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From Medical News Today:

Quote:

The Possible Roles Of Solar Ultraviolet-B Radiation And Vitamin D In Reducing Case-Fatality Rates From The 1918-1919 Influenza Pandemic In EU

22 Jun 2009

An estimated 675,000 Americans died from the A/H1N1 pandemic influenza in the United States in 1918-1919. Many of these deaths were from ensueing bacterial pneumonia rather than directly from the viral infection. The United States Public Health Service conducted surveys in twelve cities and rural areas of the country in late 1918 to early 1919 to determine the case-fatality rate in each city or area. Case-fatality rates varied from 0.78 deaths/100 cases in San Antonio, Texas to 3.14 deaths/100 cases in New London, Connecticut. The strong variation with location suggested that solar ultraviolet-B (UVB) irradiance, through production of vitamin D, reduced the risk of death following infection by this pandemic influenza.

To investigate this possibility, the case-fatality rate data were compared statistically with solar UVB doses in July and January. Strong correlations with UVB doses were found for both indices.

There are two mechanisms whereby vitamin D can reduce the risk of death once the pandemic influenza virus infection took hold: reduced production of proinflammatory cytokines and reduced risk of bacterial pneumonia. The hormonal metabolite of vitamin D, 1,25-dihydroxyvitamin D, reduces the production of cytokines from T-helper 1 type (proinflammatory). 1,25-dihydroxyvitamin D also induces the production of human cathelicidin, LL-37, which has both antimicrobial and antiendotoxin properties. LL-37 has been found effective in reducing the risk of several types of bacteria, and is also thought to reduce the risk of respiratory viral infections including seasonal influenza.

Whether this finding is relevant to the current A/H1N1 influenza virus outbreak is unknown but should be evaluated.

"The authors propose a very interesting hypothesis based on intriguing observations that vitamin D deficiency and influenza infection share a similar pattern in incidence during the year. Recent work by several groups have demonstrated that vitamin D induced anti-microbial peptides that may be important for the immune defense against pathogens such as virus. As we are entering the fall and winter season, it may be worth considering addressing vitamin D status in individuals at risk for influenza infection."

Link to paper describing the ecological study*

Source: Sunlight, Nutrition and Health Research Center (SUNARC)

http://www.medicalnewstoday.com/articles/154759.php

Quote:

* The possible roles of solar ultraviolet-B radiation and vitamin D in reducing case-fatality rates from the 1918–1919 influenza pandemic in the United States

William B. Grant and Edward Giovannucci

Volume 1, Issue 4
July/August

Deaths during the 1918–1919 influenza pandemic have been linked to both the influenza virus and secondary bacterial lung infections. Case fatality rates and percentage of influenza cases complicated by pneumonia were available from survey data for twelve United States locations in the 1918–1919 pandemic. This study analyzes case fatality rates and cases complicated by pneumonia with respect to estimated summertime and wintertime solar ultraviolet-B (UVB) doses as indicators of population mean vitamin D status. Substantial correlations were found for associations of July UVB dose with case fatality rates (r = -0.72, p = 0.009) and rates of pneumonia as a complication of influenza (r = -0.77, p = 0.005). Similar results were found for wintertime UVB. Vitamin D upregulates production of human cathelicidin, LL-37, which has both antimicrobial and antiendotoxin activities. Vitamin D also reduces the production of proinflammatory cytokines, which could also explain some of the benefit of vitamin D since H1N1 infection gives rise to a cytokine storm. The potential role of vitamin D status in reducing secondary bacterial infections and loss of life in pandemic influence requires further evaluation.

Authors

William B. Grant
Corresponding author: wbgrant~infionline.net

Sunlight, Nutrition and Health Research Center (SUNARC)

Edward Giovannucci
Departments of Nutrition and Epidemiology; Harvard School of Public Health; and Department of Medicine; Brigham and Women’s Hospital; Boston, MA USA

http://www.landesbioscience.com/jou...gy/article/9063