Investigating Vitamin D PDF Print E-mail
User Rating: / 31
Written by Dr. John Douillard   

New Understandings Unlock The Secrets Of This Elusive Hormone

History of Vitamin D Deficiency
Vitamin D deficiency disease, also known as Rickets, was reported as far back as the 1600s as a bone softening disease. It was originally treated with cod liver oil in the 1800s but it wasn’t until the 1930s that Vitamin D deficiency was identified as the cause. However, Vitamin D is not really a vitamin, but a hormone. In fact, Vitamin D in the active form, known as D3 or calcitriol, is now understood to be the most potent steroid hormone in the human body.

At optimal levels it may be responsible for preventing many modern diseases. About ten years ago researchers discovered that people who live in climates where natural sun exposure was the greatest had lower rates of chronic disease. Studies show that up to 61% of Americans in northern climates are Vitamin D deficient, and during the winter months up to 87% are deficient(1)(2).

Surprising Health Findings
For the past eighty years it was believed that Vitamin D3 was only important to the body for regulating calcium and protecting the bones. This is true if your Vitamin D3 levels are below 50ng/ml. However, new research reported by the Vitamin D Council has shown that higher levels of Vitamin D can provide even more benefits. For example, when Vitamin D3 levels are between 50-80 ng/ml the excess calcitriol (the steroid hormone form of Vitamin D) heads towards the cells, not the bones. It is this overflow of calcitriol that has created such a worldwide stir about the pervasive health benefits of “optimized” Vitamin D. At lower levels of sun exposure and Vitamin D production, this overflow simply doesn’t happen. The understanding of the role of excess calcitriol in the cells is only now understood and many Vitamin D experts believe this to be the most important health discovery in 100 years.

Vitamin D is technically not a ‘vitamin’,” and is in a class by itself. Its metabolic product, calcitriol, is actually a secosteroid hormone that protects over 2,000 genes (about 10% of the human genome) in the human body from expressing negative traits. This means that if your family has a genetic predisposition for a disease, you may be able to prevent it by optimizing your Vitamin D levels.

Symptoms of Vitamin D Deficiency
Current research has implicated Vitamin D deficiency as a major factor in the pathology of at least seventeen varieties of cancer as well as heart disease, stroke, hypertension/high blood pressure, autoimmune diseases (such as multiple sclerosis), diabetes, depression, obesity, chronic muscle and/or joint pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease and more. New reports from the council have linked Vitamin D deficiency to increased risk of H1N1 (“swine flu”) and autism.

No Sun = No Fun
Fifty thousand years ago humans lived predominately in climates around the equator. Clothing was minimal and sun exposure was constant. As we migrated north, we endured sunless winters, wore more clothes and adapted to living indoors – away from the sun. Today we live, sleep, eat and drive indoors away from the UVB sun rays that trigger our body to produce Vitamin D. In latitudes north of Atlanta (33°N), the UVB (sun rays necessary for Vitamin D production) simply do not exist from November through March which can make these months an emotional endurance event for many. Seasonal affective disorder (SAD), often termed winter depression, is related to low serotonin levels caused by Vitamin D deficiency (2).

According to the US News Report, UVB rays are only available when the UV Index is at 3 or above which doesn’t happen in the winter for most of America - so check the UV Index in your area. It is the UVB rays that convert the cholesterol (7-dehydrocholesterol) in the skin to D3 (cholecalciferol).

D3 versus D2
The D3 form of Vitamin D has the highest absorptive affinity and lower toxicity in the human body compared to the more popular Vitamin D2 (ergocalciferol) (3). For this reason Vitamin D3 will store longer in the fat cells and help us endure a long UVB deficient winter. Vitamin D2, which absorbs into the body 70% less than the Vitamin D3 (4), was thought to be the most active source of Vitamin D supplementation. It is still used to fortify foods such as milk and orange juice and is the main pharmaceutical form of Vitamin D support, although many pharmacies are now switching to Vitamin D3 supplementation.Vitamin D3 is primarily produced as a result of sun exposure but is also found in cod liver oil and some fatty fish.

How to Get Vitamin D3 From the Sun
During the summer months the UVB rays are the strongest between the hours of 10 A.M. through 2 P.M. For most people 10-15 minutes of direct sunlight on unprotected skin during these hours will be enough to manufacture about 10,000 - 20,000 IUs of Vitamin D3. Get just enough sun to turn your skin slightly pink. Darker skinned people will have to get more sun exposure to optimize their Vitamin D levels. It takes about an hour for the cholesterol on the skin to convert to D3 and then to be absorbed. So if you work out or exercise in the sun and then take a quick shower you might be washing off all that precious Vitamin D you just manufactured on your skin. Many animals get their Vitamin D by licking their oily fur which has combined with the UVB rays to make Vitamin D3.

How Your Body Uses Vitamin D3
From the skin, the Vitamin D3 (cholecalciferol) heads to the liver where it is converted to calcidiol (25 hydroxyvitamin D). This is the form that circulates in the blood and is the most accurate form to be measured in a blood test. From here the calcidiol heads to the kidneys where it is converted to calcitriol (1,25-dihydroxy Vitamin D), the potent steroid hormone I mentioned earlier that helps prevent at least 17 cancers and numerous health issues, in addition to protecting over 2000 genes in the body from expressing negative traits. When Vitamin D levels are optimized (between 60 - 70ng/mL), numerous genetic predispositions like diabetes, breast cancer, MS, rheumatoid arthritis and many more simply don’t become expressed.

