Is silica safe as a food additive (E 551)?

Synthetic amorphous silica (SAS) is designated as a food additive in the EU by ID number E 551. The effects of SAS on humans, animals, and the environment have been tested extensively. Only very small concentrations of SAS are used in food, and no adverse health effects of any kind have been identified to date. Consumption of even relatively large quantities is harmless.
In addition, the European Food Safety Authority regularly reviews E 551, which is approved for use as an additive in the EU. The most recent evaluation was made public in January 2018, confirming that no indications of toxicity have been found and that E 551 may continue to be used safely as a food additive. This approval, as is the case for all substances with “E” designations, serves as official reassurance to all consumers that the additive is safe and may be used with no concerns.

Synthetic amorphous silica (SAS) meeting the specifications in Regulation (EU) No. 231/2012 has been approved for use in the European Union (EU) as food additive E 551 and is regularly reviewed by the European Food Safety Authority (EFSA) with regard to its safety. The most recent assessment was made public in January 20181:
- All of the studies used for this assessment found that E 551 has no toxicologically relevant effects.
- The highest dose tested at which no toxicological effects were found is significantly higher than the estimated exposure level of a normal consumer.
- The EFSA recommends continued data collection - a chronic toxicity study in particular—in order to define the acceptable daily intake (ADI).
- The EFSA further recommends updating E 551 specifications with respect to heavy metal thresholds and particle size distribution.
To summarize, the EFSA reevaluation has confirmed the safety of E 551 as a food additive.
The form in which SAS is added to food DOES NOT correspond to the current recommended definition of nanomaterials given in Regulation (EU) No. 1169/2011 (the provision of food information to consumers) or in Regulation (EU) No. 2283/2015 (novel foods). As such, the term “nanosilica” should not be used in conjunction with the use of SAS as a food additive.
E 551 has been studied more intensively than most other substances, and no adverse health effects have been demonstrated to date, either in cell cultures or in animals, even at extremely high doses beyond what could normally be consumed in food. A recently published Dutch study (Van der Zande et al., Particle & Fibre Tox. (2014)) reported indications of potential fibrotic changes in the livers of rats that had been repeatedly force-fed SAS over a period of 3 months. The work described in this paper was not conducted according to OECD guidelines and contained glaring flaws. No reliable effects could be determined when this study was reevaluated. This is in agreement with the overall findings of Professor Harald Krug, a renowned expert on nanotoxicology who has conducted a comprehensive assessment of the relevant literature over the past ten to twenty years: “Most studies allow for no clear conclusions on the safety of nanomaterials. On the contrary, most papers are contradictory or come to utterly false conclusions.” (Fruijtier-Pӧlloth, Arch Toxicol. (2016))
None of the studies conducted according to current guidelines have demonstrated damaging health effects of any kind caused by SAS to the liver or other organ systems, including the nervous and immune systems. Compliance with the latest guidelines is extremely important, as it is the only way to prevent problems such as overdosing and measurement errors. It is also the only way to assure that different studies will be comparable.