Vitamin D may reduce risk of severe flu-related illness

This flu season has been unusually active, with the CDC reporting about 19 million illnesses, 250,000 hospitalizations and 10,000 deaths so far; a large University of Surrey study of 36,200 people found that severe vitamin D deficiency was linked to a higher chance of hospitalization for respiratory infections, and hospitalization risk fell modestly as vitamin D levels rose.

This flu season has been more active and severe than expected, in part due to a new flu variant called subclade K. The Centers for Disease Control and Prevention reports roughly 19 million illnesses, 250,000 hospitalizations and 10,000 deaths so far. US flu activity has fallen for three weeks in a row but remains elevated nationally. Researchers and authors of a large study are highlighting vitamin D as a possible factor linked to risk of serious respiratory infections. Key points: - The University of Surrey study analyzed data from 36,200 adults and reported that people with severe vitamin D deficiency (under 15 nmol/L) were about 33% more likely to be hospitalized with a respiratory tract infection than those with sufficient levels. - The study found a reported 4% decrease in hospitalization rate for every 10 nmol/L increase in vitamin D levels. - The results were published in The American Journal of Clinical Nutrition and the authors said the association warrants further study. - The National Institutes of Health recommends daily vitamin D intakes of 600 international units for most adults up to age 70 and 800 international units for those over 70; vitamin D is obtained from sun exposure, some foods, fortified products and supplements. Summary: The report links lower vitamin D levels with a higher risk of hospital admission for respiratory infections during an active flu season, and authors describe the finding as necessitating more research. How these results might affect public health recommendations or clinical practice is undetermined at this time.