Research studies on the safety and effect of stevia:
The safety of steviol glycosides has been extensively studied and reported in the scientific literature. In humans, steviol glycosides are not hydrolyzed by digestive enzymes of the upper gastrointestinal tract and are not absorbed through the upper portion of the gastrointestinal tract. Several chronic studies and clinical studies in humans have been conducted demonstrating no adverse effects.
Below are few articles on the safety of Rebaudiosides (sweetest components of the stevia leaf):
‘Sweeter’ than its name: anti-inflammatory activities of Stevia rebaudiana (PDF)
Steviol Represses Glucose Metabolism and Translation Initiation in Pancreatic Cancer Cells
Antioxidant, anti-diabetic and renal protective properties of Stevia rebaudiana.
Effect of Rebaudioside A, a diterpenoid on glucose homeostasis in STZ-induced diabetic rats.
Anti-Cancer Properties of Stevia rebaudiana; More than a Sweetener
Stevia (Stevia rebaudiana) Improves Carotenoid Content in Eggs When Fed to Laying Hens
The Effects of Stevia Consumption on Gut Bacteria: Friend or Foe?
Safety evaluation of glucosylated steviol glycosides as a food additive in different food categories
The Effect of Steviol Glycosides on Sensory Properties and Acceptability of Ice Cream