CHAPTER Three of The Stevia Cook Book

SWEET'N LOW EQUALS SACCHARIN:

Say, Are Synthetic Sweeteners Safe? 

Patent a synthetic sweetener, do some toxicity studies in animals that show it to be safe, send the results to the FDA, get their stamp of approval, and you're instantly a billionaire. It's that easy. Actually, even if this artificial sweetener is suspected of causing cancer in animals, and you happen to have a great lobbying team, you can still make your billions. But, if you happen to want to sell a natural product as a sweetener that's been used for centuries and has not shown to cause toxicity in animals and humans, good luck.

            There are three major artificial sweeteners sold in this country, saccharin, aspartame and acesulfame K. Let's briefly review their safety.           

Saccharin (Sweet 'N Low) is a zero-calorie granulated sugar substitute discovered in 1879 and up to 200 to 400 times sweeter than cane sugar. One packet contains the sweetness of two teaspoons of sugar. It is often added to soft drinks, gum, toothpaste, and foods such as dietetic canned fruits and salad dressings. It comes in a highly recognized pink packet with the very reassuring warning written in tiny letters that requires a high-resolution magnifier to read:

            "USE OF THIS PRODUCT MAY BE HAZARDOUS TO YOUR HEALTH. THIS PRODUCT CONTAINS SACCHARIN WHICH HAS BEEN DETERMINED TO CAUSE CANCER IN LABORATORY ANIMALS."

            Since 1981, saccharin has been listed in the US government's "Report on Carcinogens," after a Canadian study indicated it caused bladder cancer in laboratory animals. On October 31, 1997, the National Institute of Environmental Health, a government advisory panel, recommended that products containing this sweetener should continue to carry a warning label. An industry group called Calorie Control Council, which had sought a review of the warning, was not happy with this decision. They argued that the studies done on rats were not comparable to human use.

            In January of 1998, National Cancer Institute researchers announced that eating saccharin does not cause bladder cancer in monkeys. They tested 20 monkeys for as long as 24 years, giving them 25 mg per kg of body weight of saccharin five days a week. This dose was about five times of that allowed in humans. They were compared to a group of 16 monkeys who got no saccharin. Urine testing in the last two years showed no evidence of bladder cancer.

            It is still unknown whether long-term saccharin ingestion influences human tumor formation or whether it has any other long-term health consequences. For practical purposes, the ingestion of small amounts of this artificial sweetener should not be of concern.

Aspartame (NutraSweet, Equal) was approved by the FDA in 1981 and allowed in diet sodas in 1983. It has no warnings on the packet other than regarding its use by anyone with phenylketonuria (PKU), a rare inherited condition that afflicts one in 15,000 Americans. Uninformed consumers assume that they can use it with impunity, ingesting it directly or as a sweetener in hundreds of products. NutraSweet's parent company was the pharmaceutical giant Searle, which was later purchased by Monsanto.

            Discovered in 1965 in the course of ulcer-drug research, aspartame is comprised of phenylalanine, aspartic acid and methanol, or wood alcohol (which, when ingested, breaks down into formaldehyde). Aspartame has been the prime suspect for a variety of symptoms chronicled in thousands of consumer complaints to the FDA and the Dallas-based Aspartame Consumer Safety Network (see Resources). These include gastrointestinal symptoms, headaches, rashes, depression, seizures, memory loss, blurred vision, slurred speech, and other neurological disorders. Of course, just because a person feels a particular symptom in relation to timing of the ingestion of a particular substance doesn't automatically make this substance the culprit. It could just be coincidence.

            It's very difficult to pinpoint aspartame ingestion with symptoms of diseases since there are so many other chemicals, additives, foods, drinks, hormones, and other substances people ingest on a regular basis. However, the scientific community is starting to raise some concerns that aspartame may not be as benign as some would have us believe.

