Confronting the Worldwide Epidemic
of Vitamin D Deficiency
by Marc S. Micozzi, MD, PhD, Bethesda Maryland

Introduction
    The term vitamin D actually refers to a pair of biologically inactive precursors of a critical micronutrient. They are vitamin D3, also known as cholecalciferol, and vitamin D2 also known as ergocalciferol. Cholecalciferol (D3) is produced in the skin by a photoreaction on exposure to ultraviolet B light from the sun (wavelength 290 to 320 nanometers). Erogcalciferol (D2) is produced in plants and enters the human diet through consumption of plant sources.

    Once present in the circulation, both D2 and D3 enter the liver and kidneys where they are hydroxylated to form both 25-hydroxyvitamin D and 1, 25 dihydroxyvitamin D. 25-Hydroxyvitamin D is relatively non-active and represents the storage form of vitamin D. By contrast, 1, 25 dihydroxyvitamin D is highly active metabolically and its levels are tightly controlled. Vitamin D has many critical metabolic functions. There has been recent confusion in the literature regarding differences in relative abundance, availability and effects of vitamin D2 vs. D3 which have been reconciled by thoughtful investigation 1.

    The direct connection between sun light and bone metabolism was also established in 1919 when Huldschinsky treated rickets with exposure to a mercury arc lamp. In 1921, Hess and Unger observed that sun exposure cured rickets.

    In the 1920s medicine began to directly appreciate the connection between sunlight and the metabolic activities we now associate with vitamin D. This was also the decade that saw the actual identification and labeling of the many metabolically active constituents we now call vitamins. Vitamin D was discovered in the early 1920s by Windaus who was later awarded the Nobel Prize for his synthesis of vitamin D in the laboratory by replicating the photoactivation process that occurs in the skin.

    In the 1930s the federal government set up an agency to recommend to parents, especially those living in the northeast, that they send their children outside to play and get some sun exposure. Foritification of milk with vitamin D also began at that time. Unfortunately, the last 40 years have actually seen a reversal of some of the sensible public health recommendations regarding adequate Vitamin D and sun exposure (see Vitamin D and Sun Exposure: There Goes the Sun).


Versatility of Vitamin D
    The first major functions of vitamin D to be recognized were (1) enhancement of calcium absorption from the diet through the intestine and (2) mobilization and re-absorption of calcium from bone which represents the major store of calcium (or “calcium bank”) in the body. See Figure 1. Calcium in turn is critical for cellular metabolism and membrane actions, enzymatic reactions, muscle function, skeletal structure and a host of activities needed to sustain life and maintain homeostasis. Since vitamin D has long been recognized for its role in calcium metabolism it has long been used to treat patients with renal failure and bone diseases. It is also important in postmenopausal osteoporosis for the current epidemic of bone fractures in the elderly 2.

    However, in 1979 DeLuca found that vitamin D is actually recognized by every tissue in the body. Every cell has receptors for vitamin D. Since then it has been used to treat hyperproliferative skin diseases such as psoriasis.

    For the immune system, the large white blood cell macrophages activate vitamin D. The activated vitamin D in turn causes macrophages to make a peptide that specifically kills infective agents such as tuberculosis mycobacteria. Vitamin D also has a role in autoimmune diseases such as multiple sclerosis, rheumatoid arthritis and diabetes type 1. Given vitamin D’s long recognized activity in the kidney it was also found to effect renin/angiontensin production in the kidney, the major regulators of blood pressure. There is a direct correlation between higher (more northern) latitudes and higher blood pressure (where both sunlight and vitamin D levels are lower) in both northern and southern hemispheres of the earth. People at high latitudes with high blood pressure experience a return to normal blood pressure levels following UVB light exposure, and restoration of active vitamin D levels, in a tanning bed three times per week for three months (and you thought it only worked if the sunlight was captured on a beach in the Bahamas!). Multiple sclerosis also shows a marked association with higher latitudes worldwide and there may be a similar role for protection by vitamin D.

    Vitamin D is also thought to have an important role in cancer [see Sidebar]. As early as the 1940s it was noted that living at higher latitudes is associated with a higher incidence of several cancers (while only skin cancer specifically has a lower incidence at higher latitudes). Recent epidemiologic observations have continued to bear out this association. A high frequency of sun bathing before age 20 reduced the risk of non-Hodgkin lymphoma 3. And, while sun exposure is related to an increased incidence of malignant melanoma, it was also associated with increased survival from melanoma in a recent study 4. In some of the sunniest spots on earth, both the Australian College of Dermatologists, the Cancer Council of Australia, and the New Zealand Bone and Mineral Society, have concluded that a balance is required between avoiding an increased risk of skin cancer and achieving enough ultraviolet light to maintain adequate vitamin D levels.

