How much steviol will be taken up by the colon?
If all of the added sugar (131 g/day) is substituted for by stevioside, which is nearly impossible, then about 400 mg stevioside is required per day. Degradation in the colon gives about 160 mg steviol. About 90 % of the steviol formed is excreted with the faeces. Small amounts of steviol are taken up by the colon and conjugated to be excreted in the urine. In hamsters fed 250 mg steviol/kg body weight, a free steviol concentration of about 102 µg/ml plasma was without harmful effects. In humans no free steviol could be detected in plasma after oral administration of 750 mg stevioside per person per day (± 12 mg/kg bw). The maximal peak concentration of conjugated steviol was around 20 µg/ml, i.e. far below the values found safe for hamsters. As less than 400 mg stevioside will be used per day, this value will be rather below 10 µg/ml. The conjugated steviol derivatives are excreted into the urine.
