by Dr. James Chestnut, D.C.
The issue of Vitamin D3 deficiency as a major causal factor in immune system related illnesses ranging from seasonal cold and flu, to heart disease, to cancer, to atopic and autoimmune disorders has received a lot of attention in the last few years. Clinical journals as well as the mainstream media have been reporting evidence that modern industrialized humans are severely deficient in Vitamin D3 and that this deficiency is a major contributing factor to illness and lack of health and vitality.
What does vitamin D3 do and why is it so important for wellness and prevention?
Before we discuss the evidence regarding vitamin D sufficiency and health and vitamin D deficiency and illness let’s first look at the basic science regarding the importance of vitamin D for human immune function and health. A basic understanding of why vitamin D is a genetic human requirement for wellness and prevention will allow greater understanding of why vitamin D supplementation is required.
The innate immune system is the component of our immune system that is genetically programmed to respond to antigens (viruses, bacteria, fungi, and any other threatening non-self invaders). The innate immune system uses what are termed effectors that are genetically coded to respond to antigens or invaders. The most studied of these effectors are named antimicrobial peptides or AMPs. AMPs not only attack the invaders they also trigger tissue repair and activate the adaptive or acquired immune system (the branch of the immune system that creates antibodies to specific antigens after exposure).
Recent research has shown that vitamin D up-regulates the genetic expression of AMPs in immune cells. Vitamin D also plays an important role in controlling the inflammatory response initiated by specialized immune cells called macrophages. A deficiency of vitamin D means deficient control of inflammation. In the skin vitamin D also activates the immune system against antigens.
“Thus, vitamin D both enhances the local capacity of the epithelium to rapidly produce endogenous antibiotics and, at the same time, dampens certain arms of adaptive immunity, especially those responsible for the signs and symptoms of acute inflammation.” (Cannell et al. 2008 Cod Liver Oil, Vitamin A Toxicity, Frequent Respiratory Infections, and the Vitamin D Deficiency Epidemic. Annals of Otology, Rhinology & Laryngology 117 (11): 864-870).
Can Vitamin D deficiency lead to serious illness?
Let’s now do a quick overview of some of the research showing that vitamin D deficiency can lead to serious illnesses. The evidence that vitamin D deficiency is related to seasonal respiratory illnesses such as cold and flu and that vitamin D sufficiency can both prevent and help to recover from these illnesses is extremely convincing.
The role of vitamin D deficiency in other serious illnesses is also being reported. “As Holick’s New England Journal of Medicine review stressed, the litany of vitamin D deficiency diseases is now legion. Evidence even suggests that vitamin D is involved in the triple current childhood epidemic of autism, asthma, and autoimmune diabetes. Not only do tenable mechanisms of action exist to explain vitamin D’s role in all three, but epidemiological evidence suggesting a vitamin D connection to these devastating diseases is growing.” (Cannell et al. 2008 Cod Liver Oil, Vitamin A Toxicity, Frequent Respiratory Infections, and the Vitamin D Deficiency Epidemic. Annals of Otology, Rhinology & Laryngology 117 (11): 864-870)
“Improving calcium and vitamin D nutritional status substantially reduces all-cancer risk in postmenopausal women.” (Lappe et al. 2007 Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J of Clin, Nutr. 85 (6): 1586-1591).
“Vitamin D is an inhibitor of the renin-angiotensin system and has anti-inflammatory and anticoagulant properties.” “Low serum 25 (OH) D levels are associated with a higher prevalence of Peripheral Arterial Disease. Several mechanisms have been invoked in the literature to support a potential anti-atherosclerotic activity of vitamin D.” (Melamed et al. 2008 Serum 25-Hydroxyvitamin D Levels and the Prevalence of Peripheral Arterial Disease. Thrombosis and Vascular Biology 28: 1179-1185)
There are literally thousands of peer-reviewed scientific articles establishing vitamin D deficiency as a significant causal factor in serious illnesses. At this point we can confidently state that having sufficient levels of vitamin D is essential for both wellness and prevention.
What are the human daily vitamin D requirements?
What we next need to know is whether or not we can attain sufficient vitamin D levels without supplementation. To answer this question we must first know how much vitamin D humans require and then we must learn what the natural, available sources of vitamin D are. Let’s start with the human daily requirements.
According to Dr. Robert Heaney humans utilize approximately 4000 IUs of vitamin D3 per day. (Heaney et al. 2003 Human serum 25 hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am. J Clin. Nutr. 77: 204-210). Dr. John Cannell MD, the Executive Director of the Vitamin D council stated in a recent Vitamin D Council on-line newsletter http:// www.vitamindcouncil.org/vitaminDToxicity.shtml entitled ‘The Truth About Vitamin D Toxicity’ that there is no evidence anywhere in the published literature that even 10,000 IUs per day of vitamin D is toxic to humans and that human toxicity does likely not occur until over 40,000 IUs of daily consumption. “Vieth reports human toxicity probably begins to occur after chronic daily consumption of approximately 40,000 IU/day (100 of the 400 IU capsules).” He goes on to state that “Physician ignorance about vitamin D toxicity is widespread” and concludes by stating that “In fact, living in America today while worrying about vitamin D toxicity is like dying of thirst in the desert while worrying about drowning.” In other words any danger associated with vitamin D is from deficiency NOT toxicity.
The Food and Nutrition Board of the US Institute of Medicine has set the tolerable upper intake level (TUIL) for vitamin D at 2000 IU per day for adults. As you can see above many vitamin D experts disagree with this low setting and state that human adults can require supplementation with up to 4000 IUs per day in the winter months. With all this in mind it appears that it would be prudent to ensure a minimal daily intake of 1000 IUs of vitamin D3 for children, 2000 IUs for adults, and 4000 IUs for pregnant and lactating women who have not previously been sufficient. A pregnant or lactating woman who has maintained sufficient vitamin D levels for years prior to pregnancy will likely not require an increase in daily intake. It would also be prudent to have vitamin D levels tested.
What are the sources of vitamin D? How do we get sufficient amounts?
The answer is SUNLIGHT. In order to get the daily requirement of vitamin D from sunlight you would need to have direct summer month sun exposure on your arms and legs for a minimum of 10-15 minutes per day. This is why vitamin D deficiency is so common in non-tropical climates, especially in the winter months. Of course in the industrial nations neither the climate nor the season are accurate determinants of the amount of sun exposure because most people spend the majority of their time inside or covered up when outside.
So, if you are not getting a minimum of 15 minutes per day of direct summer sunlight on bare arms and legs (without sunscreen) then you need another source of vitamin D. What are the other available sources of vitamin D you ask? Great question!
The simple fact is that humans were never meant to get their vitamin D from food. Genetically humans are designed to get vitamin D from sunlight. As we have outlined above this is simply not a realistic option for most humans living and working indoors or who live in areas where sunlight levels change with the seasons. It should be noted here that humans with pigmented skin (non-caucasians) require significantly more sun exposure to achieve sufficient vitamin D levels. This means these people are at an even greater risk for illnesses caused by vitamin D deficiency.
As humans migrated away from the equator we had to devise ways of replacing the sun as a source of vitamin D. In other words, in order to survive non equatorial climates humans had to find a source of vitamin D other than sunlight. Over thousands of years of experimentation virtually every human culture learned that the best way to stay sufficient in vitamin D in environments with reduced sun exposure was to consume marine animal liver or liver oil. Cod liver oil is probably the best known and widely recognized as the best source of dietary vitamin D3 for humans. For centuries humans have used cod liver oil as a safe and effective way to achieve sufficient vitamin D levels in the absence of sun exposure.