    As in all things involving nutrition, achieving a balance is a good goal and guide for optimal health. It was thought that a balanced approach to this problem could be achieved through thoughtful dermatologic screening for skin cancers. Thus, most skin cancers should be detected and treated early since they are by definition visible on the surface of the skin, unlike cancers of other tissues which begin growing hidden and undetected deep inside the body.

Vitamin D and Dermatology: There Goes the Sun
    Many physicians and public health organizations, including the biomedically oriented World Health Organization, have been trying to go one better on Moby Dick’s Captain Ahab, who "would strike the sun" if it insulted him. For 40 years there has been a concerted campaign to make people avoid sun exposure. Since ultraviolet B light from the sun is responsible for the photoactivation of vitamin D in the skin, sun blockers that "protect" the skin also virtually eliminate photoactivation of vitamin D. A sunscreen with SPF of 8 is supposed to absorb 92.5% of UVB while doubling the SPF to 16 absorbs 99%. This essentially shuts down vitamin D production. (It also demonstrates that SPF formulations above 16 have little marginal utility and calls into question the appropriateness of ever-increasing SPF numbers found on the pharmacy shelves)

    A study in Australia which has high levels of sunlight and high rates of skin cancer found 100% of dermatologists to be deficient in vitamin D 5. In fact, most people should go outside in the sun for reasonable periods of time in order to get the many benefits of sunlight [Table 2]. It is always wise to protect the face and head with a hat and sunglasses since less than 10% of UVB light absorption happens above the neck and the face is the most cosmetically sensitive. It is best to expose the entire body in a bathing suit for 10 – 15 minutes at least three times per week. African-Americans require more sun exposure since their natural skin pigmentation accounts for an SPF-equivalent of 8 to 15.

Global D-mensions of D-ficiency
    There is essentially little or no active vitamin D available from regular dietary sources. It is principally found in fish oils, sun-dried mushrooms, and fortified foods like milk and orange juice. However, many countries worldwide forbid the fortification of foods. There is potentially plenty of vitamin D in the food chain because both phytoplankton and zooplankton exposed to sunlight make vitamin D. Wild caught salmon, which feeds on natural food sources, for example, has available vitamin D. However, farmed salmon fed food pellets with little nutritional value have only 10% of the vitamin D of normal fish. The “perfect storm” of photophobia, lack of exposure to sunlight, and insufficiency of available dietary vitamin D has led to a national and worldwide epidemic of vitamin D deficiency.

    It is estimated that at least 30% and as much as 80% of the US population is vitamin D deficient. In the US, at latitudes north of Atlanta, the skin does not make (photo convert) any vitamin D from November through March (essentially outside of “daylight savings time”; so while we shift the clock around, it does not salvage vitamin D synthesis). During this season the angle of the sun in the sky is too low to allow ultraviolet B light to penetrate the atmosphere and it is absorbed by the ozone layer. Even in the late spring, summer and early fall, most vitamin D is made between 10 AM and 3 PM when UVB from the sun penetrates the atmosphere and reaches the earth’s surface.

    It might be expected that vitamin D deficiency would be a problem limited to northern latitudes.

    In Bangor, Maine, in young girls 9 to 11 years old, nearly 50% were deficient at the end of winter and nearly 20% remained deficient at the end of summer. At Boston Children’s Hospital, over 50% of adolescent girls and Black and Hispanic boys were vitamin D deficient year round. In another study in Boston 34% of Whites, 40% of Hispanics and 84% of Black adults over age 50 were found to be deficient 5.

    However, vitamin D deficiency is also a national problem. The US Centers for Disease Control and Prevention completed a national survey at the end of winter and found that nearly 50% of African-American women ages 15 to 49 years were deficient. These represent the critical childbearing years. A growing fetus must receive adequate vitamin D from the mother, especially since breast milk does not provide adequate Vitamin D. A study of pregnant women in Boston found that in 40 mother-infant pairs at the time of labor and delivery, over 75% of mothers and 80% of newborns were deficient. This observation was made despite the fact that pregnant women were instructed to take a prenatal vitamin which included 400 IU vitamin D and to drink two glasses of milk per day 5.

Index of Articles

Site Navigation and Quick Links

Home • Health Club • Site Index • Library • Physicians Only • Checkout
Vitamins • Herbs • Minerals • Amino Acids • Enzymes • Hormones
Homeopathics • Ayurveda • Glandulars • Fatty Acids • Xtra-Cell

Alphabetical Product Index • Health Function Index
Condition Specific Formulas • The Latest Health Research