Vitamin D for the FLU
Vitamin D for Influenza
To Your Health
October, 2010 (Vol. 04, Issue 10)
Vitamin D for Influenza
By Dr. James Meschino
Another flu season is here; what's your strategy this year? In 2009, many
chose the vaccine route, particularly with the "swine flu" (H1N1) making
front-page news on a near-daily basis. Whether you choose to get
vaccinated or not, it's important to be aware of a simple, natural way you
can help reduce your risk.
Every year the medical profession and government authorities encourage
citizens in many developed countries to get immunized against the current
form of influenza virus. This year is no different, particularly with the
"dreaded" swine flu still on everyone's minds. While the decision to get
vaccinated is an individual one with both pros and cons, consider that a
natural approach, namely supplementation with specific nutrients such as
vitamin D, can boost immune function and may play an important role in the
prevention of respiratory tract infections.
Why Vitamin D?
In recent years, studies have shown that vitamin D is an important
modulator of immune function. Some authorities suggest it has the
potential to reduce the risk of life-threatening influenzas based on the
initial observation that influenza normally strikes in countries during
the colder (winter) months, when vitamin D production in the skin
declines. This happens because the most generally available source of
vitamin D is sunlight. Reduction in skin production of vitamin D due to
reduced or no exposure to daily sunlight is accompanied by a decline in
blood levels of vitamin D.
Some vitamin D experts suggest adults should supplement with 2,000 IU
vitamin D per day (especially during the winter) as a means to maintain
more optimal vitamin D status in general, strengthen immune function and
help reduce the risk of influenza and its invasion into the lung cavity.
Other experts suggest dark-skinned individuals should supplement with
5,000 IU of vitamin D per day during the winter months to help ensure they
attain blood vitamin D levels (25-hydroxycholecalciferol) at or above 50
ng/ml. (Melanin, the pigment that makes the skin darker, acts as a
sunscreen, reducing vitamin D production in the skin upon exposure to
How Vitamin D Affects Immunity
Most immune cells contain vitamin D receptors which allow vitamin D to
enter the cells and exerts its effects on immune cell behavior. In this
capacity, vitamin D has been shown to dramatically stimulate the
expression of potent antimicrobial peptides. These peptides exist in white
blood cells such as neutrophils, monocytes and natural killer cells, and
the epithelial cells that line the respiratory tract, where they play a
significant role in protecting the lung from infection.
Vitamin D influences both innate and adaptive immunity. The cells of the
innate system recognize and respond to pathogens (infectious agents or
germs) in a generic way, and the adaptive immune cells have the ability to
recognize and remember specific pathogens. They, in turn, generate
immunity by mounting stronger attacks each time the same pathogen is
encountered. In simpler terms, vitamin D appears to make immune cells
better able to fulfill their primary function - defense.
Adaptive immunity involves lymphocytes (a specific type of white blood
cell) that are able to express a vast number of specific antigen receptors
on their cell surface. Should the pathogen be reintroduced at a later
point in time, these receptors are activated and the lymphocytes launch an
assault against the pathogen. In adaptive immunity, all of the offspring
of the activated cells inherit genes, encoding the same receptor
specificity. These cells include the memory B cells and memory T cells
that are the keys to long-lived specific immunity.
Vitamin D receptors are expressed in monocytes and in activated
macrophages, dendritic cells, natural killer cells, and T and B cells.
Activation of these receptors by vitamin D has been shown to increase the
activity of natural killer cells and enhance the phagocytic activity of
macrophages. (Phagocytes are white blood cells that protect the body by,
for lack of a better word, "eating" harmful foreign particles, bacteria,
etc.) Active vitamin D hormone also increases the production of
cathelicidin, an antimicrobial peptide that is produced in macrophages.
The release of cathelicidin is triggered by the presence of bacteria,
viruses and fungi.
All of these influences enable the immune system to work in a highly
efficient manner, reducing risk of infection and reducing severity of
infections should they strike. These immune pathways are also important in
preventing cancer. In fact, higher blood levels of vitamin D are
associated with reduced risk of breast, prostate, colon and other cancers.
Several intervention studies have shown that vitamin D supplementation is
associated with a reduction in cancer incidence of approximately 50
percent and that supplementation of 2,000 IU per day slows the progression
of localized prostate cancer in a high percentage of male subjects.
Vitamin D Deficiency
While optimum vitamin D status seems to protect against influenza and
other conditions, vitamin D deficiency is associated with increased risk
of infections, such as influenza and tuberculosis. In one study,
volunteers inoculated with live attenuated influenza virus were more
likely to develop fever and serological evidence of an immune response in
the winter. Vitamin D deficiency also has been reported to predispose
children to respiratory infections. Ultraviolet radiation (either from
artificial sources or from sunlight) has been shown to reduce the
incidence of viral respiratory infections. The same holds true for cod
liver oil supplementation, which is a rich source of vitamin D.
I believe it is important for health practitioners to establish patients'
baseline vitamin D blood levels. Evidence strongly suggests that a level
above 85 nmol/L is highly protective against osteoporosis, cancer,
multiple sclerosis and various infectious processes. Vitamin D toxicity is
a concern only when blood levels of vitamin D rise above 200 nmol/L.
Recent research indicates that supplementation with 1,400 IU of vitamin D
per day appears to be sufficient to raise vitamin D level to the 85 nmol/L
level in most patients. And at the first sign of flu-like symptoms, one
expert - based on personal experience and that of family members -
suggests supplementing with 2,000 IU of vitamin D per kilogram of body
weight for three consecutive days.
Anyone who's suffered through the flu knows that it's not only potentially
dangerous; it can be downright miserable. Ask your doctor to assess your
current vitamin D status and discuss the value of vitamin D
supplementation, particularly during the flu season. Whatever your
strategy, it won't eliminate your risk altogether, but why not do
everything you can do naturally to protect yourself and your loved ones?
Boosting Immune Function: From A to Z
Vitamin D isn't the only ally in the battle against influenza and other
immune-related conditions. Supplementation with vitamin C, vitamin E,
beta-carotene, selenium and zinc appears to boost immune function (even in
elderly patients) and, in some studies, has reduced the incidence of
respiratory infections. And studies have shown that concurrent
supplementation with certain antioxidants can even enhance the protective
effects of the influenza vaccine. As such, I recommend a high-potency
multivitamin/mineral to virtually all adult patients that contains 1,000
mg of vitamin C, 400 IU of vitamin E (succinate), 100 mcg of selenium,
10,000 IU beta-carotene, 15 mg of zinc and a B-50 complex, among the list
of all vitamins and minerals from "A to Z." Such a multivitamin/mineral
should also include vitamin D, of course, which has received attention in
recent studies for its powerful affect on immune function.
James Meschino, DC, MS, practices in Toronto, Ontario, Canada and is the
author of four nutrition books, including The Meschino Optimal Living
Program and Break the Weight Loss Barrier.