A new study has found that Australians who followed the current sun exposure guidelines were insufficient in vitamin D during the winter.
The sun is the most natural source of vitamin D, but also the major cause of certain types of skin cancers. Sun exposure guidelines have been developed in Australia in an effort to balance the beneficial and harmful effects of sun exposure.
Researchers recently evaluated whether the guidelines would maintain healthy levels of vitamin D in individuals who followed them. In order to do this, participants were asked to follow specific guidelines for sun exposure. These guidelines stated:
- September to April, during the months with high UVR: A few minutes at mid-morning or mid-afternoon on most days of the week. If the participants had darker skin, 3-6 times this amount was recommended.
- May to August, during the months with low UVR: About 2-3 hours around midday and spread across the week. Again, if the participants had darker skin, 3-6 times this amount was recommended.
Participants recorded whether they complied with these guidelines. The researchers then measured the vitamin D levels.
A total of 99 participants completed the winter study and 104 participants completed the summer study. The average vitamin D levels in participants who complied with the guidelines were 26.9 ng/ml and 16.8 ng/ml in summer and winter, respectively.
The researchers concluded,
“When compared with the summer group, winter participants were much less likely to achieve the recommended amount of sun exposure. Even if obtained, this exposure was unlikely to result in a 25(OH)D concentration [greater than] 50 nmol/L (20 ng/ml).”