History and Research
The stevia plant is native to South America, where the people of Paraguay and Brazil have been using it for centuries to sweeten the traditional yerba mate drink and to treat a whole host of ailments. The name stevia actually denotes a rather large genus of plants, although in common language stevia generally refers to the stevia rebaudiana plant. Dr. Moises Bertoni is credited with “discovering” this plant in 1887 and was astounded to find that it is 250-300 times sweeter than sucrose (table sugar). Stevia crossed the radar of science in the early 20th century as a sweeter (and cheaper) alternative to table sugar. Due to health concerns over other artificial sweeteners, the Japanese scientific community, and later the food industry, turned to stevia to sweeten everything from soft drinks, to candy, pastry and began using it as a table sweetener. It has been used extensively in Japan and other parts of the world since the 1970s with no reported side effects or health concerns with much research to support its safety. North America, however, was much slower to adopt stevia because there was already a very competitive industry for artificial sweeteners, and as a natural substance, stevia was difficult to patent. When the glycosides (the active chemically “sweet” components of the plant) stevioside and rebaudioside were isolated, the North American Food and Drug Industry began to look much closer at this healthier alternative and research began. Even today, there is much debate about whether stevia should be marketed as a “dietary supplement” or a “food additive” - an important difference if it is to be further adapted into mainstream products.
Stevia has garnered attention in later years because it is a cost-effective sweetener that does not raise blood- pressure or blood-glucose levels — interesting implications for a society burdened by such chronic diseases as hypertension and diabetes. This natural sweetener is considered non-caloric because when it is metabolized in the GI tract, the stevioside and rebaudioside are converted to steviol, which is only minimally absorbed while the majority is eliminated in the feces. Although clinical research is somewhat conflicting, it appears that stevioside may act directly on the insulin-secreting beta cells of the pancreas. At the same time, insulin sensitivity may be improved (as well as more being secreted) and more glucose mobilized to be available for use by skeletal muscles. Thus, there is potential for stevia to encourage the body to process and handle glucose more effectively, without adding an increased burden of glucose. To that effect, an extract of stevia leaf actually increased glucose tolerance and reduced plasma glucose levels in a small study involving healthy volunteers with normal blood glucose levels — although whether these same effects apply to diabetics is yet to be conclusively confirmed. Studies are conflicting in terms of lowering blood pressure as well: some human and animal studies note that blood pressure can be reduced while others involving hypertensive patients failed to find a statistically significant difference. The basis for its effectiveness (sometimes) may be that in some animal studies, it was found that stevia can act as a vasodilator and diuretic — thus when the blood vessels are dilated and excess fluid is excreted, hypertension becomes less pronounced. In contrast, it is interesting to note that other studies, again, notice the most significant reduction in hypertension and blood-glucose levels while taking stevia when these parameters are elevated beyond the normal — more so than when they are within the normal range. Thus, it is difficult to say conclusively that stevia does or does not always reduce elevated levels (of blood-glucose or blood-pressure, for example) and if so, by how much and for whom — but more often than not there is some change. Stevia may also be a mild anti-bacterial: in vitro studies, stevia actually acted as a bactericide to many food-borne pathogens studied (including E.coli). In the GI tract, it also has the potential to ward off human colon carcinoma cells. Although some early studies from the 1980s showed some constituents of stevia to be potentially mutagenic, it was later found that the methodology used in these trials to be faulty and not reproducible. Centuries of use and worldwide commercial use today speak more to the safety of this natural substance than one flawed clinical study. At any rate, stevia is a natural calorie-free alternative to the blood-sugar spiking, cholesterol-elevating high-fructose corn syrup, and carcinogenic artificial sweeteners.
Dried stevia leaves can be ground and used as a sweetener, or soaked in water and the liquid used in baking or in preserves. A pinch of the leaf is enough to sweeten tea, or a little more may be added to many dishes or sprinkled onto food. The powdered extract is very concentrated so only a small amount is needed. For example, the amount that fits onto the tip of a toothpick is often said to be enough to sweeten tea or coffee. If you plan to use stevia in baking, a general guideline is that 1/4 tsp. of the powdered extract or 2 tbsp. of the dried leaf is equivalent to 1 cup of granulated sugar. Stevia is also heat stable (unlike other artificial sweeteners) so it can be incorporated safely — but remember to adjust ingredient ratios for the sweetness!
Research compiled and summarized by Keila McCullough, BHSc, ND (cand.)
For educational purposes only. This information has not been evaluated by the Canadian Food & Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.