            At least two such scientists are Drs. John Olney and Nuri Farber, from the Department of Psychiatry at the Washington University Medical School in St. Louis, Missouri. In an article published in the November, 1996 issue of the Journal of Neuropathology and Experimental Neurology, they say, "In the past two decades, brain tumor rates have risen in several industrialized countries, including the United States... Compared to other environmental factors putatively linked to brain tumors, the artificial sweetener aspartame is a promising candidate to explain the recent increase in incidence and degree of malignancy of brain tumors. Evidence potentially implicating aspartame includes an early animal study revealing an exceedingly high incidence of brain tumors in aspartame-fed rats compared to no brain tumors in concurrent controls, the recent finding that the aspartame molecule has mutagenic potential, and the close temporal association (aspartame was introduced into US food and beverage markets several years prior to the sharp increase in brain tumor incidence and malignancy). We conclude that there is need for reassessing the carcinogenic potential of aspartame." (Olney, Farber, 1996)

            We called Dr. Farber in August of 1997 and he reaffirmed his position, "We have not changed our minds and still stand by our conclusions that the carcinogenic potential of aspartame needs to be reassessed."

            The FDA issued a statement regarding aspartame in November of 1996. The agency said, "A recently published medical journal article raises the question whether any increased incidence in the number of persons with brain tumors in the United States is associated with the marketing of aspartame.

            "Analysis of the National Cancer Institute's public data base on cancer incidence in the United States does not support an association between the use of aspartame and increased incidence of brain tumors.

            "The FDA stands behind its original approval decision, but the Agency remains ready to act if credible scientific evidence is presented to it."

            Aspartame, though, does have some advantages. In rat studies it has been found to not cause tooth cavities (Das, 1997), and its use as a substitute to sugar has lead to better weight control (Blackburn, 1997). However, similar benefits could potentially be obtained from stevia.

            In our opinion, the jury on aspartame is still out.

Acesulfame K (K stands for potassium) is known by the brand names of Sweet One, Swiss Sweet, and Sunette. It is contained in a few products including non-dairy creamers, instant coffee and tea, Jell-O sugar-free puddings and gelatins, Trident Sugarless Gum, Wrigley's Freedent, Diet Coke, and Diet Pepsi. Approved by the FDA is 1988, it is 200 times sweeter than sugar. Acesulfame K is a derivative of aceoacetic acid, a synthetic chemical, and is probably not metabolized by the body.

            Neither a health warning nor an information label is required for acesulfame K. The benefits or harms of the long-term use of this artificial sweetener in humans is currently not known.

Neotame, claimed to be 8,000 times sweeter than sugar, is a synthetic sweetener developed by the Monsanto Company, maker of aspartame. In 1998, the Monsanto Company applied to the FDA to market the product as a tabletop sweetener and as a sweetening ingredient in foods and beverages. The FDA approval process is expected to last two to three years.

            If approved, neotame could replace NutraSweet (Monsanto's brand of aspartame) which has faced intense price competition in major markets because patents that once covered it have expired.

Summary

The currently available artificial sweeteners have not been proven to be completely safe, nor have they been proven to be clearly harmful. We believe that partially, or mostly, substituting stevia for saccharin, acesulfame K, and aspartame, is a reasonable and prudent option for the consumer.

CHAPTER four of The Stevia Cook Book

The many faces of stevia

WHOLE LEAF, POWDER, EXTRACT, or LIQUID?

With stevia now permitted on the market as a dietary supplement, and poised to become an extremely popular product, there are quite a variety of different forms and extracts being marketed (even if none of them can officially be called a sweetener). Which stevia products you want to use will probably 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 the several forms of stevia from a number of different manufacturers. Each product may taste slightly different. Don't give up on stevia 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. For some people, appreciating stevia, just like wine, is an acquired taste.

Fresh 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 (see the resources section for companies that sell stevia cuttings). 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. In Bertoni's first official description of the stevia plant, he noted that "A fragment of the leaf suffices to keep the mouth sweet for an hour."

Dried Leaves

You can find the whole dried leaf 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 leaf is considerably sweeter than a fresh one, and is the form of stevia used in brewing herbal tea. 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 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 the 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 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 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 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 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 another substance (such as maltodextrin) since a much smaller amount of the extract itself is needed. One company in the US has also started marketing stevia in small packets, similarly adding maltodextrin. Could stevia 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 extraction processes existing around the world. Japan, itself, has over 150. Canadian researchers are hard at work to make a pure extraction process that they hope may completely eliminate the aftertaste. The type of extraction would influence the concentration of the various sweet glycosides, such as stevioside and rebaudioside, and could therefore influence its aftertaste. Thus, not all stevia powders are the same.

