25-Hydroxyvitamin D Levels in Healthy Adults in Hawaii
Endocr Rev, Vol. 32 (03_MeetingAbstracts): P2-130
Copyright © 2011 by The Endocrine Society
Jaya R Kothapally, MD1, Laura Armas, MD1, Mohammed Akhter, PhD1 and Julie A Chang, MD2
Endocrinology (JRK,LA,MA), Creighton University, Omaha, NE
Pulmonary Disease and Critical Care Medicine (JAC), Pulmonary Associates, Aiea, HI
Vitamin D deficiency has been reported in 30% - 50% of adults and children in the lower contiguous United States. Latitude, altitude, season, skin pigmentation, and age are recognized factors that influence how much vitamin D can be made by solar exposure. The aim of this study was to quantify how much sun and skin exposure influence vitamin D status. We report here 25(OH)D levels in healthy adults residing in and around Honolulu, Hawaii (latitude 21.3ºN). The subjects (n=90, age 20-59 yr, females = 63 , males = 27) were a convenient sample of healthy, community-dwelling adults with limited non-solar sources of vitamin D. They reported their race as: 25 Asian/Pacific Islander, 1 Black, not Hispanic, 1 Hispanic, 56 White, not Hispanic, 4 reported more than one.
Data were gathered during March and August. We determined BMI, 25(OH) D levels, sun exposure history and skin exposure history. We used a portable colorimeter that utilizes the CIE L*a*b* color system to measure constitutive skin color of the upper hip and facultative skin color of the dorsal surface of the hand.
The mean (± SD) 25(OH)D levels were 96.9 nmol/L (50.7) with a range from 41-351 nmol/L. 39 (43%) of the study population had 25(OH)D levels less than 80 nmol/L.
The subjects reported a mean (SD) of 34 (±21) hours of sun exposure during a typical week with 41% of skin exposed (equivalent of wearing shorts and T shirt). A sun exposure index was calculated by multiplying the average weekly duration of sun exposure by the percentage of skin exposed during weekdays. There was a correlation between 25(OH)D levels and sun exposure index (Pearson correlation 0.590, P<.0001).
The point at which 95% of the subjects were above 80 nmol/L occurred at a sun index of 15, the equivalent of 16 hours of sun exposure per week in a bikini (90% skin exposure). There was also a correlation between 25(OH)D levels and skin tone and an inverse correlation between 25(OH)D levels and age (Pearson correlation 0.264 and -0.278 respectively, P<0.05).In conclusion, even in the tropics vitamin D status depends on a certain level of sun and skin exposure and casual exposure of hands and face does not appear to be enough. This study gives data to quantify how much sun exposure our skin needs to reach a certain 25(OH)D level.
43% had less than 32 ng, even though on average they had 34 hours of weekly sunlight
Ranged from 16ng to 140 ng of vitamin D
This is far more vitamin D than the Hawaiian teens who were drinking lots of cola
eens Midpoint =30 ng, highest was 62 ng of vitamin D
See PDF at the bottom of this page
UV index >3 is needed to produce Vitamin D
UV index >3 occurs in the middle of the day for 99% of the year in Hawaii
Click here for others
See also Vitamin D Life
- Is 50 ng of vitamin D too high, just right, or not enough
- Traditionally living Africans have 46 ng vitamin D levels – Jan 2012
- Chart of Vitamin D levels vs race - April 2013 has the following