Last Updated on January 31, 2023 by Andre Panagos M.D.

What is vitamin D?

Vitamin D, unlike other vitamins is not a vitamin at all, but a fat-soluble pre-hormone that is primarily made following sun exposure on your skin. It can also be found in some foods, although it is thought that sun exposure is the best way to absorb vitamin D.

What is the role of vitamin D and why is it so important?

Until just a few years ago, vitamin D was simply known as the “bone vitamin.” Recently research has found that it is used in virtually every single cell in the body and we now appreciate its greater spectrum of importance. There is compelling evidence for its vital role in a tremendous number of physiologic functions such as immune function, mineral homeostasis, cardiovascular function, and neurological function. Vitamin D also regulates genes that control cell growth and development and may be important in cancer prevention.

How widespread is vitamin D deficiency?

It is estimated that one billion people worldwide are vitamin D deficient and at least 64% of Americans do not have enough vitamin D which is thought to increase the risk of chronic disease. Deficiency has also been found in desert areas of the world such as the Middle East due to traditional clothing styles and time spent indoors.

Where can vitamin D be found?

Unlike other vitamins which are typically obtained from your diet, the vast majority of the vitamin D your body utilizes is synthesized directly from UVB exposure from the sun, hence its nickname, “the sunshine vitamin”. Vitamin D can also be found in some foods, although vitamin D synthesized from the sun is considered a superior form.

How can I get more vitamin D in my diet?

Some great sources of dietary vitamin D include:

Cod liver oil and oily fish such as salmon and mackerel
Organ meats from organically raised, grass-fed animals
Portobello mushrooms

What are the dangers of vitamin D deficiency?

Nowadays, it is clear that maintaining less than optimal levels of vitamin D can be catastrophic. It opens the door to a host of diseases spanning all organ systems of the body, from cardiovascular disease, diabetes, osteoporosis, dementia to musculoskeletal pain, weakness, inflammatory disorders, cancer, immune dysfunction and autoimmune disorders. Without adequate vitamin D, your tissues cannot operate at their peak capacity so some functions suffer, while others outright fail.

What should my vitamin D level be?

Checking individual vitamin D blood levels is still not standard of care for many physicians, but it is one of the most important health-protecting steps you can take. Vitamin D deficiency requires immediate attention and aggressive vitamin D replacement.

Understanding Your Vitamin D Level

Deficient Blood Levels	Insufficient Blood Levels	Sufficient Blood Levels	Optimal Blood Levels	Toxic Blood Levels
< or = to 20 ng/mL	21-29 ng/mL	At least 30 ng/mL	50-80 ng/mL	> 100 ng/mL

What are risk factors for vitamin D deficiency?

The most significant risk factors for vitamin D deficiency include:

Aging: As we get older, our skin changes which leads to a decreased capacity to synthesize vitamin D in the skin when exposed to the sun’s UVB light rays.
Sunscreen and Clothing: Sunscreen and clothing material are effective barriers in blocking the sun’s rays necessary for vitamin D formation. The proper application of sunscreen with an SPF factor as low as SPF-15 absorbs 99% of UVB rays, reducing the production of vitamin D by 99% (Holick M, et. al. 2008).
Dark-Skin: The pigment in our skin called melanin, is a natural and protective sunscreen and is present in greater quantities the darker your skin. This requires more sun exposure to maintain adequate vitamin D levels.
Latitude: The earth’s ozone layer absorbs a portion of the sun’s UVB radiation. The further you live from the equator, the greater the distance the sun’s rays have to travel and less UVB radiation reaches your skin.
-Obesity: Vitamin D gets deposited and sequestered in body fat stores making it less bioavailable for your body’s tissues.
Inflammatory Bowel Disease and Fat Malabsorption Syndromes: An unhealthy gastrointestinal system impairs absorption of vitamin D found in foods.

What should I do to maintain my vitamin D levels?

There are three routes by which you can successfully correct your vitamin D levels. As with any nutritional deficiency, it is ideal to correct it first through natural means so start by having more fun in the sun!

Ways to Increase Vitamin D levels

Route	Advantage
Increase sun exposure	It is possible to obtain your entire vitamin D requirement via sunlight exposure. Aim for 15-30 minutes of direct sun exposure (arms/legs +/- torso). If you expect to be in the sun for a prolonged period of time, set aside some time in the sun before lathering on the sunscreen. But by all means, protect your face with sunscreen at all times and save yourself the wrinkles!
Increase dietary intake of vitamin D-rich foods	Very few foods naturally contain vitamin D therefore it is important to recognize that it is essentially impossible to satisfy the body’s requirement via dietary sources alone, unless you eat oily fish 3-5 times a week.
Direct ingestion of a vitamin D supplement	The dosage of supplementation1 depends on your current vitamin D status. Start by having your physician check your vitamin D level via a simple blood test before you take a supplement.

ICD-10 code E55. 9 for Vitamin D deficiency

Resources:

Holick, Michael F. “Vitamin D: A D-Lightful Health Perspective.” Nutrition Reviews 66 (2008): S182-194. Print.

Holick MF. Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin Nutr. 79(3) (2004): 362-371. Print

Holick, Michael F. “Vitamin D: The Underappreciated D-lightful Hormone That Is Important for Skeletal and Cellular Health.” Current Opinion in Endocrinology & Diabetes 9.1 (2002): 87-98. Print.

Matsuoka, L. Y., L. Ide, J. Wortsman, J. A. Maclaughlin, and M. F. Holick. “Sunscreens Suppress Cutaneous Vitamin D3 Synthesis.” Journal of Clinical Endocrinology & Metabolism 64.6 (1987): 1165-168. Print.

Zhang, Ran, and Declan P. Naughton. “Vitamin D in Health and Disease: Current Perspectives.” Nutrition Journal 9.1 (2010): 65. Print.