What Is Vitamin D Deficiency?

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Vitamin D is often referred to as the "sunshine vitamin" because it is produced by your body when your skin is exposed to the sun. Since vitamin D helps to keep your bones strong, a deficiency can lead to bone softening and subsequent bone pain and fractures.

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What Does Vitamin D Have to Do With MS?

While vitamin D deficiency is unfortunately very common, the good news is that this health condition can be diagnosed with a simple blood test and treated with supplements.

Vitamin D Deficiency Symptoms

Most people with vitamin D deficiency are asymptomatic. Only with a severe and prolonged deficiency do symptoms arise.

The major role of vitamin D is to absorb calcium and phosphorus from the intestines in order to build and maintain bone mass. With vitamin D deficiency, this cannot occur adequately. With a severe deficiency, bone softening (a condition called osteomalacia in adults and rickets in children) may develop.

With osteomalacia and rickets, a person may experience throbbing bone discomfort and muscle weakness and pain. Osteomalacia also increases a person's chances of developing bone fractures, falling, and experiencing walking problems.

Besides bone and muscle symptoms, fatigue and depression are also associated with vitamin D deficiency.

Causes

Since you need sun exposure to make vitamin D, the most at-risk populations for vitamin D deficiency include anyone who spends a lot of time indoors (the elderly and the homebound, for example) and people with dark skin (as it absorbs less sunlight than lighter skin).

Other populations at risk for vitamin D deficiency include:

  • Those who do not consume enough vitamin D-containing foods (e.g., canned tuna and fortified cow's milk)
  • Those with diseases that affect the absorption of vitamin D in the gut (e.g., celiac disease and Crohn's disease)
  • Those with diseases that affect the metabolism of vitamin D into its active form (e.g., chronic kidney disease or liver disease)
  • Those who are obese (extra fat tissue hides away vitamin D instead of releasing it into the bloodstream)
  • Those who take medications that enhance the breakdown of vitamin D (e.g., anti-seizure medications)

Interesting Associations

Besides its primary function in calcium metabolism, vitamin D may play a role in reducing inflammation and moderating immune function in the body. This may be why research has found links between vitamin D deficiency and various autoimmune diseases like multiple sclerosis, rheumatoid arthritis, and type 1 diabetes.

Heart disease and cancer have also been linked to vitamin D deficiency. In fact, research has shown that more heart attacks occur in the winter (when people go outside less and therefore have lower vitamin D levels), and that people survive cancer better in summer months (when their vitamin D levels are higher).

Diagnosis

If you have one or more risk factors for vitamin D deficiency—for example, if you are obese, or if you have chronic kidney disease or a gut malabsorption syndrome—your healthcare provider should screen you for vitamin D deficiency.

Certain symptoms may also prompt your healthcare provider to test for vitamin D deficiency, such as an increased number of falls, especially if you are elderly.

However, screening for vitamin D deficiency in a person without symptoms is currently not recommended.

A simple blood test called 25-hydroxyvitamin D or 25(OH)D can be used to diagnose vitamin D deficiency.

While there is no definitive consensus about what a normal, healthy vitamin D level is, the Institute of Medicine (IOM) defines it as follows:

  • Normal: 25 (OH)D level greater than 20 ng/mL
  • Insufficient: 25 (OH)D level between 12 to 20 ng/mL
  • Deficient: 25 (OH)D level less than 12 ng/mL

Treatment

The treatment of vitamin D deficiency depends on a number of factors, such as the severity of the deficiency and whether certain underlying health problems exist.

That said, in the vast majority of cases, vitamin D deficiency is treated with a supplement.

Supplements

There are two major forms of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), the latter of which is used in most supplements.

To date, there is no standard regimen for treating vitamin D deficiency. A typical plan, though, may include taking 50,000 international units (IU) of vitamin D2 or D3 by mouth once a week for eight weeks, or 6,000 IU daily followed by a maintenance dose of 1,500 to 2,000 IU of vitamin D3 daily.

Keep in mind that higher doses will be needed to treat people with medical conditions that affect vitamin D absorption in the gut, and those taking medications that affect vitamin D metabolism.

Vitamin D Toxicity

Excess vitamin D may cause symptoms related to high calcium levels in the blood, such as muscle weakness, pain, heart arrhythmias, and kidney stones. This is why it is important to only take a vitamin D supplement as directed by your healthcare provider.

