title: Seasonal variations of U.S. mortality rates: Roles of solar ultraviolet-B doses, vitamin D, gene exp ression, and infections.
abstract: Death rates in the U.S. show a pronounced seasonality. The broad seasonal variation shows about 25% higher death rates in winter than in summer with an additional few percent increase associated with the Christmas and New Year's holidays. A pronounced increase in death rates also starts in mid-September, shortly after the school year begins. The causes of death with large contributions to the observed seasonality include diseases of the circulatory system; the respiratory system; the digestive system; and endocrine, nutritional, and metabolic diseases. Researchers have identified several factors showing seasonal variation that could possibly explain the seasonal variations in mortality rate. These factors include seasonal variations in solar ultraviolet-B(UVB) doses and serum 25-hydroxyvitamin D [25(OH)D] concentrations, gene expression, ambient temperature and humidity, UVB effects on environmental pathogen load, environmental pollutants and allergens, and photoperiod (or length of day). The factors with the strongest support in this analysis are seasonal variations in solar UVB doses and 25(OH)D concentrations. In the U.S., population mean 25(OH)D concentrations range from 21ng/mL in March to 28ng/mL in August. Measures to ensure that all people had 25(OH)D concentrations >36ng/mL year round would probably reduce death rates significantly.
authors.affiliation: Sunlight, Nutrition, and Health Research Center, PO Box 641603, San Francisco, CA, 94164-1603, USA. Electronic address: wbgrant@infionline.net.
authors.forename: William B
authors.initials: WB
authors.lastname: Grant
authors.affiliation: Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Nagyerdei blvd 98, Debrecen, H-4032, Hungary.
authors.forename: Harjit Pal
authors.initials: HP
authors.lastname: Bhattoa
authors.affiliation: The Blizard Institute, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Boucher
mesh_terms: D002318:Cardiovascular Diseases / Q000097:blood / Q000235:genetics / Q000401:mortality; D004066:Digestive System Diseases / Q000097:blood / Q000235:genetics / Q000401:mortality; D004785:Environmental Pollutants / Q000009:adverse effects; D015870:Gene Expression; D006801:Humans; D008659:Metabolic Diseases / Q000097:blood / Q000235:genetics / Q000401:mortality; D009026:Mortality; D009748:Nutrition Disorders / Q000097:blood / Q000235:genetics / Q000401:mortality; D052638:Particulate Matter / Q000009:adverse effects; D012141:Respiratory Tract Infections / Q000097:blood / Q000235:genetics / Q000401:mortality; D012621:Seasons; D013472:Sunlight; D014466:Ultraviolet Rays; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D004785:Environmental Pollutants; D052638:Particulate Matter; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: Cardiovascular disease; Gene expression; Mortality rate; Respiratory tract infections; Season; Temperature; Vitamin D