            Since extracted white stevia powder is so intensely sweet, we recommend that it be mixed with water and the solution used by the drop. You can dissolve 1 teaspoon of the powder with 3 tablespoons of filtered or sterile water. Once mixed, this solution should be stored in the refrigerator. You can then use it whenever you need a splash of sweetening when cooking. Generally one teaspoonful of this liquid solution, also called a 'working solution,' is roughly equivalent to one cup of sugar.

Stevia Liquid concentrates
These come in two distinctly different forms. One is a black, syrupy concentrate and the other is clear.

·         The black, syrup-like 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 bottle is the most common way that this form of stevia is found in stores.

·         The clear type of 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 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 concentrate is enough to sweeten a glass of tea, coffee or your favorite drink. With time, it's likely that stevia will appear on the shelves of grocery stores and pharmacies nationwide.

In Japan, and other countries that are familiar with the use of stevia, manufacturers have included this sweetener in several non-food products. These include toothpaste, gum and mouthwash. We hope that stevia will eventually be similarly used in this country.

CHAPTER five from the Stevia Cookbook

IS STEVIA SAFE?

Stevia has been used as a sweetening ingredient in foods and drinks by South American natives for many centuries, and there is no report of any plant toxicity to the consumers (Suttajit, 1993). Stevia has been added to a number of food products in Japan since the mid 1970s. No indications of any significant side effects have yet been reported after more than 20 years of use. Similarly, no reports of any adverse reactions to stevia have been reported in the United States. Donna and her family have been using stevia since 1990 without any health problems. There are no indications at this point from any source that stevia has shown toxicity in humans. However, it is still important that we review the available safety studies done thus far.

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 (Akashi). Assuming we substitute stevia 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 (Xili, 1992). This is a very small amount and we should keep this in mind when we evaluate the toxicity studies with Stevia 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 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 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.

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 (Kinghorn, 1985). 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 (Yodyingyuad, 1991). 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 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.

Microscopic examination of reproductive tissues from all experimental groups, both male and female, did not differ from the control group. The production of sperm was normal, even in the males who received the highest dose of stevioside. In the females, the ovaries of all the animals were perfectly normal.

In summary, no abnormalities were found in growth and fertility in both sexes. All males mated females efficiently and successfully. Females became pregnant after mating. The duration of pregnancy, number of fetuses, as well as number of young delivered each time from females in the experimental groups were not significantly different from those in the control group. The researchers say, "The results of this study are astonishing. Stevioside at a dose as high as 2,500 mg /kg of body weight did not do any harm to these animals. We conclude that stevioside at a dose as high as 2.5 grams per kilogram of body weight affects neither growth nor reproduction in hamsters. If this is true in other mammalian species including humans, this substance will be of great benefit to industry and medicine, and can be used more widely as a non-caloric sweetener in a variety of foods and drinks as already seen in Japan and Brazil."

The Latest Safety Study

"Assessment of the carcinogenicity of stevioside in rats," was the title of an article published in the June, 1997 issue of Food and Chemical Toxicology. We were very excited and anxious when we came across this study. Was this latest information going to show that stevioside was safe, or potentially harmful?

This latest study was performed by Dr. K. Toyoda and colleagues, from the Division of Pathology, National Institute of Health Sciences in Tokyo, Japan. For a period of 104 weeks (two years), three groups of rats were tested to receive either no stevioside (the controls), stevioside in a concentration of 2.5 percent of their diet, and stevioside in a concentration of 5 percent of their diet. There were 50 male and 50 female rats involved in the study. All surviving rats were killed at the end of week 108. The results showed the body weight of the rats was less in those who received the stevioside compared to the controls. This makes sense because stevioside has no calories. When the organs and tissues of the rats were examined under the microscope, there was no difference in the controls and those on stevioside, except females on stevioside had a decreased incidence of breast tumors, and the males had a lesser incidence of kidney damage. The researchers state, "It is concluded that stevioside is not carcinogenic in F344 rats under the experimental conditions described."

