We have been discussing the importance of Vitamin D and adequate sunlight recently. And, the importance of maintaining a healthy weight as this actually raises your serum Vitamin D levels. Often we hear the only way to get adequate Vitamin D is to take a supplement, especially if you are older, as you lose your ability to synthesize Vitamin D from the sun.

However, contrary to a these many admonitions claiming that Americans, especially seniors, must take vitamin D supplements because their skin can no longer generate sufficient vitamin D when out in the sun, seniors' vitamin D generating capability is apparently just as good as that of young people, as this recent study reports.

Am J Epidemiol. 2008 Sep 15;168(6):577-86. Epub 2008 Jun 25.

Frequency of Leisure-Time Physical Activity and Serum 25-Hydroxyvitamin D Levels in the US Population: Results from the Third National Health and Nutrition Examination Survey.Scragg R, Camargo CA Jr.

The decline in vitamin D status among older people is probably due to decreased synthesis of vitamin D by sun-exposed skin and/or decreased outdoor activity. The authors examined the association between outdoor
leisure physical activity and serum 25-hydroxyvitamin D in the Third National Health and Nutrition Examination Survey (1988-1994) (n = 15,148 aged >/=20 years). The mean 25-hydroxyvitamin D concentration declined with increasing age, with 79, 73, and 68 nmol/liter for persons aged
20-39, 40-59, and 60 or more years. The proportion that engaged in outdoor activity in the past month was 80% for persons aged 20-39 and 40-59 years but 71% for those aged 60 or more years. In contrast, the
mean difference in 25-hydroxyvitamin D between those who participated in outdoor activities daily compared with those who did not participate in the past month was similar for the youngest and oldest age groups: 13
and 16 nmol/liter, respectively. Those persons aged 60 or more years who participated in daily outdoor activities had a mean 25-hydroxyvitamin D concentration similar to that of persons aged 20-39 years: 77 versus 79 nmol/liter, respectively. These nationally representative data suggest that persons aged 60 or more years can synthesize enough vitamin D from daily outdoor activities to maintain vitamin D levels similar to those of young adults.

PMID: 18579538

So, don't forget to get out and get some sun. Not only is participating in outdoor activity a great way to get fresh air and exercise, it is also a way of getting enough sun.

In Health
Jeff