Center for Research on Ingredient Safety

What is silver?

Silver is a naturally occurring metal we find in the earth's crust.

Silver isn't a trace mineral needed to support human health, unlike other metals and minerals (e.g., copper, selenium). Therefore, researchers treat silver as an undesired ingredient in most foods and products unless intentionally added.

We typically find silver in consumer product labels as colloidal or ionic silver.

What are silver's proposed properties? Do they kill bacteria?

When applied topically, silver can inhibit the growth and reproduction of bacteria. However, it doesn't destroy bacteria the way bactericidal agents like an antibiotic kills bacteria (1,2).

Silver is considered a bacteriostatic agent, which means it can prevent the multiplication and spread of bacteria, which allows our bodies' immune systems to eliminate potentially harmful bacteria pathogens more easily.

It is important to note that silver's bacteriostatic action depends on many factors, including concentration, particle size, and specific bacterial strains. Additionally, the effectiveness of silver as a bacteriostatic agent may differ among different types of bacteria.

You should avoid consuming ionic or colloidal silver orally. There's no conclusive evidence that orally ingested ionic or colloidal silver possesses the same bacteriostatic properties as topically used silver. In fact, if we consume too much silver, we will develop a permanent condition called argyria that causes skin to turn grey-blue. Silver is also toxic when ingested orally at high enough doses.

What products contain silver?

We find silver in many medical, cosmetic, household, and supplement products, including:

• Antibacterial and Antimicrobial Products
• Clothing and Textiles
• Cosmetics and Personal Care Products
• Jewelry and Accessories
• Silverware and Tableware
• Supplements
• Water Purification Systems 

What is the difference between colloidal and ionic silver?

Colloidal silver and ionic silver are two forms of silver suspensions with many applications. While both types contain silver particles, their composition, and behavior differ.

Let's look at colloidal silver.

Colloidal silver refers to tiny silver particles suspended in a liquid base, typically water. The particles are larger in size and remain dispersed throughout the liquid due to their electrical charge. While the particle size can vary, it's generally within the range of 2 to 500 nanometers.

In a proper colloidal silver solution, the particles remain stable and don't settle to the bottom over time. The silver particles' electrical charges keep them suspended, which repels other particles and prevents aggregation. The concentration of silver in colloidal silver products varies, ranging from very low to high concentrations depending on the product.

Let's look at ionic silver.

Unlike colloidal silver, which contains silver particles, ionic silver does not contain solid particles. Instead, it is composed of silver ions, which are individual silver atoms or molecules carrying a positive charge.

Silver ions are highly reactive and often bind with other molecules present in the liquid. Ionic silver solutions are typically clear or transparent since they do not contain solid particles.

While the silver ions may be dissolved in water, when consumed orally, scientists have found ionic silver deposited in a wide range of organs which can cause adverse health outcomes.

Should I consume colloidal or ionic silver?

You should avoid consuming any product that contains colloidal or ionic silver.

Consuming colloidal silver can cause adverse health effects, including argyria where skin permanently turns grey-blue; it can adversely impact medications causing them to lose efficacy; and it may impair kidney, liver, and nervous systems functions.

While ionic silver has a lower bioavailability than colloidal silver, it can still adversely impact health, including causing argyria.

Should I use products on my skin that contain colloidal or ionic silver?

You can safely use products containing colloidal or ionic silver designed for topical use on your skin.

However, follow the directions, especially if you're using a silver-containing ointment prescribed by a medical provider.

The good news.

Silver-containing ointments and products designed for our skin can be highly effective and safe ways to prevent excessive bacterial growth.

If you have any questions about foods and ingredients, please reach out to us on Twitter, send us an email, or submit your idea to us at go.msu.edu/cris-idea.