You may recall at the start of this chapter that we estimated an average person's daily dietary intake of stevioside to be, at most, about 0.01 percent of the total daily intake of food. It is reassuring that rats given significantly higher amounts of this sweetener did not have a higher incidence of tumors. Our interpretation of this research would lead us to believe that the small amounts of stevioside we consume daily to be extremely safe.

            As you can see, stevia appears to be extremely safe. Nevertheless, it was banned for import in 1991. Where the reasons justified?

The FDA's (Genuine?) Concern

Stevia leaves and extracts were banned from importation in 1991. What prompted the FDA to ban the import of this natural sweetener?

One possible explanation is the result of a 1985 laboratory study that hinted a biochemical breakdown product of stevia to be a possible health concern. This study was conducted at the College of Pharmacy, University of Illinois in Chicago (Pezutto). A strain of a bacterium called Salmonella typhimurium TM677, was exposed to stevioside and found not to have any problems. Many sweet-tasting chemicals related to stevioside were also found to not be of concern. However, steviol, a metabolite, or break down product of stevioside, caused some changes in the DNA of the bacterium. This only occurred in the presence of a liquid fraction derived from the livers of rats treated with a toxin called Aroclor 1254, and then exposed to NADPH. As you can see, this is getting a little complicated and farfetched. When steviol was given to the bacteria without first being exposed to the above toxins, there were no problems detected.

When humans ingest stevia, their livers are not first damaged by a toxin and then directly given steviol. Therefore, in our opinion, the above study has little, if any, relevance to humans and is best ignored in light of the long-term rodent studies discussed previously. Those studies are more practical and relevant. You may recall that when rodents are given stevia in massive doses for at least two generations, no side effects occur.

In case you have any concerns, a study performed in 1993 should comfort you. Researchers from the Department of Biochemistry at Chiang Mai University in Thailand, tested stevioside and steviol for mutagenicity (causing mutation, or changes in the DNA) using a strain of Salmonella typhimurium bacteria TA98 and TA100 (Suttajit). The sweeteners were also tested to see their effect on cultured human lymphocytes (types of while blood cells). The bacteria were cultured in a nutrient broth and then plated on a Petri dish or plate. Stevioside did not cause any mutations in either strains TA98 or TA98 at concentrations up to 25 mg per plate, but showed weak mutagenicity to only strain TA98 at an unusually high dose of 50 mg per plate. Even more important, no significant chromosomal effect of stevioside and steviol was observed in cultured human blood lymphocytes. The researchers state, "This study indicates that stevioside and steviol are neither mutagenic nor clastogenic [capable of causing damage to chromosomes] in vitro [in a test tube] at the limited doses." A similar study was repeated in 1997 at Mahidol University in Bangkok, Thailand. Stevioside and steviol were tested for mutagenic activity by the in vitro Ames test, a reincubation method, using Salmonella typhimurium TA 98 and TA 100 as the tester strains. Stevioside and steviol at the concentrations up to 50 mg and 2 mg per plate, respectively showed no mutagenic effect on both tester strains (Klongpanichpak, 1997).

Another concern is the possible influence of stevia on fertility and reproduction. A 1988 study conducted in Brazil indicated that female mice given stevia plant in the form of a tea during the mating period had a reduced rate of fertility (Nunes, 1988). The researchers say, "We believe that this effect of stevia is due to the stevioside present in the leaves, although other glycosides and/or substances that are not glycosides but are also present in the plant may confound the obtained results."

Since the availability of contraceptive research with stevia on humans is lacking, whether women trying to conceive can be similarly effected by stevia consumption is currently not known. For the time being, until formal human studies are conducted, it would seem prudent for women to reduce or minimize their stevia consumption before, and possibly during, pregnancy. It's unlikely that small amounts of stevia would have any significant effects on reproduction or the course of pregnancy.

Summary of the Safety Issue

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 safety studies published thus far, and considering the safe, centuries-old consumption in south America, and the two decades-plus use of stevia by Japanese consumers, we conclude that stevia is safe for human consumption, particularly in the dosages normally consumed as a partial alternative to sugar, other natural sweeteners, and artificial sweeteners.

