Zeolites are a group of chemically related mineral substances that contain mainly hydrated aluminum and silicon compounds. They occur naturally in volcanic rock and ashes and are also formulated synthetically. Zeolites are marketed as dietary supplements for autism, diarrhea, herpes, hangover, to balance body pH, and as a heavy-metal detoxifier, immunomodulator, and antioxidant.
Industrial and agricultural applications include their use as additives in gravel, detergents, and animal feed, in water and air purifiers, and in some personal care products. Benefits of using zeolites in animal feed include increased mineral utilization (1), reduction of heavy metals-induced anemia (2), and reduction of aflatoxin toxicity (3). However, none of these benefits are applicable to humans. In addition, this use has raised concerns about accumulated tissue aluminum in treated livestock (4) vis-a-vis the known link of aluminum to several morbidities including Alzheimer’s disease (5) (6).
Generally, the various forms of zeolite are not significantly toxic in acute, short-term oral, or parenteral toxicity studies in animals. However, inhalation toxicity is readily demonstrated (7), and airborne zeolite dust has been associated with high incidence of malignant mesothelioma (8) (9) (10) (11), and geologic occurrences of erionite are emerging as a concern for respiratory illness in the United States.
Zeolites have limited use in medicine as an external hemostatic dressing for trauma-related injuries (12), potential for controlled drug delivery, as a suspending agent, or for use in cardiopulmonary bypass and hemodialysis procedures (13) (14) (15).
A small pilot study sponsored by the manufacturer of a proprietary oral zeolite supplement in immunodeficient patients suggests some immunomodulatory effects (16), but no additional studies validate these claims. In an Alzheimer's mouse model, zeolite reduced oxidative damage and plaque generation (17). Two older animal studies suggest that micronized zeolite may have anticancer benefits (18) (19), but this also has not translated into any further studies. Currently, no studies of zeolite as a cancer treatment in humans have been published.
Special Point: A company filed a U.S. patent application in 2001 for a synthesized form of zeolite as a cancer drug (20). Data submitted were based on in vitro, plant, and animal studies. The patent specified that the substance must be injected directly into the tumor, which rules out any benefits by oral route. In addition, the FDA has issued warning letters to several Internet distributors of zeolite products for misleading claims about health benefits (21).