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Vitamin D is an important micronutrient for health. Hypovitaminosis D is thought to play a role in the seasonality of a number of diseases and adverse health conditions. To refine hypotheses about the links between vitamin D and seasonal diseases, good estimates of the cyclicality of serum vitamin D are necessary.The objective of this study is to describe quantitatively the cyclicality of 25-hydroxyvitamin D (25OHD) in the United States. We provide a statistical analysis with weekly time resolution, in comparison to the quarterly (winter/spring/summer/fall) estimates already in the literature.We analyzed time series data on 25OHD, spanning 287 consecutive weeks. The pooled data set comes from 3.44 million serum samples from the United States. We statistically analyzed the proportion of sera that were vitamin D sufficient, defined as 25OHD [Formula: see text] ng/mL, as a function of date.In the United States, serum 25OHD follows a lagged pattern relative to the astronomical seasons, peaking in late summer (August) and troughing in late winter (February). Airmass, which is a function of solar altitude, fits the 25OHD data very well when lagged by 8 weeks.Serum vitamin D levels can be modeled as a function of date, working through a double-log transformation of minimal solar airmass (easily calculated from solar altitude, retrievable from an online solar altitude/azimuth table).

To assess vitamin – D deficiency in Northern Pakistan in order to provide inputs towards developing effective preventive and remedial strategies. Methods:A total of five thousand six hundred and ninety three (n=5693) adult patients of both genders were screened for serum Vitamin D-3 levels over the period of six years. Results:Mean serum Vitamin D3 levels among males and females were in insufficient range and showed no significant difference (P>0.05). In study population 56.5% (n=3216) of patients were Vitamin D-3 deficient (30 ng/ml). Significant difference was observed on gender stratification with female population showed higher percentage of deficient levels (79.7%) versus males (20.3%) (p