The following is an excerpt from The Global Stevia Institute newsletter: We have been talking to health professionals across the world to ensure that you have stevia facts you need to know based on current research and expertise. Here we answer the Global Stevia Institutes top ten questions asked by our readers. Whether you are a physician working with patients interested in reducing calories and following a healthier lifestyle or a savvy consumer interested in understanding more about natural zero-calorie stevia, this question and answer session addresses the need-to-know facts about stevia and its use.
1. How is stevia produced?
The stevia extract production process uses conventional plant extraction methods. Stevia leaves are first dried and then steeped like tea. The plant extract is then filtered to separate the sweet steviol glycosides from the liquid and plant biomass. The stevia extract can then be further purified to an extract that contains one or more steviol glycosides through additional purification processes. The steviol glycosides remain intact as found in the stevia leaf throughout the entire process.
2. Why is stevia extracted and purified?
The water extraction process allows the sweet components of the stevia leaf, called steviol glycosides to be removed from the plant. Extracting and purifying stevias sweet components allows stevia producers to reduce off-flavor notes from other naturally occurring compounds in the plant and produce a cleaner tasting, more sugar-like stevia extract.
3. How are stevia ingredients found in foods and beverages today different from past stevia extracts?
Generally, stevia ingredients found in most food and beverage products today are high purity stevia extracts. High purity stevia extracts are specified as stevia extracts that have 95% or greater steviol glycoside content. High purity extracts have a cleaner, more sugar-like taste than stevia extracts found in the past and are approved for food and beverage use by the major regulatory authorities.
4. Where can I find stevia?
Stevia is now available for consumers in many ways. Sometimes it is the sole sweetener in a product, sometimes it is blended with other sweeteners. Often it is blended with sugar in reduced-calorie products. Stevia may be found in hundreds of items differing around the world, including stevia-sweetened teas, soft drinks, juices, yogurt, soymilk, granola and snack bars, and baked goods. Stevia can also be found in health snacks, cereal, salad dressings, alcoholic beverages, chewing gum, canned fruit and jam, confections and as a tabletop sweetener.
5. How are steviol glycosides metabolized by the body?
Largely responsible for stevias safety and non-caloric status is the fact that steviol glycosides are poorly absorbed in the body. Steviol glycosides are digested primarily by gut bacteria in the large intestines into steviol. Through a series of digestive processes steviol is broken down further into a compound called steviol glucuronide. The steviol glucuronide is then removed from the body in the urine. Research also shows that there is no accumulation of stevia (or any component or by-product of stevia) in the body and that it passes through the body nearly entirely. 1
6. Whats the difference between Reb A and stevia extract?
Stevia extract can contain one or more steviol glycosides, the sweet components of the stevia plant. Steviol glycosides naturally occur at different concentrations in the stevia plant. The glycosides share the same steviol molecular core, but differ in the number and arrangement of glucose molecules attached to the core. Due to this distinction, steviol glycosides can differ in taste and sweetness. Reb A (Rebaudioside A) is one of the sweetest and most abundant steviol glycosides found in the stevia leaf, and its commonly used to sweeten foods and beverages.
7. Does stevia have any functional benefits, i.e. side effects on the body such as reducing blood glucose or blood pressure?
The proven benefit of adding stevia to the diet is its ability to provide sweet taste with no calories. Over 200 studies, reviewed by major regulatory agencies including the Joint FAO/ WHO Expert Committee on Food Additives (JECFA) and European Food Safety Authority (EFSA) attest to stevia safety and its lack of side effects. More specifically, in a 2010 scientific evaluation, EFSA stated that stevia had no effect on blood glucose regulation (glucose homeostasis) or blood pressure in people with normal glucose tolerance and in people with type-2 diabetes when given single doses of 1000 mg steviol glycosides (97% Rebaudioside A) per person per day. Longer term studies also did not show any effect on glucose homeostasis or blood pressure. A 16-week study with repeated stevia use of 1000 mg rebaudioside A/person/day demonstrated no change in glucose homeostasis in people with type 2 diabetes. In a four week study with the same dosage, there were no significant changes in blood pressure in people with normal and low systolic blood pressure.1
8. Is stevia safe for pregnant women and children?
Yes. After reviewing numerous studies, major regulatory authorities including JECFA, EFSA, the US Food and Drug Administration (FDA), and Food Safety Australia and New Zealand (FSANZ) have determined that stevia is safe for the general population, including pregnant women and children when consumed within recommended levels.2 (See question on ADI for further information.)
9. Is stevia safe for people with diabetes?
Yes, stevia is safe for children and adults with diabetes. 1 Stevia is a naturally sourced sweetener with with zero calories, and it has no significant effect on blood glucose levels as it has no carbohydrates and zero effect on the glycemic index. The most important aspect to managing diabetes is controlling blood glucose levels, which can be achieved through managing carbohydrates in the diet and monitoring blood glucose. Stevia allows people with diabetes to enjoy the taste of sweet safely. Stevia is sometimes used with other natural sweeteners like sugar or in products that contain carbohydrates, so it is still important to check ingredient labels on foods and beverages.
10. Why does stevia have an Acceptable Daily Intake if it is safe?
The Joint Expert Committee on Food Additives (JECFA) defines an Acceptable Daily Intake value for food additives that are approved as safe for general use in food and beverages. The ADI serves as a margin of safety and is defined as the amount of a food additive, expressed on a bodyweight basis that can be ingested daily over a lifetime without appreciable health risk. JECFA has evaluated the safety of stevia and determined an Acceptable Daily Intake (ADI) expressed in steviol equivalents of 4 mg/kg/day over a lifetime. 2 This equates to approximately 12 mg of high purity stevia extracts per kg of body weight per day. The ADI was set by reviewing many research studies, including those demonstrating that daily doses of steviol glycosides up to 1,000 mg/person/day were well-tolerated by people with normal glucose metabolism and people with type-2 diabetes. Food and beverage manufacturers use the ADI to guide how they use stevia as in ingredient in products according to regulation.
References
Scientific Opinion on the safety of steviol glycosides for the proposed uses as a food additive European Food Safety Authority (EFSA) Panel on Food Additives and Nutrient Sources added to Food, (ANS) European Food Safety Authority (EFSA), Parma, Italy, 2010. (47) Safety Evaluation on Certain Food Additives Prepared by the 69th Meeting of the Joint FAO/ WHO Expert Committee on Food Additives (JECFA), 2.2.5 Reproductive toxicity