            Having reviewed all the published studies on stevia that had been available in 1991, we did not encounter any that would justify the great lengths the FDA undertook to ban the import of stevia to this country. In our opinion, there seems to be enough evidence to suspect the FDA, for some reason, was biased towards stevia.  

Partial Excerpt from Chapter Five of THE STEVIA COOKBOOK by Ray Sahelian, MD and Donna Gates.

STAY HEALTHY THE STEVIA WAY

We all have a craving for a sweet taste and often satisfy this craving with sugar or fat-filled foods. Even "natural" sugar substitutes, such as honey, maple syrup or molasses, can be unhealthy if over-consumed since they can markedly elevate blood sugar levels. Hence, stevia can be advantageous to practically everyone whose diet contains sweeteners. Although stevia can be helpful to anyone, there are certain groups who are more likely to benefit from its remarkable sweetening potential. These include diabetics, those interested in decreasing caloric intake, and children.

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 stevia 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 (Suttajit, 1993). Furthermore, studies have shown that stevia extract can actually improve blood sugar levels (Alvarez, 1981, Curi, 1986).

       In 1986, Brazilian researchers from the Universities of Maringa and Sao Paolo evaluated the role of stevia in blood sugar (Curi, 1986). 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 extract and the results were compared to another group who did not receive the stevia extracts. 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 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 and you may be concerned about switching to stevia since long-term human studies have not been done with this herb. You may also be accustomed in your use of these artificial sweeteners and would not be willing to completely stop them. One option is to gradually use less of them while substituting stevia. For instance, you can initially use stevia in some of your drinks, like coffee or tea. After a few weeks, if your comfort level with stevia increases, you can gradually use more of the herbal extract. Over the next few weeks and months you can either switch completely to stevia, or you can continue using it in combination with artificial sweeteners. With time more research will become available on the safety of stevia and artificial sweeteners. Based on the results of these studies, you can determine which ones to continue using in a larger amount. It's also quite possible that artificial sweeteners may be safe in low amounts, but problems could arise when they are used in excessive quantities. By partially or mostly substituting stevia, you can reduce any potential risk. Stevia is a good supplement for those with diabetes.

Stevia and Weight Loss

It would seem quite obvious that substituting a no-calorie sweetener to sugar would help reduce caloric intake and thus contribute to weight loss. And such is the case with aspartame. Researchers at the Center for the Study of Nutrition Medicine, Beth Israel Deaconess Medical Center, at Harvard Medical School in Boston, Massachusetts, studied the influence of aspartame on obesity (Blackburn, 1997). One hundred sixty-three women were randomly assigned to consume or to abstain from aspartame-sweetened foods and beverages for 16 weeks. Both groups were also actively involved in a weight-control program using a variety of modalities. At the end of the 16 weeks, both the group on aspartame and the group without the synthetic sweetener lost 10 kilograms. During the maintenance phase that lasted the next two years, women assigned to the aspartame-treatment group gained back 4.5 kilogram, whereas those not on aspartame gained back 9.4 kilograms, practically all the weight they had previously lost. The researchers state, "These data suggest that participation in a multidisciplinary weight-control program that includes aspartame may facilitate the long-term maintenance of reduced body weight."

            Unfortunately, no formal studies have been done evaluating stevia substitution in relation to weight loss. We would suspect, though, that the results would be similar to the aspartame study discussed above. 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.

Sweet Teeth with No Cavities

Even a five-year old child knows that sugar causes tooth cavities. There are certain bacteria in our mouths, particularly streptococci mutans, that ferment various sugars to produce acids. These in turn eat through the enamel of the tooth causing pockets or cavities. For a long time, scientists have searched to find alternative sweeteners that are not fermentable by bacteria and hence do not cause cavities. Artificial sweeteners have been helpful in this regard.

            Does ingesting stevia lead to tooth cavities? A study done on rats has not shown this to be case. Stevioside and rebaudioside A, the two primary sweet constituents of the stevia plant, were tested in a group of sixty rat pups (Das, 1992) in the following way:

Group 1 was fed sucrose (table sugar), at 30 percent of their diet

Group 2 was given 0.5 percent of their diet in stevioside

Group 3 got 0.5 percent of their diet in rebaudioside A

Group 4 ingested no sugars.

