What is calcium silicate clay, and why is this ancient mineral receiving renewed scientific attention today? Modern food, water, and air carry low-level contaminants that the body must process every single day. In this article, I will explain what calcium silicate clay is, how it works inside the gut, and what current research published on PubMed and in peer-reviewed journals has actually measured. You will also learn why I chose to include calcium silicate clay as a key ingredient in Daily Brain Care.
What Is Calcium Silicate Clay (and Where It Comes From)?
Calcium silicate clay is a naturally-occurring smectite mineral formed from weathered volcanic ash, with calcium montmorillonite clay as its most-studied subtype (Ng et al., 2025). Its layered silicate sheets carry a strong negative surface charge, which gives the clay an unusually high capacity to attract and hold positively charged molecules inside the gut.
Traditional cultures across Africa, the Mediterranean, and the Americas have eaten purified clay for centuries (Ng et al., 2025). Modern food-grade calcium silicate clay, sometimes labeled NovaSil or ACCS100 in the literature, is purified, milled, and tested to meet strict human consumption standards. Throughout this article, calcium silicate clay refers specifically to this food-grade calcium montmorillonite clay, not the construction material made from lime and sand.
How Calcium Silicate Clay Works in the Body
Calcium silicate clay is not absorbed into the bloodstream. It acts locally inside the gastrointestinal tract and is excreted in the stool (Ng et al., 2025). Its layered structure offers an enormous surface area packed with exchangeable calcium ions, which trade places with certain metals and other positively charged compounds. Once a compound binds to the clay, it stays bound during digestion and exits the body, which is the mechanism investigators have measured (Pollock et al., 2016). This binding behavior is why scientists describe calcium silicate clay as a selective enterosorbent (i.e., a substance that binds material within the gut) rather than a drug. The gut is also a signaling organ, not merely a passage. I explain that traffic in my article on the gut brain connection.
What Researchers Have Measured About Smectite Clays
I want to describe this literature precisely, because much of it was conducted with clinical preparations in patient populations rather than with a dietary supplement in healthy adults.
Researchers have studied smectite clays in children with acute diarrhea, pooling nine randomized controlled trials and measuring symptom duration against placebo (Szajewska et al., 2006). That work examined a clinical preparation in a pediatric population, and it is not a statement about what a dietary supplement does. Investigators have also studied oral montmorillonite in children with abdominal Henoch–Schönlein purpura, measuring markers of intestinal mucosal barrier function (Gao et al., 2018). I cite it because it describes the barrier mechanism, and for no other reason. I think of the clay as a quiet housekeeper inside the gut, gathering what should not be there and escorting it gently out of the body.
Calcium Silicate Clay as a Mycotoxin Binder
Mold-produced mycotoxins, particularly aflatoxin B1, are common low-level contaminants of corn, peanuts, and grains, and reducing dietary exposure to them is a reasonable goal on its own terms.
In a randomized double-blind trial in 234 adults in South Texas, three months of calcium montmorillonite clay reduced serum aflatoxin biomarkers without disturbing vitamin or mineral status (Pollock et al., 2016). A separate double-blind crossover trial in Kenyan adults showed that 3 grams per day of refined clay reduced urinary aflatoxin biomarkers and was well tolerated (Awuor et al., 2017). I want to be straightforward about dose. Those trials used roughly 1.5 to 3 grams of clay per day as a standalone intervention, which is a larger amount than the clay contributes within a multi-ingredient daily formula. Their findings describe what that intervention measured, and they do not transfer automatically to a different amount in a different product. In laboratory testing, acid-processed montmorillonite tightly bound arsenic, cadmium, mercury, and lead in solution, supporting its role as a heavy-metal sorbent in vitro (Wang et al., 2021).
I set out the wider picture of what heavy metals are and where everyday exposure comes from in a separate article. Inside the same formula, calcium silicate clay works alongside inositol hexaphosphate (IP6), another naturally occurring molecule with mineral-binding activity. You can read more about the thinking behind my formulas on the Dr Lewis Nutrition About page.
Safety and How I Use Calcium Silicate Clay in Daily Brain Care
In a controlled human safety trial in healthy adults, NovaSil calcium montmorillonite clay produced no adverse changes in liver enzymes, kidney function, or blood counts (Wang et al., 2005). Longer intervention trials in Ghana and Texas have likewise reported no clinically meaningful changes in serum vitamins A or E or in trace minerals (Pollock et al., 2016). Quality matters. Pharmaceutical-grade calcium silicate clay is purified to remove naturally occurring trace metals, and its bioavailable lead and arsenic remain extremely low (Ng et al., 2025).
