The theory that reduced levels of Vitamin D might lead to an increased likelihood of contracting viral infections – while not proven or universally accepted – has seen a fair amount of support in the medical field over the past few years.
While I don’t actively promote Vitamin D in this column, I have blogged on several flu-related Vitamin D studies over the years, Including:
Although intriguing, these studies have yet to settle the debate over Vitamin D’s benefits in warding off viral infections.
In 2010, the IOM released a 999 page report on Vitamin D (see IOM Report On Vitamin D) finding - that while essential for promoting good bone health - insufficient evidence for its effects on other disease processes exists at this time.
The IOM granted that further studies were warranted, but found that those to date they have yielded conflicting and mixed results.
Which brings us to a new study, published in the May edition of the Journal of Leukocyte Biology that suggests that lower levels of Vitamin D – particularly in the elderly – may lead to autoimmune diseases and viral infections.
What these researchers found was a decrease in serum 25-hydroxy vitamin D in healthy adults as they aged, and a negative correlation between serum 25OHD levels and MFI (mean fluorescence intensity) expression of TLR7 on B cells, T cells, and monocytes.
TLR7 is one of a number of toll-like receptors, which are proteins that play an integral role in the innate (or non-specific) immune system.
Our innate immune system not only fights infections, it also buys time for our Adaptive Immune System to learn to recognize and fight specific pathogens.
First some excerpts from the press release, then a link to the abstract.
New research published in the Journal of Leukocyte Biology suggests that the older population could benefit from vitamin D supplementation in autumn and winter to protect against viral infections
Vitamin D may be known as the sunshine vitamin, but a new research report appearing in the Journal of Leukocyte Biology shows that it is more than that. According to the report, insufficient levels of vitamin D are related to a deficiency in our innate immune defenses that protect us from infections, neoplasias or autoimmune diseases. Since vitamin D levels decrease during autumn and winter when days are shorter and sunlight is relatively weak, this may explain why people are more prone to viral infection during these times. It also suggests that vitamin D supplementation, especially in older populations, could strengthen people's innate immunity against viral infections.
Lorena Alvarez-Rodriguez, Marcos Lopez-Hoyos, Maite Garcia-Unzueta, Jose Antonio Amado, Pedro Muñoz Cacho and Victor Manuel Martinez-Taboada
This study adds incrementally to our knowledge, and suggests a mechanism by which low Vitamin D levels might impair immunity.
Not exactly proof that Vitamin D is protective against viral infections.
But it is another piece of data to consider.