In 2021 the European Food Safety Authority (EFSA) reviewed a new class of steviol glycoside sweeteners produced by enzymatic bioconversion of highly purified stevioside and/or rebaudioside A extracts. The opinion — published in the EFSA Journal — specifically considered enzyme‑modified preparations that enrich minor glycosides such as rebaudioside AM, and assessed identity, composition, production methods, analytical purity, metabolism and toxicology data to determine whether these preparations raise any safety concerns when used as food additives.
What EFSA evaluated
EFSA’s review covered the full chain of evidence available for the enzyme‑modified preparations: the composition and identity of the finished preparations, the enzymatic production process (which uses UDP‑glucosyltransferases and sucrose‑synthase enzymes expressed in non‑pathogenic E. coli K‑12 strains), analytical purity and specifications, in vitro and in vivo toxicology including genotoxicity testing, metabolism studies (including fecal incubation work), and available human data. The Panel also asked whether the existing acceptable daily intake (ADI) for steviol glycosides should still apply to these enzyme‑modified products.
The headline conclusions
EFSA concluded that there is no safety concern for the enzyme‑modified steviol glycoside preparations evaluated — including rebaudioside AM — provided they are produced to the compositional and purity specifications considered in the opinion. The panel reaffirmed that the existing ADI for steviol glycosides, 0–4 mg/kg body weight per day (expressed as steviol equivalents), remains the applicable safety benchmark. For context, the upper end of that ADI corresponds to about 280 mg steviol equivalents per day for a 70 kg adult (4 mg × 70 kg = 280 mg).
Why EFSA reached that view
Key points behind the conclusion were that the evaluated steviol glycosides are metabolised by intestinal/colonic microbiota to steviol, which is then absorbed and converted to steviol glucuronide for excretion — the same metabolic pathway considered in earlier assessments. Toxicology and genotoxicity data available for the preparations did not identify genotoxic or carcinogenic risks at exposure levels relevant to human consumption under the evaluated specifications. The Panel also judged the enzymatic production method acceptable so long as manufacturing controls ensure the absence of residual production organisms, DNA or enzyme proteins in the final product at levels of concern.
Important limitations and consumer takeaways
EFSA’s opinion is specifically tied to the preparations and manufacturing methods it reviewed. The safety conclusions apply to products that meet the described compositional and purity specifications (commonly framed around high total steviol glycoside content — for example, specification frameworks often reference ≥95% total steviol glycosides). The opinion does not assess clinical benefits (for example effects on blood sugar or weight) and is not based on extensive long‑term human trial data — it is principally a toxicological and metabolic safety assessment. It also does not endorse products that differ in composition, purity or manufacturing controls from those explicitly assessed.
Practical advice
For consumers and writers: the 2021 EFSA opinion is reassuring about the safety of these enzyme‑modified steviol glycosides when produced to the evaluated specifications, and it confirms the continued use of the 0–4 mg/kg body weight ADI as the regulatory safety reference. If you choose stevia‑derived sweeteners, prefer products from reputable manufacturers that comply with regulatory specifications and labeling, and remember that this EFSA opinion addresses safety (risk of toxicity) not clinical efficacy or health benefits.
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