I source the calcium silicate clay used in Daily Brain Care from a verified food-grade supplier and require each batch to be tested for purity and metal content. Always pair clay-based supplements with adequate water, take them away from medications, and speak with your physician before starting, particularly if you take prescription drugs or are pregnant or nursing.
Conclusion
Now you know what calcium silicate clay is, how it works in the gut, and what the published science has actually measured. It is a naturally occurring smectite mineral studied as a gentle, non-absorbed binder, with a body of human safety data behind it. If you want this ancient mineral plus other research-supported ingredients, such as citric acid, in one daily formula, take a look at Daily Brain Care today.
Frequently Asked Questions
What is calcium silicate clay used for?
Calcium silicate clay is used as a non-absorbed gut binder. Researchers have studied it for its capacity to bind mycotoxins and metals within the gastrointestinal tract and to support the body’s normal elimination pathways.
Is calcium silicate clay safe to take daily?
Human clinical trials lasting up to three months at doses up to 3 grams per day have reported no adverse changes in liver, kidney, or blood markers in healthy adults (Wang et al., 2005; Pollock et al., 2016). Speak with your physician before starting any supplement.
What is the difference between calcium silicate clay and bentonite clay?
Both are smectite clays. Calcium silicate clay (i.e., calcium montmorillonite) carries calcium as its primary exchangeable ion, while bentonite usually refers to the sodium-rich form. The calcium form is the more extensively studied food-grade variety.
How does calcium silicate clay work in the gut?
It is not absorbed. It stays in the gastrointestinal tract, where its negatively charged layered structure binds positively charged compounds and carries them out through the stool (Ng et al., 2025).
References
Awuor, A. O., Yard, E., Daniel, J. H., Martin, C., Bii, C., Romoser, A., Oyugi, E., Elmore, S., Amwayi, S., Vulule, J., Zitomer, N. C., Rybak, M. E., Phillips, T. D., Montgomery, J. M., & Lewis, L. S. (2017). Evaluation of the efficacy, acceptability and palatability of calcium montmorillonite clay used to reduce aflatoxin B1 dietary exposure in a crossover study in Kenya. Food Additives & Contaminants: Part A, 34(1), 93–102. https://doi.org/10.1080/19440049.2016.1224933
Gao, X., Miao, R., Tao, Y., Chen, X., Wan, C., & Jia, R. (2018). Effect of montmorillonite powder on intestinal mucosal barrier in children with abdominal Henoch–Schönlein purpura: A randomized controlled study. Medicine, 97(39), e12577. https://doi.org/10.1097/MD.0000000000012577
Ng, M. K., Jacofsky, D. J., Barsoum, W. K., & Mont, M. A. (2025). Human health applications of calcium montmorillonite clay: A systems-based review. Cureus, 17(10), e95449. https://doi.org/10.7759/cureus.95449
Pollock, B. H., Elmore, S., Romoser, A., Tang, L., Kang, M. S., Xue, K., Rodriguez, M., Dierschke, N. A., Hayes, H. G., Hansen, H. A., Guerra, F., Wang, J.-S., & Phillips, T. D. (2016). Intervention trial with calcium montmorillonite clay in a south Texas population exposed to aflatoxin. Food Additives & Contaminants: Part A, 33(8), 1346–1354. https://doi.org/10.1080/19440049.2016.1198498
Szajewska, H., Dziechciarz, P., & Mrukowicz, J. (2006). Meta-analysis: Smectite in the treatment of acute infectious diarrhoea in children. Alimentary Pharmacology & Therapeutics, 23(2), 217–227. https://doi.org/10.1111/j.1365-2036.2006.02760.x
Wang, M., Bera, G., Mitra, K., Wade, T. L., Knap, A. H., & Phillips, T. D. (2021). Tight sorption of arsenic, cadmium, mercury, and lead by edible activated carbon and acid-processed montmorillonite clay. Environmental Science and Pollution Research, 28(6), 6758–6770. https://doi.org/10.1007/s11356-020-10973-z
Wang, P., Afriyie-Gyawu, E., Tang, Y., Johnson, N. M., Xu, L., Tang, L., Huebner, H. J., Ankrah, N.-A., Ofori-Adjei, D., Ellis, W., Jolly, P. E., Williams, J. H., Wang, J.-S., & Phillips, T. D. (2005). Short-term safety evaluation of processed calcium montmorillonite clay (NovaSil) in humans. Food Additives & Contaminants, 22(3), 270–279. https://doi.org/10.1080/02652030500111129
