Winter increase in death rate by 25 percent is probably due to low UVB, Vitamin D
Seasonal variations of U.S. mortality rates: Roles of solar ultraviolet-B doses, vitamin D, gene expression, and infections.
J Steroid Biochem Mol Biol. 2017 Jan 11. pii: S0960-0760(17)30003-1. doi: 10.1016/j.jsbmb.2017.01.003. [Epub ahead of print]
Grant WB1, Bhattoa HP2, Boucher BJ3.
1Sunlight, Nutrition, and Health Research Center, PO Box 641603, San Francisco, CA, 94164-1603 USA. Electronic address: wbgrant@infionline.net.
2Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Nagyerdei blvd 98, Debrecen, H-4032, Hungary.
3The Blizard Institute, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
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.
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Vitamin D UK 45 year olds Average vitamin D levels in UK vary with season: 14 ng to 29 ng
Dark gray = 45 year-old MEN, light gray = 45 year-old WOMEN
UV varies a ot more with season at high latitudes
This chart might impliy that the amount of change in seasonal death rate would vary with latitude
Perhaps 35% in Northern Canada, 5% in Tobago, vs 25% in the US
See also web
