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Vitamin D in Health and Disease

December 2, 2011

By Paul D. Tortland, DO

Vitamin D is an important vitamin, right?  Wrong!

Sorry, it’s a trick question. Contrary to popular belief, vitamin D is not a vitamin. It’s actually a hormone. Specifically, vitamin D is a secosteroid. Derived from cholesterol, vitamin D is formed naturally in the body by the conversion of 17-dehydrocholesterol in the cell membrane upon exposure of the skin to solar UVB radiation to produce pre-vitamin D3, which then rapidly gets converted to vitamin D3.

Steroids are proteins that trigger or signal the cell to perform certain tasks, such as synthesizing other molecules. As a hormone, D is directly or indirectly involved in the expression of over 1000 genes in the body. Many tissues in the body possess signaling molecules only in virtual form; they are encoded in the DNA. These molecules are then synthesized only on demand when signaled.

Vitamin D is one of the keys that opens the DNA “library” so the cell can manufacture the necessary proteins and molecules. Without adequate D, the ability of the cell to respond adequately to physiologic and pathologic stimuli is impaired. Vitamin D receptors are found in the brain, prostate, breast, colon, muscle and bone tissues as well as in immune cells.

Vitamin D Deficiency

Some researchers consider Vitamin D deficiency to be an epidemic. An estimated one billion people worldwide have either insufficient or deficient levels. It is considered the most widespread deficiency condition in developed nations. In the United States, at least 36% of otherwise healthy Americans are deficient, and over 70% of pregnant and breast-feeding women are deficient, even though they take prenatal vitamins with D!  Among postmenopausal women taking osteoporosis medication, over 50% are deficient. And 40-100% of the elderly are deficient.

Actions of Vitamin D

As noted, D is involved in many body functions, and has it implications for a wide range of disease conditions.

Bone Health

The most common role of D involves bone health. Without adequate D, only about 15% of dietary calcium is absorbed. Compared to calcium use alone or calcium with only small amounts of D, adequate amounts of D lead to as much as a 58% reduction in risk for osteoporosis and related fractures.

Muscle Strength

Vitamin D is required for maximum muscle function. And D deficiency has been shown to result in muscle weakness. Raising D levels can improve muscle strength and performance speed. Adequate D levels have been shown to reduce the risk of falls in the elderly by as much as 72%.


There is a growing link between D and cancer. Persons with D levels below 20 ng/ml are at 30-50% greater risk of Hodgkin’s, colon, pancreatic, prostate, ovarian and breast cancers. In the famous Women’s Health Initiative study, women with D levels of 12 ng/ml had a 253% increased risk of colorectal cancer within 8 years. One study estimated that colon and breast cancer in North America could be reduced by 30-50% by raising lifelong D levels to at least 40 ng/ml.


D supplementation has been shown to reduce the risk of developing insulin-dependent diabetes (Type 1) in children. In one study, over 10,000 children in Finland were given 2000 IU a day of D for the first year of life only. Their risk of developing Type 1 diabetes over the next 31 years was decreased by 80%!

Cardiovascular Disease

Low vitamin D level is an independent risk factor for heart attacks. In a 2008 study, men with D levels greater than 30 ng/ml had a 50% reduced risk for experiencing a heart attack. Vitamin D also has a positive influence on blood pressure, and it helps reduce vascular calcification and inflammation. Those living farther north (less sun exposure and lower D levels) are at increased risk for cardiovascular disease and high blood pressure. In a 1998 study of patients with high blood pressure, subjects were exposed to ultraviolet-B sun rays three times a week for 3 months. Vitamin D levels went up by 180% and blood pressure normalized.


In a 2009 study, 100 patients with Fibromyalgia (FM) were given enough D to raise their blood levels to 50 ng/ml. After 6 months there were dramatic improvements in chronic fatigue, restless legs, anxiety, depression, muscle spasm, tingling, and concentration.

Infections, Flu & the Common Cold

Vitamin D plays an important role in mustering your immune defenses against infectious disease such as the flu and common cold. A March 2010 study published in the journal Nature Immunology explained this link.

T cells, which are a type of white blood cell known as lymphocytes, play a central role in fighting infection. According to the study, “When a T cell is exposed to a foreign pathogen; it extends a signaling device or ‘antenna’ known as a vitamin D receptor, with which it searches for vitamin D. This means the T cell must have vitamin D or activation of the cell will cease. If the T cells cannot find enough vitamin D in the blood, they won’t even begin to mobilize.”

In other words, low vitamin D levels hinder your natural disease-fighting mechanisms. Vitamin D works by increasing your body’s production of up to 300 different antimicrobial proteins that are actually far more effective than any synthetic antibiotic or antiviral medication. And D does this at a fraction of the cost and with virtually no risks, toxicity, or side effects. A recent study of over 19,000 Americans found that those with the lowest blood vitamin D levels reported having significantly more recent colds or cases of the flu.

Furthermore, while adequate D levels can help reduce the chances of getting the flu, it can help treat it also. If you are coming down with flu-like symptoms and have not been on vitamin D you can take doses of 50,000 units a day for three days to treat the acute infection.

Sources of D & D Treatment

The best source of D is exposure to the sun’s UVB rays. 10-20 minutes of intense sun exposure to the arms and legs twice a week is adequate for ideal levels. It is impossible to get overdose levels of D obtained naturally—the body will break down and excrete the excess. However, concerns over skin cancer limit the applicability of this method.

Oral supplementation of D is the most practical. The best form of D is D3. This is the naturally occurring and metabolically active form. However, virtually all prescription D, and the D in fortified foods (such as milk and OJ), is D2. D2 has a shorter half-life, binds more poorly to proteins, and converts to the metabolically active form 500 times slower than D3. Therefore, foods fortified with D are relatively poor and inefficient sources of D. If you are taking D3 supplements, and your blood levels do not go up, try a different brand of supplement first before increasing the dose. There is a huge variation in the quality of supplements.

The “normal” lab range for D3 is 30-100 ng/ml. However, ideal levels of D3 are between 50-80 ng/ml. While 2,000-4,000 IU of D3 daily will be adequate for most people, it is important to measure your levels of D, both to insure proper treatment and to prevent overdose. Doses as high as 10,000 IU/day may be needed. Also, you may need to adjust your dose seasonally, increasing it in winter months (less sun exposure) and decreasing it in the summer. Levels should be checked every 6-8 weeks until stable, then once every 6-12 months.

Submitted by Paul Tortland, D.O. of Valley Sports Physicians and Orthopedic Medicine. For more information, call (860) 675-0357 or visit

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