            After 5 weeks, all four groups had their teeth evaluated. There were no differences in food and water intake and weight gain between the four groups. However, the first group had significantly more cavities than the rest of the groups. Groups 2, 3, and 4 were equivalent. 

The researchers state, "It was concluded that neither stevioside nor rebaudioside A is cariogenic [cavity causing] under the conditions of this study." It appears that the chemicals within the stevia plant that impart its sweetness are not fermentable, and thus do not cause tooth cavities.

Use in Children

Candies, sodas, ice cream, pies, cakes... it's disturbing how many sweet products are ingested by children on a daily basis. All that sugar can lead to tooth cavities and obesity. We believe that partially substituting with stevia can help children satisfy their sweet tooth while decreasing the risks from excessive sugar intake.

            If you're a parent, you can take advantage of the many recipes provided in the second half of this book to provide your children with tasty sweets that will satisfy their sweet teeth but not cause damage to the teeth. Obesity in children is a growing problem in this country and any method we have of helping children reduce their caloric intake will be greatly beneficial.

            We also are concerned with children overconsuming excessive amounts of artificial sweeteners. The potential, long-term health consequences of saccharin and aspartame ingestion are currently not fully known, but they do need to be kept in mind. Eliminating all artificial sweeteners will be a frustrating enterprise since they are extremely prevalent. However, by partially substituting stevia in homemade desserts, you can significantly reduce your children's exposure to these artificial chemicals.

            Hopefully, with time, stevia can be added to a variety of sodas, candies, gums, and other foods in the US, just like it currently is in Japan and other countries.

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 stevioside to rats and found that it caused a reduction in blood pressure as well as an increased elimination of sodium (Melis, 1991). A slight diuretic effect also occurred. The effect was additive when stevia was combined with verapamil (a medicine used to lower blood pressure in humans who have high blood pressure).

            Dr. 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 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 (Boeck, 1981). This study was done in Brazil. Certainly more human studies are needed before we can come to any conclusions regarding the full effect of normal daily ingestion of stevioside on blood pressure.

Use in Pregnancy or Breast Feeding

Since human studies providing stevia during pregnancy have not been done, we don't know whether its use during this period is safe. We suspect, though, that small amounts of stevia would not cause any problems. However, we will not know for certain until studies are completed.

Anti-Aging potential?

We know from numerous animal studies that reducing caloric intake leads to life span extension. Since stevia can substitute for sugar, and we know excess amounts of this sweetener can contribute to high blood sugar, obesity, and have other unhealthy effects on the human body, it would seem likely that substituting stevia for sugar could have a positive effect on longevity. This effect would be most apparent in those who normally have a high intake of sugar.

Glucose (sugar) has been implicated in the aging process by its ability to react with some proteins, like collagen, to produce glycation. That is, the glucose molecule attaches to some amino acids of a protein and makes the protein less functional, leading to disturbances within a cell. The initial phase of this attachment is called glycation.

            As we age, the amount of glycation of the proteins in our bodies tends to increase. We should also note that blood sugar generally increases as we age. It is known that glycation of human tendon and aortic collagen increases with age in proportion to the increase in blood glucose that occurs with aging (Schleicher, 1996 and 1997).

            This age-related increase in glycation, though, can be partially prevented by caloric restriction. In other words, avoiding high sugar consumption, and high caloric consumption, could theoretically, over the years and decades, help our proteins stay healthier. Practical ways to use this information include:

1) Eat small frequent meals throughout the day instead of one or two excessively large ones. Eating these small meals, or snacks, will help maintain your blood sugar at a relatively steady state, instead of wide fluctuations.

2) Make sure to have some protein with each meal. Avoid a purely carbohydrate meal, except if you are planning to induce sleep at night. Carbohydrates, eaten an hour or two before bed, help us get sleepy. Your carbohydrate intake should mostly be from unprocessed whole grains, vegetables and legumes.

3) Even relatively “healthy” drinks, such as fruit juices, can cause significant elevation of blood sugar when consumed in large amounts, such as 6 ounces or more. Many people quickly gulp down 8 ounces of orange juice in the morning, in addition to a cup of coffee laced with a teaspoon or two of sugar.

4) And, of course, substitute stevia for cane sugar whenever possible.