Colloidal Silver

Colloidal silver is a liquid solution of tiny silver nanoparticles (under 100 nanometres in size), which are invisible to the human eye [1]. Silver has been used traditionally to stop or prevent infections and kill disease-causing pathogens. It disables oxygen metabolism in bacteria, which leads to the destruction of pathogenic microorganisms [1]. Harmful bacteria such as Escherichia coli and Staphylococcus aureus have been shown to be highly susceptible to colloidal silver treatment in laboratory research [1].

Silver-containing medicines were widely used until the mid-20th century to treat a range of different conditions such as epilepsy, gonorrhea, the common cold, and even cancer [2] [3]. Silver remedies were later replaced with safer therapies, especially after the development of antibiotics for the treatment and prevention of infections [1]. However, there has been a resurgence in the use of colloidal silver as an alternative medicine due to increased resistance of bacteria to antibiotics and an ongoing search for novel antimicrobial agents [1].

Proponents of colloidal silver claim that it can support the immune system and help to treat a range of different diseases from AIDS, to diabetes, and even cancer [3]. However, there is not currently any scientific research in humans to support the oral ingestion of colloidal silver products for the treatment of any disease. In fact, long-term oral use of colloidal silver can cause serious side effects, including permanent skin-discoloration (a condition called argyria), seizures, and kidney damage [3]. The FDA has warned against the oral use of colloidal silver products [2]. They are only approved for topical applications such as skin infections, wound care, and bandages and dressings for the treatment of burns [2].

Nevertheless, there are anecdotal reports of colloidal silver treatment resulting in significant improvements in advanced cancer patients [4]. Laboratory and animal research indicates that silver nanoparticles have antibacterial, antifungal, antiviral, anti-inflammatory, anti-angiogenic and anti-cancer properties [5]. Recent advances in nanotechnology and nanoscience have revealed that silver nanoparticles may have a potential therapeutic role in cancer treatment [5] [6]. However, more research and clinical data is still needed to determine if silver nanoparticles can be safely and effectively used to combat cancer in humans.

History of Colloidal Silver

Silver has been widely used throughout history in various cultures to restrict or prevent the spread of human disease. For thousands of years silver has been used as a healing and anti-bacterial agent by different civilizations across the globe [7]. The earliest recorded use of silver as a medicine dates back to the Han Dynasty in Ancient China around 1500 BC [7]. Silver vessels and plates were frequently used during the ancient empires of Persia, Phoenicia, and Macedonia [7]. In fact, Herodotus, the so-called ‘Father of History’, accounts that all Persian Kings would refuse to drink water unless it came from a silver container, which reportedly kept water fresh for years [8].

Long before the advent of modern medicine silver has been used as a germicide and antibiotic [7]. The medicinal, preservative, and restorative properties of silver can be traced back to the ancient Greek and Roman empires [7]. During the Roman empire the effects of silver were applied to purify water, while silver nitrate was used as a medicine and appears in the Roman pharmacopeia published in 69 BC [8].

During the Middle Ages medicines containing silver such as silver nitrate and silver arsphenamine were given to patients with various different diseases [9]. It was commonly used in hospitals to treat nervous disorders, epilepsy, syphilis, gonorrhea, and other infections [9]. The use of silverware helped to protect families of higher socio-economic classes from the full effects of The Plague. In fact, the use of silver was so commonplace amongst aristocracy that they often developed blue-ish gray skin discolorations from high-levels of silver exposure - a condition known as argyria [7]. It is believed the term “blue blood” was coined to refer to members of nobility in the Middle Ages [7].

Silver has been used for a variety of medical purposes throughout recorded history. Prior to 1938 silver was used to treat various conditions, including cancer. It has been shown to be effective against many different pathogenic organisms, and has been used to treat numerous infectious and noninfectious diseases, sometimes with great success [10]. It was used by soldiers during the First World War to combat infections in wounds. It is also recognized in Ayurvedic medicine as an elixir or rejuvenating agent. Before the introduction of modern antibiotics silver was the most important antimicrobial agent known to man [10].

