Enjoy the Sun! (Review of Vitamin D Benefits)

Review of Vitamin D articles – Megan C Taylor, ND (written while NCNM Student)

Sun Exposure: Not only Beneficial, but Necessary

For many years the effect of vitamin D in cancer prevention has been established. However, due to the multi-factorial nature of tumor development, it has been difficult to absolutely, conclusively, and scientifically demonstrate this to those who are skeptical.

“In the early 1980’s, it was first observed that malignant cells that had a vitamin D receptor (VDR) responded to 1,25(OH)2 D3 with marked inhibition of proliferation and induction of terminal differentiation” (Mol Aspects Med).  Despite these findings, the last 30 years have created a craze more against sun exposure and for daily use of sunblock.  In recent years, there have been myriad studies about sufficient amounts to prevent not only bone disease, but also many common, deadly cancers, “autoimmune diseases, gestational preeclampsia, diabetes type I and II, heart disease, dementia, and infectious diseases” (J Investig Med)… so far.

The new 2011 recommendation for vitamin D is as follows, “For vitamin D (assuming minimal sun exposure) the EAR(Estimated average requirement) is 400 IU/day for ages older than 1 year and the RDA(Recommended dietary allowance) is 600 IU/day for ages 1 to 70, and 800 IU/day for 71 years and older, corresponding to serum 25-hydroxyvitamin D levels of 16 ng/mL (40 nmol/L) for EARs and 20 ng/mL (50 nmol/L) or more for RDAs… Tolerable Upper Intake Level ranges from 1000-4000 IU daily for vitamin D” (J Am Diet Assoc). EAR represents the minimum amount one should take in to avoid symptoms of deficiency.  The RDA represents the amount one should have each day for beneficial effects. Note: Optimal levels of intake may be much higher, if recommended by a physician, and may not be sustained for long periods of time if used therapeutically.

In order to meet these recommendations, a June 2010 study was done by the Memorial Sloan-Kettering Cancer Center in New York to determine the approximate length of exposure needed to attain the EAR. According to the results of the study, “Boston, MA, from April to October, at 12pm EST, an individual with type III skin, with 25.5% of the body surface area exposed, would need to spend 3-8 minutes in the sun to synthesize 400 IU of vitamin D” (J Am Acad Dermatol). The same parameters in Miami, FL only required 3-6 minutes. However, it should be noted that “Vitamin D synthesis occurs faster in individuals with lighter Fitzpatrick skin types” (J Am Acad Dermatol).  Beyond sun exposure, vitamin D can be found in food sources including, “oily fish, such as salmon, mackerel and herring, and liver oils from cod, tuna and shark. Sun dried mushrooms also contain variable amounts of vitamin D” (Mol Aspects Med).

Regarding Sun Baths, Dr. Henry Lindlahr stated in 1919, “We will see that the effects of sunlight cannot be overestimated when we consider that without it life on this planet would be impossible” (Lindlahr, 178). He then cautions light-skinned beginners to air- or sun-bathing to gradually increase exposure until the skin bronzes and can better tolerate the sun without burning. He encourages facilities for a cool or cold shower so that one (sun bath) “can be taken in warm weather while exposed to the air and sun. Allow the body to dry in the sun and air. The alternating influences of air, sunlight and water are as beneficial to the human body as to plant and animal life” (Lindlahr, 179).

One of the main functions of vitamin D is regulation of calcium absorption. Calcium, crucial to bone health – an increasing concern to the aging and menopausal female population – is dependent on vitamin D for proper absorption and utilization. Beyond bone health, Vitamin D “also plays a role in reducing risk of many chronic diseases including type I diabetes, multiple sclerosis, rheumatoid arthritis, deadly cancers, heart disease and infectious diseases” (Mol Aspects Med).  Regarding the “deadly cancers”: “There is strong epidemiological data that living at higher latitudes and being at higher risk of vitamin D deficiency or being vitamin D deficient increases risk of not only developing but dying of deadly cancers including cancers of the colon, prostate, breast, and esophagus among other cancers”(Mol Aspects Med). In one study, “mice who were vitamin D deficient and received a mouse colon tumor subcutaneously had a more aggressive tumor growth of as much as 40% compared to mice that were receiving an adequate amount of dietary vitamin D”(Mol Aspects Med).  The same article discussed the role of vitamin D in autoimmune disease and found that,

“There is a latitudinal association risk of many autoimmune diseases including multiple sclerosis, rheumatoid arthritis, Crohn’s disease and type I diabetes… 10,366 children in Finland who received on average 2,000 IU of vitamin D/day in the 1960’s and followed for 31 years had a 78% reduced risk of developing type I diabetes. Living above 35’ latitude for the first 10 years of life increased risk of developing multiple sclerosis by 100%. Women who ingested more than 400 IU/day of vitamin D had a 42% reduced risk of developing MS and a 40% reduced risk of developing rheumatoid arthritis and osteoarthritis.”