Food

Diet is an additional, although not robust, source of vitamin D, and therefore not usually recommended for treating a deficiency. That said, it can be useful for maintaining a healthy vitamin D level.

Foods that contain vitamin D include:

  • Fatty fish (e.g., salmon and swordfish)
  • Cod liver oil
  • Nuts
  • Cereals and dairy products fortified with vitamin D
  • Cheese
  • Eggs
  • Mushrooms
  • Beef liver

Sunlight

Sunlight is the third source of vitamin D. As with diet, it is not usually recommended as a treatment for vitamin D deficiency. This is because of the increased risk of skin cancer associated with sun exposure.

Prevention

While the amount of vitamin D that a person needs varies based on factors like skin color and sun exposure, general recommendations from the IOM state that individuals ages 1 to 70 should take a supplement containing 600 IU of vitamin D daily. After age 70, a person should take 800 IU of vitamin D daily.

These vitamin D preventive recommendations are for the general population—not for people with a diagnosed vitamin D deficiency. People who are deficient in vitamin D require therapeutic doses of vitamin D.

In addition to or in lieu of taking a supplement, your healthcare provider may recommend that you eat or drink foods that contain vitamin D and/or that you get some sunshine (but not too much).

A Word From Verywell

The treatment of vitamin D deficiency is important for keeping your bones strong, and it may improve the health of other systems and tissues in your body like your immune system and heart.

However, before you make big changes, please talk with your healthcare provider first to decide what the best treatment plan is for you.

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15 Sources
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  1. Nadeem SB, Munim TF, Hussain HF, Hussain DF. Determinants of Vitamin D deficiency in asymptomatic healthy young medical studentsPak J Med Sci. 2018;34(5). doi:10.12669/pjms.345.15668

  2. Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium; Ross AC, Taylor CL, Yaktine AL, et al., editors. Dietary Reference Intakes for Calcium and Vitamin D. Washington (DC): National Academies Press (US); 2011.

  3. Cleveland Clinic. Osteomalacia. Updated August 14, 2018.

  4. Roy S, Sherman A, Monari-Sparks MJ, Schweiker O, Hunter K. Correction of low vitamin D improves fatigue: Effect of correction of low Vitamin D in fatigue study (EViDiF study). N Am J Med Sci. 2014 Aug;6(8):396-402. doi:10.4103/1947-2714.139291

  5. Wong SK, Chin KY, Ima-Nirwana S. Vitamin D and depression: The evidence from an indirect clue to treatment strategy. Curr Drug Targets. 2018;19(8):888-97. doi:10.2174/1389450118666170913161030

  6. Nair R, Maseeh A. Vitamin D: The "sunshine" vitamin. J Pharmacol Pharmacother. 2012;3(2):118-26. doi:10.4103/0976-500X.95506

  7. National Institutes of Health. Office of Dietary Supplements. Vitamin D fact sheet for health professionals. Updated March 26, 2021.

  8. Cleveland Clinic. Vitamin D deficiency. Updated October 16, 2019.

  9. Harrison SR, Li D, Jeffery LE, Raza K, Hewison M. Vitamin D, autoimmune disease and rheumatoid arthritisCalcif Tissue Int. 2020;106(1):58-75. doi:10.1007/s00223-019-00577-2

  10. Fares A. Winter cardiovascular diseases phenomenon. N Am J Med Sci. 2013;5(4):266-79. doi:10.4103/1947-2714.110430

  11. Vuolo L, Di Somma C, Faggiano A, Colao A. Vitamin D and cancerFront Endocrin. 2012;3. doi:/10.3389/fendo.2012.00058

  12. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an endocrine society clinical practice guidelineJ Clin Endocrinol Metab. 2011;96(7):1911-1930. doi:10.1210/jc.2011-0385

  13. US Preventive Services Task Force, Krist AH, Davidson KW, et al. Screening for vitamin D deficiency in adults: US Preventive Services Task Force Recommendation StatementJAMA. 2021;325(14):1436. doi:10.1001/jama.2021.3069

  14. Ross AC et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab. 2011 Jan;96(1):53-8. doi:10.1210/jc.2010-2704

  15. Pilz S, Zittermann A, Trummer C, et al. Vitamin D testing and treatment: a narrative review of current evidence. Endocr Connect. 2019;8(2):R27-R43. doi:10.1530/EC-18-0432