Since the development of antibiotics the use of silver has dwindled and been replaced by safer alternatives with fewer side effects. However, due to antibiotic resistance there has been a resurgence of interest into the antimicrobial benefits of colloidal silver as well as new research into the potential anticancer effects of silver nanoparticles.

Research on Colloidal Silver

Silver compounds are still widely applied for external use as antiseptics, but in recent years there has been growing interest in using the colloidal form of silver orally as an alternative medication [3]. Laboratory and animal studies indicate potential antitumor effects of silver, but there is currently no clinical research to support the oral use of colloidal silver as a cancer treatment for humans [3]. However, metal nanoparticles, especially silver, are an emerging new class of anti-cancer agents that hold great potential in the field of cancer care [6].

A 2010 in vitro (test tube) study shows that colloidal silver has a dose-dependent toxic effect on breast cancer cell lines and selectively induces apoptosis (programmed cell death) in cancer cells without damaging healthy cells [1]. A 2009 in vitro study on human lung cancer and glioblastoma (brain cancer) cells reveals that silver nanoparticles inhibit cell proliferation (growth and spread) [11]. A more recent 2018 in vitro study indicates that silver nanoparticles could be a promising new approach in the treatment of lung cancer [12], while a 2016 study demonstrates the anticancer effects of silver on human ovarian cancer cell lines [13]. However, clinical research is still needed to determine if these preliminary findings translate into anticancer effects in humans.

Research from 2010 demonstrates the efficacy of biologically synthesized silver nanoparticles in vitro (test tube) and in vivo (animal models) as an antitumor agent for lymphoma [14]. Treatment with silver nanoparticles increased the survival time of tumor-bearing mice by 50% and reduced ascites (fluid build up) by 65% [14]. The results confirm the antitumor properties of silver and suggest a possible role in the treatment of cancer and angiogenesis (blood vessel formation) related disorders. Numerous in vitro and in vivo studies have demonstrated the anti-angiogenic (stops formation of new blood vessels) properties of silver nanoparticles [5] [15] [16]. However, clinical research is still needed to confirm safety and efficacy for cancer treatment in humans.

Despite a lack of scientific evidence on the use of colloidal silver for cancer in humans, there are some case studies where colloidal silver treatment appears to have had remarkable results. A 2018 report details the case of a 78-year-old male with advanced nasal cavity cancer that had spread to the liver and lungs [4]. The patient was rapidly declining in functional capacity and started consuming a homemade silver nanoparticle solution while on hospice care. 18 months later he had complete resolution of his cancer with no toxicities observed. Whether the patient had used any other treatments concurrently was not mentioned in the study.

While silver nanoparticles appear to have a possible therapeutic role in cancer treatment as anticancer agents, it is important to be aware that clinical research is lacking to determine safety and tolerable doses for humans. Silver nanoparticles can also be toxic to healthy tissues with risks of permanent adverse effects and organ damage [6]. Due to the potential for toxicity of silver nanoparticles and their ability to accumulate in and damage healthy tissues, targeted methods of administration directly to cancerous tissues must be developed to ensure safety [6]. Oral administration of high-doses of colloidal silver for systemic effects could result in adverse events.

Potential Applications of Colloidal Silver

The therapeutic potential of silver nanoparticles is related to its unique ability to induce cell death in cancer cells [6]. Following their uptake into a cell via endocytosis (absorption of external material into a cell), silver nanoparticles are collected in endosomes (intracellular sorting organelles) before then being directed to lysosomal fusion (degradation of macromolecules) [6].

The acidic environment created during this process leads to an increased release of silver ions from the silver nanoparticles, which in turn unbalances cellular homeostasis and leads to cell death via apoptosis [6]. In simple terms, this is referred to as a ‘Trojan Horse’ mechanism of action whereby the toxic effects of the silver compounds only occur following their uptake into the cancer cell [6].

