Bentonite Clay

Medically reviewed by Prof. Giorgi Pkhakadze, MD, MPH, PhD — GMJ Editorial Board

What is Bentonite Clay?

Bentonite clay is a naturally occurring absorbent aluminum phyllosilicate clay formed from volcanic ash weathering over millions of years. The most common and studied form is sodium bentonite (montmorillonite), which has unique swelling and adsorption properties when mixed with water. Named after Fort Benton, Wyoming, where large deposits were first identified, bentonite clay has been used for centuries in traditional medicine and is now marketed as a dietary supplement for detoxification purposes.

Note: The categorization as an omega/fatty acid supplement is incorrect – bentonite clay is an inorganic mineral clay with no fatty acid content. It belongs to the category of detoxification or mineral supplements.

Health benefits & uses

Digestive health support (Limited evidence): Some small studies suggest bentonite clay may help with digestive issues, though robust clinical evidence is lacking. A study in rats showed potential benefits for irritable bowel syndrome symptoms, but human data remains insufficient.

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Toxin binding and removal (Limited evidence): Laboratory studies demonstrate bentonite clay’s ability to bind various toxins, heavy metals, and mycotoxins in test-tube conditions. However, there’s minimal evidence that oral consumption effectively removes toxins from the human body or provides clinically meaningful detoxification benefits.

Skin health (Limited evidence): When applied topically, bentonite clay may help absorb excess oils and impurities from skin, though this use is primarily cosmetic rather than therapeutic.

Diarrhea management (Limited evidence): Some traditional and anecdotal reports suggest bentonite clay may help with acute diarrhea, but controlled clinical trials are lacking.

How it works

Bentonite clay’s primary mechanism involves its unique crystalline structure, which creates a large surface area with negative electrical charge. This structure theoretically allows it to attract and bind positively charged particles, including some toxins, bacteria, and metals through a process called adsorption. When hydrated, bentonite clay can expand up to 18 times its dry volume, potentially increasing its binding capacity.

However, the digestive tract’s complex environment, including varying pH levels, digestive enzymes, and competing ions, may significantly impact these binding properties. The clay’s effectiveness in vivo differs considerably from controlled laboratory conditions.

Dosage

No official recommended daily allowance (RDA) or upper limit (UL) exists for bentonite clay, as it’s not recognized as an essential nutrient. Typical supplement recommendations range from 1-2 teaspoons (approximately 5-10 grams) mixed with water, taken 1-2 hours away from meals and medications.

Important considerations:

• Start with smaller amounts to assess tolerance
• Always mix with adequate water to prevent intestinal blockage
• Take separately from medications and other supplements
• Consult healthcare providers before use, especially for extended periods

Food sources

Bentonite clay is not naturally found in foods. It’s exclusively available as a processed supplement in powder, capsule, or liquid form. Some food-grade bentonite clay products are marketed for internal use, but quality and purity can vary significantly between manufacturers.

Safety & side effects

Bentonite clay consumption carries several potential risks:

Common side effects:

• Constipation or intestinal blockage if insufficient water is consumed
• Electrolyte imbalances with prolonged use
• Reduced absorption of nutrients and medications

Serious concerns:

• Heavy metal contamination: Some bentonite clay products contain harmful levels of lead, arsenic, or other heavy metals
• Intestinal obstruction risk, particularly with inadequate hydration
• Potential interference with essential mineral absorption

The FDA has issued warnings about lead contamination in some bentonite clay products, particularly those not intended for internal consumption.

Interactions

Drug interactions: Bentonite clay may significantly reduce absorption of various medications, including:

• Antibiotics
• Heart medications
• Psychiatric medications
• Thyroid hormones

Supplement interactions: May interfere with absorption of vitamins, minerals, and other supplements, particularly fat-soluble vitamins (A, D, E, K) and essential minerals like iron, calcium, and zinc.

Maintain at least 2-hour separation between bentonite clay and any medications or supplements.

Who should be cautious

The following groups should avoid or exercise extreme caution with bentonite clay:

• Pregnant and breastfeeding women due to potential heavy metal exposure
• Children, who may be more susceptible to contamination risks
• Individuals with constipation or digestive blockage history
• People taking essential medications that require consistent absorption
• Those with kidney or liver disease
• Individuals with electrolyte imbalances

Frequently asked questions

Does bentonite clay really detox the body?

While bentonite clay can bind certain substances in laboratory conditions, there’s limited scientific evidence that oral consumption provides meaningful detoxification benefits in humans. The liver and kidneys already effectively detoxify the body naturally.

Is food-grade bentonite clay safe for internal use?

Even food-grade products may contain contaminants. The FDA has found lead and other heavy metals in various bentonite clay products. Third-party testing for purity is essential, and even then, safety isn’t guaranteed.

How long can I safely take bentonite clay?

Long-term safety data is lacking. Most practitioners recommend short-term use only (days to weeks) rather than continuous supplementation, due to risks of nutrient depletion and contamination exposure.

Can bentonite clay help with weight loss?

There’s no scientific evidence supporting bentonite clay for weight loss. Any temporary weight reduction would likely be due to water loss or reduced food absorption, which isn’t healthy or sustainable.

Should I take bentonite clay with or without food?

Most recommendations suggest taking bentonite clay away from meals (1-2 hours before or after eating) to minimize interference with nutrient absorption and to potentially maximize its purported binding effects.