Calcium silicate clay is a natural mineral that researchers have studied for one narrow job, which is binding unwanted compounds inside the gut. Most people meet the name on a supplement label and have no idea whether it is an ingredient, a filler, or something to avoid. This article explains what calcium silicate clay is and how it differs from the anticaking agent with a similar name. I also cover what studies have measured, where that research stops, and why I chose calcium silicate clay for 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, and calcium montmorillonite is its most studied form (Ng et al., 2025). Its layered silicate sheets carry a strong negative surface charge. That charge gives the clay an unusually high capacity to attract and hold positively charged molecules.
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, labeled NovaSil or ACCS100 in some of the literature, is purified and milled for human consumption. Throughout this article, calcium silicate clay means this food-grade calcium montmorillonite, not the construction material made from lime and sand. The calcium in calcium silicate clay names its exchangeable ion, and I cover how the body routes dietary calcium in vitamin D3 and K2.
Why Is Calcium Silicate in My Supplement?
Many readers reach this article after spotting calcium silicate on a supplement label and wondering why it is there. The answer depends on which of two different materials the label means. One is a manufactured flow agent, and the other is the natural clay this article describes.
Synthetic calcium silicate is a fine white powder that manufacturers add in small amounts to keep powders from clumping. U.S. food regulations list calcium silicate as an anticaking agent, permitted at no more than 2 percent of a food by weight (21 CFR 172.410). A second rule caps it at 2 percent in table salt and 5 percent in baking powder (21 CFR 182.2227).
The calcium silicate clay in Daily Brain Care is the other material, the natural calcium montmorillonite described in the section above. It is part of the formula as an ingredient, not a flow agent added to keep the powder moving. A label that says clay or montmorillonite points to the mineral, and a manufacturer should be able to tell you which one a product contains.
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 leaves the body in the stool (Ng et al., 2025). Its layered structure offers a large surface area lined with exchangeable calcium ions, which trade places with certain metals and other positively charged compounds.
Once a compound binds to the clay, it tends to stay bound through digestion and leave the body with it (Ng et al., 2025). In laboratory solutions, acid-processed montmorillonite tightly bound arsenic, cadmium, mercury, and lead (Wang et al., 2021). That finding came from a test tube, not a digestive tract, and it describes the chemistry rather than an effect in people.
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 for food. I explain that traffic in my article on the gut brain connection.
What Researchers Have Measured About Smectite Clays
Much of this literature used clinical preparations in patient populations rather than a dietary supplement in healthy adults. That distinction governs how far any of it travels. I report each study by the population it enrolled for that reason.
A meta-analysis pooled nine randomized controlled trials of smectite clays in children with acute diarrhea and measured symptom duration against placebo (Szajewska et al., 2006). That work examined a clinical preparation in a pediatric population, and it says nothing about what a dietary supplement does. In children with abdominal Henoch–Schönlein purpura, investigators measured markers of intestinal barrier function after oral montmorillonite (Gao et al., 2018). I cite it only because it describes the barrier mechanism.
Calcium Silicate Clay as a Mycotoxin Binder
Mold-produced mycotoxins, particularly aflatoxin B1, are common low-level contaminants of corn, peanuts, and grains. Reducing dietary exposure to them is a reasonable goal on its own terms. The best human evidence for calcium montmorillonite clay concerns exactly this question.
In a randomized double-blind trial in 234 adults in South Texas, three months of calcium montmorillonite clay reduced serum aflatoxin biomarkers (Pollock et al., 2016). In a double-blind crossover trial in Kenyan adults, 3 grams a day of refined clay reduced urinary aflatoxin biomarkers (Awuor et al., 2017). Both trials measured exposure markers in populations with known dietary aflatoxin, not outcomes in the average American eater.
Dose deserves a plain statement. Those trials gave roughly 1.5 to 3 grams of clay a day as a standalone intervention. That is more 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. I set out the wider picture of what heavy metals are and where everyday exposure comes from in a separate article.
Is Calcium Silicate Clay Bad for You? What Human Trials Measured
The human trials behind this question were short, used specific clay preparations, and enrolled limited populations. Those limits come first, since no study of a few months settles every question about daily use. With that said, investigators did measure the markers a careful reader would want checked.
In a short-term trial of NovaSil in healthy adults, investigators measured liver enzymes, kidney function, and blood counts and reported no adverse changes (Wang et al., 2005). The South Texas investigators also measured serum vitamins A and E and trace minerals and reported no clinically meaningful changes in those adults (Pollock et al., 2016). Those results describe those preparations and doses, not a promise about any product, including mine.
Natural clays can carry trace metals, which is why food-grade clay is purified before use (Ng et al., 2025). Each production lot of Daily Brain Care goes through testing for lead, arsenic, mercury, and cadmium. Batch testing matters across every supplement category, and an analysis of commercial products measured against their labels appears in vitamin K2 MK-7.
Take any clay-based supplement with adequate water and apart from medications, since a binder in the gut is best kept apart from them. Speak with your physician before starting, particularly if you take prescription drugs or are pregnant or nursing. A short conversation beforehand costs you nothing.
What Is Calcium Silicate Clay Good For? How I Use It in Daily Brain Care
I included calcium silicate clay in Daily Brain Care as a gut-level binder, the role its human trials measured. I take the formula myself every day, alongside the whole-food, plant-based diet I have eaten since 1999. My own diet leans on grains and legumes, which are exactly the foods where mold contaminants tend to appear.
The clay is one ingredient in a proprietary blend, so the amount per serving is not printed on the label. I explain what that trade costs a buyer in what a proprietary blend is. The formula also contains inositol hexaphosphate, whose chemistry I cover in inositol hexaphosphate (IP6).
I would rather state these limits myself than leave them for you to discover. The trials above support a narrow, specific use, and I describe the clay no more broadly than that. You can read more about how I approach every formula on the Dr Lewis Nutrition About page.
Conclusion
What is calcium silicate clay, in short? It is a natural montmorillonite mineral that stays in the gut, where researchers have studied it as a binder. Its clearest human evidence comes from short trials on aflatoxin exposure markers, and its metal binding comes from laboratory solutions. It is also a different material from the synthetic calcium silicate that keeps powders flowing. If you want this clay alongside other research-grounded ingredients, such as citric acid, in one daily formula, add Daily Brain Care to your routine today.
Frequently Asked Questions
What is calcium silicate clay?
Calcium silicate clay is a food-grade calcium montmorillonite, a natural smectite mineral formed from weathered volcanic ash. It stays in the gut, where researchers have studied it as a binder (Ng et al., 2025).
What is calcium silicate clay used for?
Researchers have studied calcium silicate clay as a non-absorbed binder in the gut. Human trials measured its effect on aflatoxin exposure markers in adults in South Texas and Kenya (Pollock et al., 2016; Awuor et al., 2017).
Why is calcium silicate in my supplement?
Most often, synthetic calcium silicate is an anticaking agent that keeps powders flowing, permitted in food at no more than 2 percent by weight (21 CFR 172.410). Calcium silicate clay is a different material, a natural montmorillonite included in some formulas as an ingredient.
Is calcium silicate clay bad for you?
Short-term trials in adults measured liver, kidney, blood, vitamin, and mineral markers and reported no adverse changes (Wang et al., 2005; Pollock et al., 2016). Those trials were brief and used specific preparations. Take clay apart from medications, and ask your physician first if you take prescription drugs or are pregnant or nursing.
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
Calcium silicate, 21 C.F.R. § 172.410 (2026). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172/subpart-E/section-172.410
Calcium silicate, 21 C.F.R. § 182.2227 (2026). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-182/subpart-C/section-182.2227
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
