Following a request from the European Commission, the European Food Safety Authority (EFSA) Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion regarding the safety of an amendment of the specifications for the food additive steviol glycosides (E 960).
The current specifications laid down in Commission Regulation (EU) No 231/2012 stipulate that steviol glycosides (E 960) preparations contain not less than 95% of the 10 named steviol glycosides: stevioside; rebaudiosides A, B, C, D, E and F; steviolbioside; rubusoside and dulcoside, on a dried basis. The specifications further define the preparations as comprising mainly (i.e. at least 75%) of stevioside and/or rebaudioside A. Although available commercial preparations of stevia extracts have been shown to contain measurable levels of rebaudioside M, rebaudioside M is presently not listed as one of the steviol glycosides that may be included with other steviol glycosides to make up the set assay limit of at least 95% total steviol glycosides.
The use of steviol glycosides (E 960) as a food sweetener is regulated under the European Parliament and Council Regulation (EC) No 1333/2008 on food additives. Several assessments were made for stevioside as a sweetener by the Scientific Committee for Food (SCF in 1984-1999), the Joint FAO/WHO Expert Committee on Food Additives (JECFA in 2000-2010 time frame) and EFSA (2010-2015). JECFA and EFSA have established an Acceptable Daily Intake (ADI) for steviol glycosides (E 960) of 4 mg/kg bw (body weight) per day, expressed as steviol equivalents. Refined exposure assessments for extension of use in 2011–2015 period were also performed by EFSA.
According to the applicant, steviol glycoside preparations may contain rebaudioside M at a range of concentrations, from 50% up to nearly 100%. While extracts characterised by a ≥95% content of rebaudioside M contain <5% of rebaudiosides D, A and B combined, extracts with a lower rebaudioside M content (approximately 50%) may comprise close to 40% rebaudioside D and 7% rebaudioside A. Studies regarding the stability of rebaudioside M under normal and exaggerated storage condition as well as a forced degradation studies were also provided by the applicant.
As rebaudioside M-rich steviol glycoside products are proposed for the same uses and use levels than previously evaluated steviol glycosides, the expected resulting exposure will be no greater than the one estimated in the last assessment made by EFSA.
The Panel considers that the critical step in the assessment of rebaudioside M by read across was an evaluation of its metabolism and a comparison with the metabolism of rebaudioside A and stevioside that are the steviol glycosides covered by the current specification. For rebaudioside A and stevioside there was an essentially complete degradation to steviol in the gastrointestinal tract at realistic doses, the steviol produced was absorbed and then metabolised to steviol glucuronide. The Panel considers that the steviol exposure from an equivalent dose of rebaudioside D and M can be estimated and that considering the common degradation steps their safety could be evaluated on the same basis as stevioside and rebaudioside A. An evaluation of the glycosidic substitutions at the R1 and R2 position in the structure were also taken into consideration in extrapolating the available data for other steviol glycosides. A series of in vitro metabolism studies were conducted to assess individual steviol glycosides at concentrations of 0.2 and 2 mg/mL for up to 48 hours and by looking at the rate and degree of microbial hydrolysis. The Panel has also requested additional data to confirm the plausibility of this hypothesis.
Based on the structure–activity relationships observed with rebaudiosides A, D and M and the in vitro results, the Panel considered that it was plausible that the metabolism of rebaudioside M to steviol would be no greater than that observed with rebaudioside D and that a significant amount of intact rebaudioside M was unlikely to be absorbed. There is a consistent picture of high break down by the microflora in vitro of steviosides, rebaudiosides and dulcosides with production of steviol which is subsequently absorbed, metabolised and eliminated, the only systemic exposure being to steviol and, as previously concluded, toxicological studies on steviol are considered relevant to the assessment of these compounds.
From pooling all the evidence the ANS Panel concluded that extending the current specifications to include rebaudiosides D and M as alternatives to rebaudioside A in the predominant components of steviol glycosides would not be of safety concern.
The Panel also concluded that provided that the total amount of steviol glycosides (stevioside; rebaudiosides A, B, C, D, E, F and M; steviolbioside; rubusoside and dulcoside) were greater than 95% which are all converted to steviol and given that there was no evidence of absorption for intact glycosides at realistic use levels, the specific steviol glycosides (E 960) composition would not be of safety concern.
Finally the Panel concluded that the ADI of 4 mg/kg bw/day can also be applied where total steviol glycosides comprise more than 95% of the material.