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Monday Article #5: Colloidal silver

Joyce Ong


Colloidal silver consists of tiny silver particles suspended in a liquid. It is now generally promoted as a dietary supplement.The FDA warned the general public in 1999 that colloidal silver isn’t safe or effective to be used as medication for treating any diseases or conditions. Since then, the FDA and the Federal Trade Commission have taken action against a number of companies for making misleading claims about colloidal silver products.

The effect of colloidal silver on the human body - case study

  • The entire world was introduced to the ‘Blue man’ in 2008, when Paul Karason (AKA the real life ‘Papa Smurf’) came onto the Oprah Winfrey Show​

  • Born with fair skin and strawberry blonde hair, Paul lived a normal life until he saw an add in a magazine for a colloidal silver generator.​

  • It was also rumoured that colloidal silver was used to treat petroleum poisoning- a condition from which his friend suffered. ​

  • Paul began to make a ‘home remedy’ concoction of colloidal silver solution and noticed positive effects including a reduction in acid reflux

  • Due to severe stress, Paul developed an extreme case of dermatitis and began to topically apply colloidal silver over his skin to cure it- this led him to develop an irreversible and rare skin disease called Argyria.

  • Argyria is a condition caused by chronic exposure to silver containing products, causing your skin’s complexion to turn blue-grey. ​

  • Paul specifically developed generalised argyria- which is a gradual blue discolouration of the skin, nails, internal organs and gums due to ingestion and oral consumption of high quantities of silver.​

  • This leads to an accumulation of silver particles trapped under the skin cells- which when exposed to sunlight, tattoo the appearance of the skin. ​

  • Paul later died in 2013 due to a long history of other health problems, including pneumonia, prostate cancer and issues related to the heart- regardless of undergoing a triple bypass surgery a few years ago. ​

  • Astonishingly, from Paul’s autopsy after his death, it showed that Paul’s vital organs were healthy and the silver didn’t damage them​

  • Doctors realised that colloidal silver mainly caused cosmetic changes to skin- and trace amounts of silver can have no major effect on our bodies. ​

  • Paul Karason ended up as a walking cautionary tale and serves as a reminder to us to always seek medical advice from specialists, instead of self-diagnosing and experimenting with our bodies. ​

( References : )

Study on proving claims about colloidal silver

  • The antimicrobial activity of silver nanoparticles was tested against Escherichia coli, aka E-coli. ​

  • Strain B of E-coli was investigated by adding 105 CFU(colony-forming units) of the bacteria on agar plates supplemented with silver nanoparticles with a range of concentrations in regular intervals (10-100, µg cm-3 ).​

  • This was to see the effect of silver nanoparticles on bacteria and in addition there was a plate with no silver which was used as a control​.

  • The experiment was done under incubation for 24h at 37 degree celsius.

  • From the graph we see at 10 µg cm-3 the nanoparticles inhibited 70% of bacterial growth and as the concentrations increased, the number of colonies decreased significantly.

  • At 60 µg cm-3 the number of E.coli colonies was at 0%, meaning 100% inhabitation. In the picture we see physical evidence of the colonies at 0,10,20 and 50 µg cm-3 respectively.

Mechanism of silver nanoparticles in the body ​

When silver nanoparticles (Ag-NPs) reach the gastrointestinal tract through ingestion or inhalation, Ag+ ions get released due to low pH levels in the stomach.​ This occurs through an accelerated process of oxidative dissolution. Oxidative dissolution is a complex chemical reaction influenced by pH, coatings, and ligands in the surrounding fluid. The graph below shows that the rate of dissolution of Ag-NPs to Ag+ is higher in low pH than in high pH levels. This is shown by point 1.

Due to short residence time in the stomach, incomplete dissolution may occur, causing excess silver nanoparticles to be excreted from the body. This is shown by point 2.

The silver ions and its soluble complexes in the gastrointestinal tract can be taken up into circulation by active transport routes for sodium ions and copper ions and enter the bloodstream. Ag–GSH (glutathione-stabilised silver) complexes are important transporters that deliver silver to biological targets through thiolate ligand exchange. Silver readily exchanges between different thiol groups despite the strong Ag–thiol bond, hence thiolate ligand exchange occurs.​ Silver ions are soft acids and thiol groups are soft bases, resulting in a high affinity and stronger bonding between two groups. ​This is shown by point 3.

Occurring afterwards is the photodecomposition of silver biocomplexes containing thiol groups to zerovalent silver nanoparticles when exposed to UV radiation. (UV decomposition is slower in visible light.) Because these decomposition products are zerovalent Ag rather than sulfide phases, the photodecomposition alone is not a sufficient explanation for the known composition of argyrial deposits and an additional mechanism is needed (sulfide and selenide reactions). This is shown by point 4.

This image shows that clear Ag–GSH complexes in deionised water gradually darken over 6 hours under 365 nm UV irradiation but not in room light.

The photoreduced zerovalent metallic silver nanoparticles become immobilised in the basement membrane of the skin's epidermis. The immobilisation is both physical, due to low particle diffusivity, and chemical since the thiol exchange reactions of Ag+ are not possible with Ag. Shown by point 5.

Sulfide-selenium exchange reaction produces Ag2S or Ag2Se, which are the argyrial deposits that cause the skin to appear bluish-grey due to argyria. Shown by point 6.


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