Silicon Dioxide vs Calcium Propionate: which is worse?

What is Silicon Dioxide?

Silicon dioxide (silica) is a naturally occurring mineral compound used as an anti-caking agent in powdered and granular foods. The food-grade form is amorphous (non-crystalline) synthetic silica, distinct from the crystalline quartz form associated with lung disease. It absorbs moisture and prevents clumping in powders.

What is Calcium Propionate?

Calcium propionate is the calcium salt of propionic acid, a short-chain fatty acid naturally produced during fermentation. It is one of the most widely used mold inhibitors in commercial bread and baked goods. It works by penetrating fungal cells and lowering internal pH to inhibit growth.

Documented risks

Silicon Dioxide: Food-grade amorphous silicon dioxide is generally recognized as safe. EFSA re-evaluated it in 2018 and concluded there was no safety concern at typical dietary exposure levels; however, the panel noted uncertainty about nanoparticle forms. The food form should not be confused with crystalline silica (quartz) dust, which is a recognized carcinogen when inhaled occupationally. Ingested amorphous silica passes through the body largely unabsorbed.

Calcium Propionate: Generally recognized as safe. However, a 2012 study in the Journal of Pediatric Child Health (Dengate & Ruben) and a 2019 study published in Science Translational Medicine found that calcium propionate induced insulin resistance in a mouse model and raised metabolic concerns. The 2019 animal study, conducted by Bhatt et al., found that propionate triggered glucagon and norepinephrine secretion. Some open-label human studies and parental reports have linked calcium propionate to irritability, sleep disturbance, and behavioral changes in sensitive children, though these lack robust clinical trial evidence. Most regulatory agencies consider it safe at current use levels.