WHO FOOD ADDITIVES
Safety evaluation of certain food additives
Prepared by the Sixty-third meeting of the Joint FAO/WHO
Expert Committee on Food Additives (JECFA)
Geneva, 2006 6
Extract, point 4 and 5 of 28 pages:
Download complete evaluation on Stevia
After oral administration, steviol glycosides are poorly absorbed in experimental animals and in humans.
Intestinal microflora metabolize steviol glycosides to the aglycone, steviol, by successive hydrolytic removal of glucose units. Data reviewed by the Committee at its current and fifty-first meetings (Annex 1, reference 149) indicated that this process is similar in rats and humans. The hydrolysis of rebaudioside A to steviol was slower than that of stevioside. In humans treated orally with stevioside, small amounts of steviol were detected in the plasma, with considerable interindividual variability. The major route by which steviol is metabolized in humans in vivo appears to be via conjugation with glucuronide and/or sulfate. Studies with liver microsomal preparations indicated that steviol is also metabolized to a number of hydroxy and dihydroxy derivatives via CYP-dependent pathways.
Stevioside and/or steviol affected a variety of biochemical parameters in models in vitro, indicating possible mechanisms of antihypertensive and antiglycaemic effects that involve modulation of ion channels. High concentrations (e.g. 1 mmol/l) of stevioside were required to produce a maximal increase in insulin secretion, while steviol was effective at a concentration that was about three orders of magnitude lower. Stevioside also affected a variety of biochemical parameters in different animal species in vivo, mostly with parenteral administration; these studies were considered by the Committee to be of limited relevance to dietary exposure.