[Ultraviolet radiation impact on seasonal variations of serum 25-hydroxy-vitamin D in healthy young adults in Buenos Aires].

Exposure to sunlight (ES) is the main source of vitamin D. There are few reports regarding the seasonal variations of serum 25(OH) vitamin D in young adults and its correlation with ultraviolet radiation dose (UVRd). Our aims were to determine 25OHD variations in young adults and assess the correlation between 25OHD levels, dietary calcium intake (DCI) and the UVRd. Eighty two healthy volunteers were prospectively studied: 42 women and 40 men. Serum 25OHD, calcium, phosphorus and magnesium were measured at the end of winter and at the end of summer. ES and UVRd were determined hourly in winter and summer. Seasonal variation in serum 25OHD levels was observed with significantly higher levels in summer in both gender. Serum 25OHD <20 ng/ml was more frequently found in winter (42.6% in women and 50% in men). The ES and UVRd were significantly lower in winter vs. summer. ES and UVRd positively correlated with 25OHD only in winter in both men and women. DCI was lower than recommended and did not correlate with 25OHD levels.