Too Much Sun?

Sun exposure and Vitamin DVitamin D (also known has the sunshine vitamin) is an essential hormone which your body needs to absorb calcium for strong bones and for numerous other functions in the body. It’s so vital for optimal health that studies have shown people with higher levels of vitamin D have a lower risk of disease.

Vitamin D is something your body can produce, your skin and the sun work together to synthesize vitamin D but there’s new research that suggests too much exposure could limit your Vitamin D production and leave you deficient.

Study Sun Exposure and Vitamin D

In a study comprised of 1000 males and females between the ages of 13 and 82, participants were selected based on regular sun exposure without sunscreen and a routine that did not include taking vitamin D supplements. Participants skin type was assessed using the Fitzpatrick Skin Phototype Scale, a standard numerical measurement used by dermatologists and a sun index was calculated for each participant using their amount of sun exposure and the fraction of skin exposed.

Researchers compared sun index and skin type to levels of vitamin D found in the blood. They found that 72 percent of the participants were vitamin D deficient.

“Our findings suggest that skin tanning, which is a natural protection against the harmful effects of UV irradiation, limits the progressive rise in serum vitamin D towards optimal concentrations,” said study author Dr. Francisco Bandeira, of the University of Pernambuco Medical School in Recife, Brazil. –

Despite living in tropical regions, near the equator, and getting very high rates of sun exposure most people had serum vitamin D below 30 ng/ml [nanograms per milliliter], which is considered the cutoff for normal.


Based on this study it would seem too much sun may work to reduce levels of vitamin D. While 30 minutes of unprotected sun exposure should be enough to maintain healthy levels, you’re also exposing yourself to harmful UV radiation. The American Academy of Dermatology recommends against getting vitamin D from unprotected exposure to sunlight. Check with your doctor for the best way to maintain a healthy level of vitamin D with a combination of sun exposure, foods, and supplements.