Fighting Winter Colds with Vitamin D?

By: Sara Hopkins, student at the National College of Natural Medicine (NCNM)

As if we Portlander’s needed another reason to get outside when the sun is shining, it turns out that Vitamin D partially derived from sunlight can actually help us fight off germs! We’ve known for quite some time that Vitamin D is necessary for helping the body use calcium to build strong bones, but researchers have found that Vitamin D also helps in creating small proteins called cathelicidins that are capable of killing invading microbes.

How does my body do this?

Our skin provides the first line of defense against germs that contribute to illness such as the common cold. The skin forms a dry protective layer capable of making these small, microbe-killing proteins. However, cathelicidins don’t just go around killing everything we encounter from the outside world. Just like army troops have to be given the order to fight, these defenders of the immune system have to be activated first.

Our skin cells act like a surveillance crew, always on the lookout for certain patterns that we recognize as being harmful. When those harmful patterns are detected, the skin cell can produce the active form of Vitamin D. Vitamin D acts like an army general, finally giving our cathelicidins the order to fight!

Where do I get Vitamin D from?

Food:  Vitamin D is naturally occurring in the skin of fatty fish such as salmon, fish liver oils, and eggs from hens that have been fed Vitamin D. In the United States cow’s milk, infant formula, orange juice, and cereals are often fortified with Vitamin D as well.

Supplements:  Most Vitamin D supplements are available without a prescription. You can find Vitamin D in multivitamins, some calcium supplements, or as single ingredient supplements. The amount of Vitamin D per dose generally ranges from 400-2,000 IU.

Sunlight with UVB:  Sunlight with UVB rays is able to produce Vitamin D in the skin. There are several factors that can affect the amount of sunlight that is necessary to get adequate Vitamin D such as how light or dark your skin is, where you live, what time of day it is, and your general health status.

Unfortunately, for those of us in Portland (and other locations above 40 degrees of latitude), there isn’t enough UVB to produce Vitamin D from about November to early-March. While some researchers say that as little as 5-15 minutes a day of sunlight to the hands, face, and arms during spring, summer, and fall is enough to provide storage Vitamin D for the winter, many researchers still recommend supplementation to ensure adequate intake.

How much Vitamin D do I need?

According to the National Institute of Health Office of Dietary Supplements, the following are considered adequate intakes for Vitamin D:

Age	Children	Men	Women	Pregnancy	Lactation
0-13 year	5 mcg (200 IU)
14-50 years		5 mcg (200 IU)	5 mcg (200 IU)	5 mcg (200 IU)	5 mcg (200 IU)
51-70 years		10 mcg (400 IU)	10 mg (400 IU)
71+ years		15 mcg (600 IU)	15 mcg (600 IU)

Many researchers believe these levels are still too low to maintain adequate levels of Vitamin D in the body necessary for healthy bones, and as we now know, healthy immune function. Research from supplementation studies also recommend different intakes of 800-1,000 IU per day for adults living in temperate latitudes like Portland to achieve optimal Vitamin D levels.

So to fight off those winter colds, reach for the Vitamin D and give thanks to Mother Earth for her sweet sunshine! And don’t forget to consult your physician before you begin any new form of vitamin therapy!

FOR MORE INFORMATION CHECK OUT THE FOLLOWING LINKS:
The Linus Pauling Institute

NIH Office of Dietary Supplements