Many of the commercial stevia blends contain very little of the actual stevia plant. Sometimes they have been altered so they contain chemical solvents.
Stevia's glycosides is the component in the plant that is responsible for it's sweetness. Specifically they are: stevioside, rebaudioside (which have 5 variations: A, B, C, D, E & F), steviolbioside & isosteviol. These active compounds, mainly the stevioside & the rebaudioside, contain 30-150 times the sweetness of sugar. They are heat stable, pH stable, but not fermentable. The body doesn't metabolize the glycosides so it contains zero calories.
Now stevioside is sweet, but has a bitter licorice aftertaste. The rebaudiosides are sweet with no bitterness & are usually present in highly refined commercial stevia products. When companies make their version of the sweetner, the plant is subjected to a water extraction process. During this process, it loses about 50% of the rebaudioside A. They separate the various glycosides & are then purified via a crystallization technique using ethanol or methanol as a solvent. Yummm, sounds like something I want to put into my body regularly...not!! So stevia extracts & derivatives are produced industrially & marketed under different trade names.
It's also a good source of polyphenols, carotenoids, chlorophyll compounds & amino acids making the whole plant the optimum choice to add to your diet instead of processed down sugar & toxic sweetners.
It's interesting that the only part of stevia that's been approved by the FDA is the highly processed powder form of stevia. Which is chemically processed, contains genetically modified ingredients (GMO's) & often only contains minute traces of actual stevia!!!
Recent studies have found that stevia has the potential to terminate chronic lyme disease which a 2-4 week round of antibiotics sometimes can & sometimes can't defeat this tricky bacteria. Stevia leaf extract is rich in many phytonutrients that are known antimicrobial agents to help get rid of most persistent forms of lyme disease. This study even found how the extract could help lower high blood pressure & reduce blood glucose in type II diabetics, help in weight loss & contains anticancer properties.
A pinch of stevia powder is = to about 1 tsp. of sugar. Do not use if pregnant, especially if it's the commercial type.
Sources: thetruthaboutcancer.com, healthline.com, Wikipedia.com, DrAxe.com & RenegadeTribune.com