A new study reports that vitamin D levels in Sao Paulo, Brazil, are good in the young and active during the summer, while not in the winter and that the elderly have poor levels year round.
Sao Paulo sits at 23 degrees south of the equator and has subtropical weather. This creates a unique opportunity to study the city’s population and observe vitamin D levels in people who get good amounts of sun exposure to those who do not.
The researchers studied four different groups of people and their vitamin D levels. The distinct groups were nursing home residents, middle-class community dwellers, physically active elderly and a group of young individuals, age 17-35. In the first two groups, the populations were 90-95% white, 5-10% black. In the latter two groups, the populations were 60-75% white, 20% Asian and 5-12% black.
Here’s what they found:
- The young group had vitamin D levels of 41 ng/ml in the summer, 28 ng/ml in the winter.
- The physically active had vitamin D levels of 37 ng/ml in the summer, 32 ng/ml in the winter.
- Community dwellers had vitamin D levels of 24 ng/ml in the summer, 18 ng/ml in the winter.
- Nursing home residents had vitamin D levels of 17 ng/ml in the summer, 14 ng/ml in the winter.
The authors concluded,
“We found very low 25(OH)D concentrations for the elderly when compared to younger people. This finding is possibly due to age and habit-related sunlight exposure differences. The existence of a seasonal variation over 25(OH)D concentrations is evident, as well as the influence of age is.”
More research is needed to see if vitamin D levels drop during the winter time due to decreased sun exposure habits, less UV intensity or a combination of both.