Most people know that Vitamin D is involved in bone health; but did you know that it is a critical player in the maintenance of overall health, immune response and disease prevention? Research indicates that Vitamin D has a much more encompassing role in the body than we first realized, right down to the cellular level. Vitamin D receptors (VDR) have been identified on numerous types of cells in the entire body.  You can be assured that if there are VDRs on a cell, then Vitamin D has an action in that cell.

The topic of Vitamin D has been abuzz in human Functional Medicine for the last two decades. While most of the Vitamin D research has been in the human realm, recent studies have been done in pets.  As humans and animals acquire their Vitamin D differently, some of the human research can be challenging to extrapolate to the vet world. While humans synthesize most of the Vitamin D in the skin, dog & cats must ingest it. In the wild, Vitamin D-rich diets are easy to find.  It is a fat-soluble vitamin and thus it lives in adipose, or fat, tissue.  Wolves and big cats ingest the fatty tissue, liver, spleen, kidneys, etc. of their prey animals to maintain a healthy level of Vitamin D.  However, when the human population moved inside to work and the pets were put on commercially available kibble & canned diets, it changed the state of Vitamin D acquisition for all of us forever.

Vitamin D plays a critical role in the maintenance of cellular health.  Receptors line immune cells to regulate immune responses within the body.  It literally promotes cellular cancer cell death. In addition, evidence indicates that Vitamin D drives gene transcription, which simply means it helps turn on the genes that promote health and turn off the genes that promote inflammation.  Take a moment to fully realize the implications here.  A strong and adequate immune response means diminished infectious potential. The appropriate activation of genes means that genetic diseases can be modulated; that an unuseful gene that has been expressed can be unexpressed; and proteins that further health and vitality are subsequently produced, while pro inflammatory proteins are down-regulated.  

In numerous studies, insufficient Vitamin D levels have been associated with:

1. Inflammatory Bowel Disease
2. Heart Disease
3. Kidney Disease
4. Cancer **
5. Auto-immune Diseases
6. High Blood Pressure
7. Infectious Diseases
8. Diabetes

**the reviewed studies specifically identified lymphoma, hemangiosarcoma, cutaneous mast cell tumors, sarcomas; however, the mechanisms are the same for all cancers.

Doesn't that about cover most disease....?  Remember, this is what we now know from current research, while more is developing.  The presence of Vitamin D literally decreases inflammation in the body by decreasing inflammatory cytokine release.  

Pop Quiz: What diseases start with inflammation?  

Answer: ALL OF THEM  

What about healthy individuals?  Interestingly enough, a study in healthy dogs found that the majority of domesticated pets had insufficient levels. Another study investigated intact males and females versus neutered pets.  The results suggest that Vitamin D absorption is under some hormonal control, as the neutered pets consistently showed less Vitamin D than intact pets.  A separate study discovered that there may be some breed variations in absorption, as the German Shepherds had a substantially higher Vitamin D levels than Golden Retrievers.  Hmmmmm, interesting that Goldens have low Vitamin D levels and such a high cancer rate....  

(Of course, it is much more complex than this article describes, so consider this a brief teaser.)

You might say, "Well my dog is healthy!"  Remember the old-fashioned mouse trap we often discuss?  A variety of actions must occur as the ball rolls down to the end where the cage eventually drops.  The cage drop represents the disease.  All that occurs prior to it represents the underlying dysfunction that has to develop before the disease is revealed. The time lag from the point of the initiation of dysfunction (ball drop) to just before the obvious clinical symptoms develop (cage drop) is recognized in all spheres of medicine but remains the focus of the holistic mindset.  A recent article regarding Vitamin D in the Journal of Veterinary and Comparative Oncology included the following statement:

"...it is equally recognized that organs compensate for a period of time before decompensating and developing clinical signs of disease."

Sound familiar?  Vitamin D deficiency accrues over time.  By the time you see obvious disease, it has been ongoing for a period of time.  As it is an integral part of a healthy system, wouldn't it be helpful to assess your pet's levels before overt disease occurs? Remember, it is much easier to prevent disease than to treat it.

I am not a practitioner who believes that one size fits all. I believe in the individuality of each patient; and what works for one pet doesn't necessarily works for every pet. I also believe that there are so many disease processes that directly result from insufficient nutrient acquisition caused by insufficient diets, insufficient digestion, or both. If every cell is provided the appropriate nutrients, then its corresponding function will be strong and efficient. Deny any cell the nutrients that it needs to function, and it will fall into dysfunction. Enough cells falling into dysfunction will start to produce symptoms and subsequent disease.

The nature of our pet food industry has created a pandemic of disease. Moving away from fresh, whole foods to a synthesized diet made from the by-products discarded from the human food chain has lessened our pets' nutrient acquisition and subsequently decreased their level of health. It's no mistake that our four-legged furry kiddos have more serious diseases with every subsequent generation. In the veterinary realm, some say that we are better diagnosticians.  I say that we must be because we caused a lot of the disease in believing we know better than Mother Nature.

Vitamin D: Testing & Supplementation

As mentioned in Part I, Vitamin D is a hot topic in the human field for some time. Though we suspected similar issues in the vet world, testing just wasn't available. Supplementing without testing can be quite problematic. Toxic levels of vitamin D can create just as many problems as low vitamin D. It is simply not a vitamin that we throw around without direction.

Now we have an affordable test that is available and it's fairly simple. It's a serum test - that means we draw a fasting blood sample and use the serum for testing. It takes 1 day to prep the sample and then about a week for the results to be returned. With the results comes a report that gives the exact level of 25-hydroxy vitamin D. The pet is started on an appropriate preparation as needed for supplementation, and then the level is rechecked in about two months or so for dosage adjustment. Following this level, a yearly level is performed, unless a life change occurs requiring testing sooner.

Vitamin D is a fat-soluble vitamin, which means that it must be given with the fatty meal and have an adequate bile release to be absorbed. This is problematic in kibble-fed dogs as most all have hypochlorhydria and consequently do not have a healthy bile release. Our patients are healthier than most; and we focus in on restoring the biochemistry of digestion. Thus, initial phases of supplementation of vitamin D will absolutely require follow-up to ensure your pet has the appropriate level of supplementation.

A word of caution: our furry kiddos tend to concentrate excess Vitamin D in the liver, thus appropriate dosing is of paramount importance.  All pets who are supplemented should be tested first to avoid any toxic effects.  All pets have differing needs and one size does NOT fit all.  When appropriately used, Vitamin D supplementation can be life-changing.