an option. Gradually use less synthetic sweeteners while substituting stevia. For instance, you can initially use stevia extract in some of your drinks, like coffee or tea. After a few weeks, if your comfort level with stevia herb increases, you can gradually use more of the herbal extract. Over the next few weeks and months you can either switch completely to stevia powder or liquid, or you can continue using it in combination with artificial sweeteners.

Benefit of stevia for weight loss

It would seem quite obvious that substituting a no-calorie sweetener to sugar would help reduce caloric intake and thus may contribute to weight loss. We are not aware of formal studies that have been done evaluating stevia substitution for sugar in relation to weight loss. If you are the type of person who adds sugar to your morning coffee or tea, or to iced tea, lemonade, and a variety of desserts and baked goods, then, over time, the elimination of these refined sugar calories could make a significant difference.

Benefit of stevia for blood pressure

In 1991, Dr. M.S. Melis, from the Department of Biology at the University of Sao Paulo in Brazil, gave a one-time high dose injection of stevia extract stevioside to rats and found that it caused a reduction in blood pressure as well as an increased elimination of sodium. A slight diuretic effect also occurred. Dr. M.S. Melis repeated a similar study in 1995. This time, he administered extracts of stevia to rats for 20, 40, and 60 days. After 20 days, there were no changes in the stevia treated rats compared to the control group (the ones that didn't receive the extracts). However, after 40 or 60 days of administering the stevia extract, there was a lowering of blood pressure, a diuretic effect was noted along with loss of sodium. The amount of blood going to the kidneys was increased.

   When normal human volunteers between the ages of 20 to 40 years were given a tea prepared with stevia leaves, a lowering of blood pressure occurred.