The Sun’s Benefits Outweigh Risks
Many researchers now believe that the benefits of safe sun exposure outweigh any of the potential risks. The fact is that few people die of skin cancer and many die of sunlight or Vitamin D deficiency. As for melanoma, the deadly form of skin cancer, new theories suggest the cause of melanoma may in fact be a deficiency of sunlight. It seems the real and only health risk coming from the sun is when the skin is burned due to prolonged exposure.

Vitamin D Prevents Risk of H1N1
Vitamin D expert Dr. John Cannell developed a theory that influenza is seasonal because of seasonal variations in sunlight which cause fluctuations in Vitamin D levels(3),(4). Vitamin D activates genes to protect AMP, or antimicrobial peptides, which govern our immune system’s ability to fight viruses like influenza(5). Vitamin D is converted into its potent form in the respiratory cells, boosting respiratory immunity(6). It is now clear beyond doubt that low Vitamin D levels are correlated to increased risk of H1N1 flu and typical influenza(7). Vitamin D also suppresses inflammatory cytokines which are responsible for the pain and misery associated with the flu(8).

While it is clear that the connection of the flu to low levels of Vitamin D exists, the key – according to most researchers – is to get enough Vitamin D to boost the natural immunity against not only the flu but many of the chronic diseases that haunt us.

Toxicity – Fiction or Fact?
With many articles discussing that individual sensitivity issues may exist, it’s important to be aware that Vitamin D toxicity is rare. One study showed that 4,000 IUs per day for several years was completely safe and only after taking 40,000 IUs per day for several years is there a risk of developing toxicity symptoms(5).

That being said, as I review the research, I am not so convinced that we can be casual about the intake of high dosages of Vitamin D supplements. Ideally, I think we should all do our very best to optimize our Vitamin D levels in the summer when the UVB rays are available. There is absolutely no Vitamin D toxicity from the sun because UVA rays break down the excess Vitamin D. Vitamin D is stored in the fat so we do carry much of it into the winter months if we optimize the summer’s UVB rays. Unfortunately, most of us work indoors during midday summer hours when the UVB rays are at their peak.

Sunscreen Risks
For the past twenty-five years, sunscreens have only blocked out the skin-protecting UVB rays, but not the UVA rays which are more abundant and penetrate deeper into the skin, making them more harmful than the UVB rays. It was mistakenly thought that the UVB rays were the skin cancer causing rays, so sunscreens were designed with SPF factors that measure the effectiveness of blocking only UVB rays. Twenty years ago SPF ratings were only 10, but today they have risen up to 100 because sunscreens weren’t preventing skin cancer even though the use of sunscreen has increased. Sadly, sunscreens have been blocking the good cancer protecting UVB rays and letting in the skin cancer causing UVA rays for all these years.

How to Optimize Your Vitamin D Levels and Prevent Deficiency
Summer Sun Exposure:

  1. Regularly receive midday sun exposure between 10 A.M. and 2 P.M. in the late spring, summer and early fall, exposing as much of the unprotected skin as possible for 10-15 minutes if your are fair-skinned, longer if you are dark-skinned.
  2. Supplementation: Depending on your sun exposure, I suggest minimal Vitamin D3 supplementation in the summer – perhaps a dose of 1,000 - 3,000 IUs per day.
  3. Test Your Vitamin D Levels: to ensure you have optimized summer sun exposure.

Winter Vitamin D Optimization:

  1. Supplements: Take 5,000 IUs of Vitamin D3 per day for three months, and then take a 25-hydroxyvitamin D test.
  2. In my opinion the goal is to get your Vitamin D levels between 60 and 70 ng/mL and keep them there. Testing is the only way to know for sure that you are maintaining these levels. Test yourself in the fall when the levels are the highest and in March when they are the lowest. With those two numbers, everyone can safely calculate their Vitamin D supplement needs.

Children: Take 2,000 IUs Vitamin D3 per day during the winter.

Dr. John Douillard is an Ayurvedic and chiropractic physician who has taught Ayurveda, natural health, fitness and nutrition internationally for twenty-one years. He is the author of The 3-Season Diet; Body, Mind, and Sport; Perfect Health for Kids, The Encyclopedia of Ayurvedic Massage and three DVDs released by Gaiam on Stress, Detox and Weight Loss. He was the former Director of Player Development for the New Jersey Nets and currently directs the LifeSpa - Ayurvedic Retreat Center in Boulder, CO, where he lives with his wife and six children. Visit the website to sign up for Dr. Douillard’s video newsletter:

Article reprinted by permission.


  1. J Clin Endocrinol Metab. 2002 Nov; 87(11): 4952-6.
  2. AM J Clin Nutr. 2007 Mar; 85(3): 860-8.
  3. Virol J. 2008; 529.
  4. Epidemiol Infect. 2006 Dec; 134(6): 1129-40.
  5. Science News. 2006 Nov 11: 312-3.
  6. J Immunol. 2003 Dec 15; 171(12): 6690-6.
  7. Partonen T. Vitamin D and Serotonin in the Winter, Med Hypotheses. 1998 Sept; 51(3):267-8.
  8. Armas LA, Hollis BW, Heaney RP. Vitamin D2 is much less effective than Vitamin D3 in humans. J Clin Endrinol Metab. 2004;89(11)5387-91.
  9. Trang HM, Cole DE, Rubin LA, et al. Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. Am J Clin Nutr. 1998 Oct;68(4):854-8.
  10. Heaney RP, Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr.2003. Jan 77;(1):204-10.

Dr. John Douillard has a Vitamin D home test kit available for purchase at:

Coral LLC uses coral harvested not from the dwindling reefs on the ocean floor, but from sources that are 10,000 years old and now above the sea mineral deposits. Daily D contains 5,000 units of Vitamin D3 (cholecalciferol) and 100mg of calcium:


Featured Advertisers