Introduction: zeolites (clinoptilolites) are a family of alluminosilicates and cations clustered to form macro aggregates by small individual cavities. In the medical area they are involved in detoxification mechanisms capturing ions and molecules into their holes. Actually, we classify about 140 types of natural and 150 synthetic zeolites, for specific and selective use. Clinoptilolite is a natural zeolite and it is the most widespread compound in the medical market.

Objective: this review analyzes the main fields of zeolite utilization.

Methods: we searched Pubmed/Medline using the terms "zeolite" and "clinoptilolite".

Results and discussion: in zoothechnology and veterinary medicine zeolite improves the pets' fitness, removes radioactive elements, aflatoxines and poisons. Zeolite displays also antioxidant, whitening, hemostatic and anti-diarrhoic properties, projected in human care. However very scanty clinical studies have been run up to now in immunodeficiency, oncology after chemotherapy and radiotherapy as adjuvants.

Conclusions: further clinical investigations are urgently required after this review article publication which updates the state of the art.

Unique and outstanding physical and chemical properties of zeolite materials make them extremely useful in a variety of applications including agronomy, ecology, manufacturing, and industrial processes. Recently, a more specific application of one naturally occurring zeolite material, clinoptilolite, has been widely studied in veterinary and human medicine. Due to a number of positive effects on health, including detoxification properties, the usage of clinoptilolite-based products in vivo has increased enormously. However, concerns have been raised in the public about the safety of clinoptilolite materials for in vivo applications. Here, we review the scientific literature on the health effects and safety in medical applications of different clinoptilolite-based materials and propose some comprehensive, scientifically-based hypotheses on possible biological mechanisms underlying the observed effects on the health and body homeostasis. We focus on the safety of the clinoptilolite material and the positive medical effects related to detoxification, immune response, and the general health status.

The severity of osteoporosis in humans manifests in its high incidence and by its complications that diminish quality of life. A societal consequence of osteoporosis is the substantial burden that it inflicts upon patients and their families. Several bone-modifying drugs have been prescribed to patients with osteoporosis. However, evidence for their anti-fracture efficacy remains inconclusive. To the contrary, long-term use of anti-osteoporotic drugs such as bisphosphonates and Denosumab, an RANKL inhibitor, have resulted in adverse events. We now present an alternative and adjuvant approach for treatment of osteoporosis. The data derive from in vivo studies in an ovariectomized rat model and from a randomized double blind, placebo-controlled human clinical study. Both studies involved treatment with Panaceo Micro Activation (PMA)-zeolite-clinoptilolite, a defined cation exchange clinoptilolite, which clearly improved all bone histomorphometric parameters examined from ovariectomized animals, indicative for increased bone formation. Moreover, intervention with PMA-zeolite-clinoptilolite for one year proved safe in humans. Furthermore, patients treated with PMA-zeolite-clinoptilolite showed an increase in bone mineral density, an elevated level of markers indicative of bone formation, a significant reduction in pain, and significantly improved quality of life compared with patients in the control (placebo) group. These encouraging positive effects of PMA-zeolite-clinoptilolite on bone integrity and on osteoporosis warrant further evaluation of treatment with PMA-zeolite-clinoptilolite as a new alternative adjuvant therapy for osteoporosis.

Natural silicate materials, including zeolite clinoptilolite, have been shown to exhibit diverse biological activities and have been used successfully as a vaccine adjuvant and for the treatment of diarrhea. We report a novel use of finely ground clinoptilolite as a potential adjuvant in anticancer therapy. Clinoptilolite treatment of mice and dogs suffering from a variety of tumor types led to improvement in the overall health status, prolongation of life-span, and decrease in tumors size. Local application of clinoptilolite to skin cancers of dogs effectively reduced tumor formation and growth. In addition, toxicology studies on mice and rats demonstrated that the treatment does not have negative effects. In vitro tissue culture studies showed that finely ground clinoptilolite inhibits protein kinase B (c-Akt), induces expression of p21WAF1/CIP1 and p27KIP1 tumor suppressor proteins, and blocks cell growth in several cancer cell lines. These data indicate that clinoptilolite treatment might affect cancer growth by attenuating survival signals and inducing tumor suppressor genes in treated cells.

Two different natural zeolites from Cuba and Mexico, which are already being used as contemporaneous drugs or dietary supplements in Germany and Mexico, respectively, are applied in a comparative study of their histamine-binding capacities as a function of their particle sizes. The zeolites are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and N₂-sorption measurements (BET surface areas). The Cuban zeolite contains clinoptilolite and mordenite as major phases (78% zeolite), whereas the Mexican one contains only clinoptilolite (65% zeolite). Both zeolites are apparently free from fibrous materials according to SEM. Both zeolites adsorb significant amount of histamine under the experimental conditions. Nevertheless, the results showed that the histamine-binding capacity of the Cuban zeolite is higher than the Mexican one and the smaller the particle size of zeolite, the higher the histamine-binding capacity. This difference could be due to the variation in their mineralogical compositions resulting in varied BET surface areas. Thus, the high histamine-binding capacities of Cuban zeolites seem to be due at least partly to the presence of the large-pore zeolite mordenite, providing high total pore volumes, which will be discussed in detail. For the first time, we have shown that the mineralogical compositions of natural zeolites and their particle sizes play a key role in binding histamine, which is one of the most important regulators in human physiology.

Ammonium, from separately collected human urine, had been removed through transfer onto the ammonium selective natural zeolite, clinoptilolite, through ion exchange. In the subsequent treatment steps of washing with tap water, ammonium removed from urine was eluted from the surface of the clinoptilolite to be recovered for further reuse. Different quantities of clinoptilolite were used for a survey of the capacity of the zeolite for the process and to identify removal efficiencies based on initial ammonium loads. The highest surface concentration attained under experimental conditions employed was 15.44 mg ammonium per gram of clinoptilolite for an initial concentration of 110 mg ammonia per litre, and the highest removal was 98%, obtained for a loading of 1 mg ammonium per gram clinoptilolite. In the subsequent elution process, better removals were observed as pH was increased and the highest removal was attained at pH 13. The recovery was calculated as 9.73 mg ammonium per gram of clinoptilolite, corresponding to an efficiency of 63% only through washing with tap water. The results have given positive indications for the possibility of using ion exchange with clinoptilolite for the removal of ammonium from human urine and an incentive for improving methods of elution for its recovery for further reuse.