Vitamin D and Immune Function

January 14, 2015

Vitamin D and Immune Function

Among many other excellent lectures at our recent annual American Academy of Environmental Medicine conference, we enjoyed a lecture discussing vitamin D and immune function. Ty Vincent, M.D. gave the lecture and summarized some important points which I thought would be good to go over. Most of this probably won’t surprise you as the importance of vitamin D seems to be a common story in the media lately. In fact, over 3,200 studies concerning vitamin D have been published over the last 10 years alone. The funny thing is that it’s not even a vitamin, but rather it is a hormone, and one with many important functions!

At this point it is well accepted among medical experts that being deficient in vitamin D increases the risk of certain cancers, hypertension, allergies, asthma, osteoporosis, and many autoimmune conditions. Deficiency is usually defined as a serum level below 30ng/mL. Unfortunately, vitamin D deficiency is not at all uncommon.

Vitamin D is known to be very important for proper tissue integrity and it is an important regulator of barrier function. Vitamin D increases the production and regulation of T regulatory white blood cells which play a critical role in directing the immune response away from certain antigens. Thereby, vitamin D regulates “tolerance” within the immune system function and is critical for protection against allergy and autoimmune conditions. Vitamin D also protects against excessive and inappropriate inflammation and is critical for the optimal function of certain white blood cells especially monocytes.

Vitamin D also regulates the production of Cathelicidin and Defensin. These are two proteins which play an important role in the immune system response against bacteria, fungi, and viruses. They also promote appropriate wound healing and tissue regeneration. It is also well described that having appropriate vitamin D levels is protective against the development of many cancers including: breast, ovarian, colon, kidney, endometrial, and Non-Hodgkin’s Lymphoma.

I think that it’s easy to determine that vitamin D is critical to keeping the immune system on the right track. So how much vitamin D do we need to take? The answer depends on a few things and points out one of the principles of environmental medicine – the concept of biochemical individuality. In other words, we are all genetically unique. Ideally, we would get just the right amount of sun exposure to generate our vitamin D, but not too much as to increase the risk of skin cancer.

An important source of vitamin D is through certain foods, especially ?sh and dairy. The website lists important sources of vitamin D to include: salmon, sardines, tuna, cow milk, eggs, and even shiitake mushrooms. Cod liver oil also deserves special attention, as it is very high in vitamin D. Some brands have as much as 1360 IU per ounce. It has been my clinical experience that most people do not meet their vitamin D requirement with their diet. However, diet should be taken into consideration when trying to estimate an appropriate vitamin D supplementation dose. The only way to really know a person’s appropriate dose is to measure.


In perfect conditions, it is estimated that between 10 to 15 minutes of direct sun exposure on unprotected skin over 35% of body surface area will produce around 20,000 IU of vitamin D. Even more fascinating is the fact that there is a mechanism which prevents our body from making too much vitamin D with sun exposure. We make the amount we need then it “shuts off”. This mechanism depends on our genetics, our location on the globe, the time of year and amount of exposure. In the tropics, the average person needs about 10 to 15 minutes of direct sun exposure on their torso and/or arms and legs to generate that day’s required amount of vitamin D.

For those of us not lucky enough to be tanning in the tropics, we may have to resort to supplementation. The amount I recommend is the amount required to get the person’s serum D3 level somewhere between 50 to 80ng/mL. In some cases, we may recommend shooting for a higher number around 100ng/mL, but most studies suggest for general health benefits, levels around 50 to 70ng/mL are optimal. The only way to know how much is required to achieve this is to measure through a standard vitamin D level blood test.

Many of you may be wondering about children and what their levels should be as well. Here at the Center, we do not like to ask a child to undergo a traumatic procedure, like a blood draw, unless it is absolutely necessary. So for children, I don’t recommend they have repeated blood draws to determine their vitamin D status. My recommendations for children are:

Up to 1 year of age – Mothers optimize their vitamin D level and breast feed

Ages 1 to 3 – Supplement 1000 IU daily 

Age 3 and up – Supplement 2000 IU daily

My general recommendation for everyone living in the US and Canada is to supplement with an amount of vitamin D3 which will maintain their serum levels between 50 to 80ng/mL through the fall, winter, and spring. Everyone is different. Most adults do best with a 5000 IU daily dose. However, I have patients who only need 2000 IU daily to achieve optimal levels, and I have other patients that need over 15,000 IU daily just to stay in normal serum range. That is why I always recommend that adults supplement with a dose they are comfortable with for a month or two, then have their level checked. It only takes a few measurements to figure out a person’s required dose.

The Vitamin D 25-hydroxy test is available at COEM for $70.

To schedule an appointment for testing, call us at (843) 572-1600

To order any of the Vitamin D products above, or any of the other supplements from COEM, send an e-mail to ORDERS@COEM.COM with the following information.

  • Name
  • Address
  • City/State/Zip
  • Number and exact type of bottle you wish to order
  • Credit Card Information (Type of Card, Card #, Exp. Date, CVV, Name of Card)
  • If you are picking up your order at our office, please let us know as well

Please allow 5-7 business days to process your order.


Yours in health,

William J. Weirs, M.D., F.A.A.E.M.

Center for Occupational & Environmental Medicine

January 14, 2015

Posted in Health Alerts