Seasonal Changes in Vitamin D Levels in Estonia
Author Information
Author(s): Mart Kull, Riina Kallikorm, Anu Tamm, Margus Lember
Primary Institution: University of Tartu
Hypothesis
What are the seasonal variations of vitamin D levels in the general population of Estonia?
Conclusion
Vitamin D insufficiency is highly prevalent throughout the year in a population without vitamin D dairy fortification living at the latitude of 59°N.
Supporting Evidence
- 73% of subjects had vitamin D insufficiency in winter.
- In summer, only 29% of subjects were vitamin D insufficient.
- The mean serum 25(OH)D concentration increased significantly from winter to summer.
Takeaway
People in Estonia often don't get enough vitamin D, especially in winter when it's hard to get from the sun.
Methodology
The study involved a random selection of 367 individuals, measuring their vitamin D levels in summer and winter, along with recording demographics and sunbathing habits.
Potential Biases
Participants with higher vitamin D levels were more likely to attend follow-up tests, which could introduce bias.
Limitations
The study may overestimate vitamin D levels due to higher sun exposure in the summer of 2006 compared to previous years.
Participant Demographics
The participants included 200 women and 167 men, aged 25 to 70 years, with a mean age of 48.9 years.
Statistical Information
P-Value
p < 0.0001
Confidence Interval
95% CI 0.6–8.2
Statistical Significance
p<0.0001
Digital Object Identifier (DOI)
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