A recent investigation by CWC Labs, an independent laboratory founded by food scientist Mike Adams, has uncovered that nearly all major commercial oat milk brands use calcium carbonate—essentially ground-up chalk—to enhance their product’s whiteness and creaminess. While the lab confirmed that lead and aluminum levels in these products were within safe limits, health advocates question the necessity of adding chalk to plant-based milk.
Chalk in Your Oat Milk?
Adams, who leads CWC Labs, demonstrated the process by blending pure calcium carbonate into water, producing a liquid visually identical to store-bought oat milk.
"You're drinking chalk milk," Adams remarked, emphasizing that while calcium carbonate is not toxic, its inclusion raises concerns about unnecessary additives in products marketed as natural.
The lab tested several popular oat milk brands, including Chobani, Planet Oat, and Whole Foods’ 365 brand, finding calcium carbonate in all but three: Califia Farms Organic Oat Milk, Oat Malk, and Adams’ own Health Ranger Store Organic Oat Milk Powder.
Heavy Metals: No Red Flags
Despite calcium carbonate’s reputation for potential lead contamination, CWC Labs’ ICP-MS (Inductively Coupled Plasma Mass Spectrometry) testing detected no concerning levels of lead in any of the oat milk samples. Aluminum was present but at trace amounts—ranging from 380 parts per billion (ppb) in Califia Farms to 1,554 ppb in Whole Foods’ 365 brand—far below levels considered hazardous.
"None of these aluminum levels are alarming," Adams stated, noting that many whole foods naturally contain higher aluminum concentrations due to soil absorption.
Why Add Chalk?
Manufacturers add calcium carbonate primarily for two reasons:
Visual Appeal – It mimics the creamy white appearance of dairy milk.
Calcium Fortification – Though Adams argues the bioavailability of calcium from chalk is poor compared to whole-food sources.
Additionally, many brands include thickeners like gellan gum, rapeseed (canola) oil, or sunflower oil—ingredients some consumers may not expect in a product marketed as simple oat milk.
Cleaner Alternatives Exist
For those seeking oat milk without additives, Adams highlighted three options:
Califia Farms Organic Oat Milk – No calcium carbonate, minimal ingredients.
Oat Malk – Contains only oats, water, and Himalayan salt.
Health Ranger Store Organic Oat Milk Powder – A single-ingredient (oats) powdered alternative.
Broader Implications for Plant-Based Milks
The findings extend beyond oat milk. Adams noted that almond and soy milk brands often use similar additives, including calcium carbonate and carrageenan. His advice? "Read labels. If you're not checking ingredients, you're swallowing unknown substances."
While the study reassures consumers about heavy metal safety, it underscores the importance of transparency in plant-based dairy alternatives. As demand grows, so does scrutiny—making clean-label options increasingly vital.
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