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Obesity boosts, vitamin D cuts swine flu death risk

Being obese, particularly extremely or morbidly obese boosts risk of death from viruses and viral diseases like H1n1 or swine flu infection, a new study in the Feb 1, 2011 issue of Clinical Infectious Diseases.

The study led by Janice K. Louie and colleagues of California Department of Public Health in Richmond, California showed about 50 percent of Californians aged 20 or older who died from H1N1 or were hospitalized for the infection in 2009 were obese.

A person with his body mass index of greater than 30 or 40 kilos per meter squared is by definition obese or extremely obese respectively.

For the study, the researchers looked at 534 adult cases of 2009 pandemic influenza A or H1N1 infection and observed that 43 percent of patients were aged 50 years or older and 72 percent had influenza-related high risk conditions recognized by the CDC Advisory Committee on Immunization Practice.

Fifty-one percent of H1N1 patients had a BMI of greater than 30.  Among those who died, 61 percent had a BMI of greater than 30 and 30 percent had a BMI of greater than 40 or were extremely obese.

Being obese (BMI greater than 30) or extremely obese (BMI greater than 45) was correlated with 200 or 300 percent increased risk of death from H1N1 virus, respectively.

The researchers concluded "Half of Californians ≥20 years of age hospitalized with 2009 H1N1 infection were obese. Extreme obesity was associated with increased odds of death. Obese adults with 2009 H1N1 infection should be treated promptly and considered in prioritization of vaccine and antiviral medications during shortages."

"They (extremely obese persons) should also see their health provider early if symptoms of influenza develop, so that they can get diagnosed and treated as quickly as possible. This is especially important if the influenza virus is known to be circulating in the community and causing illness," Dr. Louie said. 

Dr. Louie also said more research is needed to help understand why extremely obese people are more likely to die from the 2009 H1N1 influenza infection.

The fact that extremely obese people are at higher risk of death from H1N1 infection may have something to do with their low vitamin D status, a health observer suggested.

According to Dr. John Cannell, a vitamin D expert and director of Vitamin D Council, two physicians, one in Wisconsin and the other in George reported evidence that suggests taking high doses of vitamin D prevented H1N1 infection.

And Fish E. and colleagues of University of Wisconsin School of Medicine and Public Health reported in the Dec 2010 issue of the Journal of Surgical Research that 84 percent of morbidly obese patients were vitamin D deficient.

The researchers suggested that elevated BMI and increasing degrees of obesity may be risk factors for vitamin D deficiency.

Vitamin D has been known to be involved in innate immunity against viruses and viral diseases like swine flu or H1N1.

David Liu