Beyond the risks of all the aforementioned cancers and conditions if insufficient levels are present, vitamin D has a significant role in general health and maintenance of the immune system. This is especially important in the fall and winter months which present the greatest annual infectious threats.  Interestingly, these are also the months that provide the least sunlight/ultraviolet B radiation for natural conversion of cholesterol to vitamin D in the skin.  It is for this reason that cholesterol levels will appear slightly lower toward the end of the summer and higher at the end of winter, provided significant changes in seasons are present. Supplementation of vitamin D3 (1,000-2,000 IU/day is typical) during these months may be beneficial to ensure proper immune function as well as mood stabilization. Note: Most supplemental vitamin D3 is sourced from Lanolin from lamb’s wool. This can be an issue if there is an allergy or sensitivity to wool or if the patient is vegan. (Vegan D3: http://www.vitashine-d3.com/ sourced from lichen.)

Some racial differences have also been noted. In those with naturally darker skin, the increased melanin serves to protect the skin from damaging ultraviolet radiation which is present in large amounts in areas of the world much closer to the equator.  When darker skinned individuals live somewhere that doesn’t have intense sunlight most of the year, that same melanin “protects” from UVB radiation that converts the cholesterol into vitamin D in the skin. For those with darker skin who live in these less sunny areas, supplementation may be required to maintain healthy levels. These individuals also tend to have higher cholesterol levels, in part so that there is a greater likelihood of any sun exposure they do get readily converting to much needed vitamin D.

Regarding the fairly recent fervor surrounding tanning beds, or artificial sources of UVB, one study showed “One tanning bed session had significant, but modest impact on the level of 25-OHD during 7 days after exposure to UVB” (Endocrine). Although, like sun exposure, some benefits are shown with mild to moderate use of tanning beds (up to 2-3 times per week), and risks of excessive exposure have also proven true. A team at Nanjing Medical University in China has demonstrated, through a study of almost 73,500 female nurses over 20 years, that there is significant evidence “for a dose-response relationship between tanning bed use and the risk of skin cancers, especially BCC, and the association is stronger for patients with a younger age at exposure” (J Clin Oncol).

Sun exposure has the potential risks of sunburn, Actinic Keratosis, Squamous Cell Carcinoma, Basal Cell Carcinoma, and Melanoma (the only reasonably potentially invasive skin cancer) in a person of normal physiology who is not on any photosensitizing medications. However, these are (with the exception of melanoma) local, relatively non-invasive, and easily treated if treatment is not dramatically delayed. The potential results of insufficient exposure as well as benefits of exposure well outweigh the risks of being in the sun unprotected for a reasonable amount of time.

There are minor precautions one can take to minimize any risks of solar radiation. Precautions, such as sunblock application, should be taken with: Greater than 20 minutes continuous exposure to intense (11am-2pm) sunlight, and greater than 30-40 minutes exposure to low to medium intensity sunlight, especially combined with a family history of one or more of the above listed lesions, or with light skin, especially with multiple nevi present.  If living in an area with more sunlight (southern United States, or closer to the equator), regular full body skin checks should be performed every six months by a physician or loved one who can help keep a watchful eye on any suspicious lesions.  If nevi or benign lesions are present, the patient should be aware of signs of invasive or malignant changes such as color or pattern change, itching, pain, redness, new formation of nodules, etc.

For light-skinned people not living near the equator or in consistently sunny areas of the world, daily sunblock use (especially in winter months) is not necessary, and may actually increase the risk of other cancers and diseases by preventing beneficial exposure to ultraviolet rays.  Other precautions can, and should, be taken if concerned about the oxidizing effects of sunlight, such as increasing antioxidant consumption from deeply colored fruits and vegetables, especially dark berries, green tea, vitamins C & E, selenium, and glutathione.

Please enjoy responsibly!



-Endocrine. 2012 Mar 6 [Epub ahead of print]. Changes in serum 25-hydroxyvitamin D and cholecalciferol after one whole-body exposure in a commercial tanning bed: a randomized study. Langdahl et al. Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark.

-J Am Acad Dermatol. 2010 Jun; 62(6):929.e1-9. Epub 2010 Apr 3. Estimated equivalency of vitamin D production from natural sun exposure versus oral vitamin D supplementation across seasons at two US latitudes.

-J Am Diet Assoc. 2011 Apr; 111(4):524-7. The 2011 dietary reference intakes for calcium and vitamin d: what dietetics practitioners need to know.

J Clin Oncol. 2012 Feb 27. [Epub ahead of print]. Use of Tanning Beds and Incidence of Skin Cancer. Zhang et al. Cancer center, Nanjing Medical University, Nanjing, China.

-J Investig Med. 2011 Mar 16. [Epub ahead of print]. Vitamin D: A D-Lightful Solution for Health.

-Lindlahr, MD, Henry. Practice of Natural Therapeutics, Vol. 2. 5th Ed. Chicago: Lindlahr Publishing, 1919. 179.

-Mol Aspects Med. 2008 December; 29(6): 361-368. Doi:10.1016/j.mam.2008.08.008. The Vitamin D Deficiency Pandemic and Consequences for Nonskeletal Health: Mechanisms of Action.

admin posted at 2014-11-24 Category: Health Information

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