Cold sores are painful, fluid-filled blisters and sores caused by infection with one of two types of the herpes simplex virus. While most Americans are infected with the virus, the Academy of General Dentistry says that only about 30 percent actually develop cold sores. The results of a January 2010 study published in the journal "Cell Biochemistry and Function" by Luisa Gennero, PhD and colleagues suggest that genetic differences in the way the body handles iron partly explain why some people get cold sores and others do not.
History
The relationship between iron and cold sores was first suggested in a July 1995 study published in the "European Journal of Clinical Microbiology and Infectious Diseases" by oral surgeons Philip-John Lamey and Paul A. Biagioni of the Queen's University of Belfast in the United Kingdom. Comparing 41 patients with active cold sores to age- and sex-matched people without cold sores, Lamey and Biagioni found that the cold sore patients had slightly lower levels of the storage form of iron, called ferritin.
Significance
Dr. Gennero's group improved on the first study by looking at genetic differences in a protein called haptoglobin that plays a key role in iron metabolism. One type of haptoglobin leads to higher blood levels of several different forms of iron than the other two. People with this type of haptoglobin were significantly less likely to report a history of cold sores, compared to people with one of two other types of haptoglobin.
Function
Iron is an essential component of an enzyme, ribonucleotide reductase, that the herpes simplex virus requires to infect new cells. However, the T-cells and B-cells of the human immune system that fight the herpes simplex virus also rely on iron. Since, Gennero says, the herpes simplex virus binds iron more effectively than T- and B-cells, when iron is limited, the virus typically wins out, resulting in cold sores.
Solutions
People with low iron levels who suffer from cold sores may benefit from taking iron supplements. In the May 2000 edition of the "European Journal of Clinical Microbiology and Infectious Diseases," oral surgeon Amanda Willis reported that a 325 mg dose of the iron supplement ferrous sulphate, taken three times per day, reduced the incidence of cold sores by nearly 400 percent among 10 people who had low iron stores prior to taking the supplements. Since there's no evidence that iron supplements have any effect on cold sores in people with normal iron levels, people who consider taking iron for cold sores should talk to their doctors about a blood test called ferritin.
Considerations
Iron supplements do not replace conventional medical treatments for cold sores. As with any over-the-counter product, people who take iron supplements should share this information with their health care providers. In addition, while low iron stores may contribute to the risk of cold sores, they are not the only factor. The University of Michigan Health System recommends looking into other nutrient supplements such as vitamin C, vitamin E, zinc and the essential amino acid, lysine. Cold sores usually resolve within 10 to 14 days. Cold sores that last longer than this should be evaluated by a doctor or dentist.
References
- Academy of General Dentistry: What Are Cold Sores?
- "Cell Biochemistry and Function"; Iron Metabolism Markers and Haptoglobin Phenotypes; Luisa Gennaro, Ph.D. et al.; Mar. 2010
- "European Journal of Clinical Microbiology and Infectious Diseases"; Response to Replacement Therapy in Recrudescent Herpes Labialis; Amanda Willis, D.M.D. et al.; May 2000
- University of Michigan Health System: Cold Sores
- "European Journal of Clinical Microbiology and Infectious Diseases"; Relationship Between Iron Status and Recrudescent Herpes Labialis; Philip-John Lamey, D.M.D. and Paul A. Biagioni, D.M.D.; Jul. 1995
