October 2020 Issue

Ask the Expert: Colloidal Silver and Cancer
By Toby Amidor, MS, RD, CDN, FAND
Today’s Dietitian
Vol. 22, No. 8, P. 8

Q: Some clients have been asking whether taking supplemental colloidal silver helps treat cancer. What does the evidence say?

A: There are many claims to the use of colloidal silver, including treating and preventing infections, hay fever, skin conditions, and cancer, and boosting immunity. However, there’s no strong research to support its use for any of these reasons. Furthermore, there’s evidence it can be dangerous. This article focuses on the science surrounding cancer treatment.

Colloidal silver is a suspension of microscopic silver particles in a fluid base. Silver has no known physiological function and isn’t an essential nutrient.1

According to the Natural Medicines Database, although colloidal silver drugs were once available over the counter and via prescription, in 1999 the FDA ruled that colloidal silver isn’t considered safe or effective.1 However, colloidal silver products still are being promoted and sold as homeopathic remedies and dietary supplements.

Some cell studies show possible benefits of colloidal silver for cancer prevention and treatment. A 2010 in vitro study examined the effects of colloidal silver on breast cancer cells, showing a possible apoptotic effect on MCF-7 breast cancer cells. Researchers concluded that colloidal silver might be a potential alternative agent for human breast cancer therapy but that more research is needed.2

A 2016 in vitro study looked at colloidal silver’s relationship to immunological parameters in leukemia and lymphoma cancer cell lines. Several markers, including interleukin 2, were significantly reduced, leading researchers to conclude that colloidal silver is nontoxic to the immune system cells and may decrease cancer cell proliferation.3 Despite these positive results, no human studies have been conducted that would strengthen silver’s alleged benefit for cancer treatment.

To that end, according to the Memorial Sloan Kettering Cancer Center, silver compounds are used externally to stop or prevent infections but there’s no evidence that colloidal silver has cancer-fighting effects in humans.4

Furthermore, the risks of consuming silver can far outweigh the potential benefits. According to the National Institutes of Health, there’s no known safety or efficacy data on dietary supplements containing colloidal silver. But studies have shown that long-term oral use can be harmful. Oral colloidal silver products become most concentrated in the liver, skin, spleen, and adrenals and build up in smaller amounts in the muscles and brain.5 Silver build-up in the skin, a condition known as argyria, can cause the skin to take on an irreversible bluish color that first appears in the gums. It also can stimulate melanin production in the skin, and areas exposed to the sun become increasingly discolored.4

Recommendations for Clients
Many reputable organizations warn against the use of colloidal silver for a variety of diseases including cancer. There are insufficient data to make any of these claims. If a client is taking colloidal silver, the RD should review medications, as numerous interactions are associated with them, including synthroid, penicillanine (Cuprimine, Depen), quinolone antibiotics, and tetracycline antibiotics, and with herbs and supplements such as iodine and selenium. It’s also contraindicated during pregnancy and can potentially harm the fetus.1

— Toby Amidor, MS, RD, CDN, FAND, is the founder of Toby Amidor Nutrition (http://tobyamidornutrition.com) and a Wall Street Journal best-selling author. Her cookbooks include The Best Rotisserie Chicken Cookbook, The Create-Your-Plate Diabetes Cookbook, Smart Meal Prep for Beginners, The Easy 5-Ingredient Healthy Cookbook, The Healthy Meal Prep Cookbook, and The Greek Yogurt Kitchen. She’s a nutrition expert for FoodNetwork.com and a contributor to U.S. News Eat + Run and other national outlets.


1. Colloidal silver. Natural Medicines website. https://naturalmedicines.therapeuticresearch.com/databases/food,-herbs-supplements/professional.aspx?productid=779

2. Franco-Molina MA, Mendoza-Gamboa E, Sierra-Rivera CA, et al. Antitumor activity of colloidal silver on MCF-7 human breast cancer cells. J Exp Clin Cancer Res. 2010;29(1):148.

3. Franco-Molina MA, Mendoza-Gamboa E, Zarate-Triviño DG, et al. In vitro evaluation of colloidal silver on immune function: antilymphoproliferative activity. J Nanomater. 2016;2016:4176212.

4. Colloidal silver. Memorial Sloan Kettering Cancer Center website. https://www.mskcc.org/cancer-care/integrative-medicine/herbs/colloidal-silver. Updated April 24, 2020.

5. Colloidal silver. National Center for Complementary and Integrative Health website. https://www.nccih.nih.gov/health/colloidal-silver. Updated April 2017.