Inadequate sun exposure is often blamed for the high prevalence of low vitamin D status, the authors explain, but the truth of this has been unclear.

Dr. Neil Binkley with the University of Wisconsin Osteoporosis Clinical Research Program, Madison, and colleagues investigated the vitamin D status of people living in sun-drenched Hawaii.

The 93 participants in the study spent an average 22.4 hours per week outside without sunscreen and 28.9 hours per week outside with and without sunscreen. This translates to a mean of 11.1 hours per week of total body skin exposure with no sunscreen used, the authors calculate.

Despite this abundant sun exposure, 51 percent of these individuals were found to have low vitamin D levels, the researchers found.

"This implies that the common clinical recommendation to allow sun exposure to the hands and face for 15 minutes may not ensure vitamin D sufficiency," Binkley and colleagues report.

It should not be assumed that individuals with abundant sun exposure have adequate vitamin D status," the team concludes.