MRSAPatient friendly summary

  • Sunlight can increase the risk of MRSA by suppressing the skin’s immune system.
  • Vitamin D can lower the risk of MRSA by strengthening the body’s immune system.

Methicillin-resistant Staphylococcus aureus (MRSA) is a staph bacteria that is resistant to certain antibiotics.

An MRSA infection first appears on the skin as small red pimples or insect bites. The pimples may soon become deep abscesses that need to be surgically drained. They are very painful.

MRSA may remain on the skin, or it may move into other body parts. Infections have been noted in the bones and joints, the bloodstream and heart valves, and lungs. People who have had surgery may develop MRSA in their wounds. Some MRSA infections can be life-threatening.

Risk factors

People with weakened immune systems (those with HIV/AIDS and the elderly) are at increased risk of MRSA infection.

Sunlight exposure and MRSA risk

MRSA infections are more common in the summer and in the southern United States. Long-wave ultraviolet (UVA) light may suppress the body’s innate immune system. This system protects the skin against infections.

Vitamin D and MRSA

Vitamin D levels

In the United States, people with vitamin D deficiency were twice as likely to have MRSA bacteria in their nose.

How vitamin D works

Vitamin D may protect against MRSA by strengthening the body’s innate immune system. Vitamin D triggers production of cathelicidin and defensins. These proteins have antibacterial properties.


Based on studies of other diseases, vitamin D levels above 30–40 ng/mL (75–100 nmol/L) may reduce the risk of MRSA.

However, UV light may increase the risk of MRSA. Those with higher risk of MRSA should consider obtaining vitamin D from supplements rather than UVB exposure.


Higher blood levels of vitamin D are likely to help fight MRSA infection. However, no such studies have been reported.

Find out more...

We will be adding a detailed evidence summary on this topic in the near future.  Please check back soon to find out more.

Page last edited: 17 May 2011