Silver nanoparticles have been shown in laboratory and animal studies to possess anticancer activity against a variety of different cancer cell types, including lung, ovarian, breast, neuroblastoma, and numerous others [12]. Research shows that silver nanoparticles generate oxidative stress, cause DNA damage, modulate gene expression and impair mitochondrial function, which triggers a bio-energetic crisis inside the cell and culminates in cell death [12].

In addition to creating oxidative stress and damaging mitochondria, silver has anti-angiogenic properties, which means it may inhibit the formation of new blood vessels and development of tumors [5] [15] [16]. Furthermore, due to its antimicrobial properties silver may also help to eliminate intratumoral bacteria, which has recently been identified as a potential cause of resistance to conventional cancer therapeutics [8] [17] [18] Tumor microenvironments are characterized by hypoxia (low oxygen) and necrosis (decaying tissue), which provides the perfect conditions for bacteria to colonize.

Silver has a long history of use as an antibiotic in human healthcare. Silver-containing compounds and materials are still the workhorse of burn wound care and also play an important role in non-thermal wound treatments in modern medicine [19]. It has been shown to effectively manage wound bioburden (presence of microorganisms), decrease wound inflammation, and improve patient comfort [19]. Silver is also applied in water purification, bone prostheses, reconstructive orthopedic surgery, cardiac devices, catheters and surgical appliances [20].

The antimicrobial action of silver or silver compounds is linked to the bioactive silver ions released and their ability to react with bacterial and fungal cell membranes [20]. The release of silver ions is also related to potential toxicity and dangers of silver compounds. Early forms of silver (such as silver nitrate) have been shown to have more limited utility and higher potential for toxic effects due to their uncontrolled release of silver ions [21] [22]. With more recent advances in nanotechnology certain new silver formulations (such as colloidal forms of silver and silver nanoparticles) show promise as potential anticancer agents, but more research is still needed [21] [22].

Cancer therapy with metal nanoparticles, such as silver, is a highly complex task [6]. In depth testing to understand and characterize the type of cancer being treated is first required [6]. Based on findings, personalized and patient-specific silver nanoparticles treatment protocols can be determined [6]. Due to potential risks of toxicity and bioaccumulation in healthy tissues, methods of targeted application to tumor tissues is required [6]. The application of new innovative silver nanoparticle treatment strategies are currently being designed to be synergistic with standard of care treatments, such as radiotherapy and chemotherapy [6].

There are currently still many challenges when it comes to using silver in cancer care. Nevertheless, with further research in the pipeline, approved clinical treatment regimens incorporating silver-based nanomedicines are believed to not be too far away [6]. However, the use of colloidal silver, especially if taken orally in high concentrations over a long period of time, carries major health risks and the potential for side effects.

Risks and Side Effects of Colloidal Silver

The most serious health risk associated with consuming colloidal silver or other silver-containing medicinals is the onset of a condition called argyria [3]. The long term ingestion of silver can cause silver deposition in the skin and mucous membranes, which results in a bluish-gray discoloration of your skin, eyes, organs, nails and gums [3]. Argyria does not normally cause major health problems aside from the cosmetic concerns. In most cases, the condition is irreversible.

In rare cases, other adverse effects of consuming colloidal silver include seizures and kidney damage [3]. Pregnant women should not consume colloidal silver as it can also cause developmental issues in the fetus [3]. Colloidal silver products may also interact with certain antibiotics and thyroid medications [23].

In 1999 the FDA warned that colloidal silver is not safe or effective for treating any disease or health condition [23]. The risks of consuming silver orally were deemed to outweigh any potential benefits [2].

Currently, the only approved medical applications of colloidal silver products are for topical use. However, with recent advances in nanomedicine and targeted therapeutic applications of silver nanoparticles, this may change in the future.