Vitamin D deficiency is a silent condition that affects people of all ages.

Mayuri Bhakta, FNP-BC
Medcor Provider

Vitamin D deficiency is a silent condition that affects people of all ages. Vitamin D deficiency can cause feelings of tiredness, weakness, brittle bones, and even stunted growth in children.1

Vitamin D deficiency is a silent condition that affects people of all ages.

What is Vitamin D?

Vitamin D is a nutrient that helps your body absorb calcium. Vitamin D and calcium work together to keep your bones strong and healthy.2 Vitamin D also plays a role in your body’s system of bone formation by helping to keep your parathyroid hormone in check. The parathyroid hormone helps your body release calcium from your bones. If your parathyroid hormone is not regulated, your bones can release too much calcium and become brittle and weak.3 Vitamin D may also help keep your immune system healthy so that your body can effectively fight off infection.4 Vitamin D deficiency occurs when your vitamin D levels get too low.

What causes Vitamin D Deficiency?

  • Lack of sun exposure can lead to low levels of vitamin D. Your body uses UVB rays from sunlight exposure to produce vitamin D in the body. The amount of UV light you can get depends on the time of day, season, weather, and where you live.5  
  • Kidney and liver diseases can decrease your body’s ability to process vitamin D, resulting in low levels.
  • Intestinal diseases (Celiac disease, Crohn’s disease, ulcerative colitis etc.) or gastric bypass surgery can prevent the absorption of vitamin D.
  • Lack of vitamin-D rich foods in your diet can be a risk factor for developing vitamin D deficiency. Fatty fish (such swordfish, sardines, sockeye salmon, and tuna), egg yolks, and liver meat are naturally rich in vitamin D. Since there are only a limited number of foods naturally containing vitamin D, many foods are fortified with vitamin D. Examples of foods fortified with vitamin D include milk, yogurt, cereal, breads, and orange juice. It is important to read labels to see if and how much vitamin D has been added to your food.6
  • Human breastmilk contains very low levels of vitamin D. Exclusively breastfeeding your infant can put your infant at increased risk of developing a vitamin D deficiency. Your child’s pediatrician may recommend that you give your child a vitamin D supplement.7
  • Individuals with darker skin color may require more sun exposure to produce vitamin D and may be at higher risk of developing vitamin D deficiency.8

What happens if my vitamin D levels are too low?

Low vitamin D levels can cause symptoms of tiredness, muscle aches, and bone pain. Low vitamin D levels put children at risk for rickets. Rickets is a disorder that can cause stunted growth, bone and muscle pain, and bowed legs.9 Older children and adults with the deficiency are at risk for osteomalacia, which leads to softening of the bones and increased risk of fractures.10 Because vitamin D helps play a role in keeping your immune system strong, low levels can prevent your body from fighting off infection and cause you to get sick more often.11

How do I know if my vitamin D level is low?

Your healthcare provider can order a blood test to determine whether or not your vitamin D levels are normal.

How can I treat vitamin D deficiency?

Eating a well-balanced diet with a variety of foods may help prevent deficiencies. Because of the limited dietary sources of vitamin D, your provider may recommend that you take a vitamin D supplement. Your recommended dose will depend on your blood test results.

There is debate regarding the appropriate vitamin D blood levels, daily requirements, and recommended supplementation of vitamin D. Depending on the organization, there is variability in the recommended daily intake of vitamin D. For adults, the daily vitamin recommendations vary between 600 IU/day to 1000 IU/day, depending on factors like age, race, medical conditions, and pregnancy status.

It is best practice to check with your healthcare provider to see what dose is best for you.

This article is not intended to diagnose or treat any condition or to give medical advice. Always consult your primary care provider for healthcare instructions. External links are provided as references and do not indicate an endorsement by Medcor. External links are subject to other sites’ terms of use and privacy policies.


[1] Vin Tangpricha and Natasha B. Khazai, “Vitamin D Deficiency and Related Disorders,” Medscape, updated October 22, 2018, https://emedicine.medscape.com/article/128762-overview

[2] Bess Dawson-Hughes, “Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment,” UptoDate, updated May 13, 2019.

[3] Ibid.

[4] Daniel D. Bikle, “Vitamin D Metabolism, Mechanism of Action, and Clinical Applications,” ScienceDirect 21,no. 3 (2014): 319-329. doi:10.1016/j.chembiol.2013.12.016

[5] Vin Tangpricha and Natasha B. Khazai, “Vitamin D Deficiency and Related Disorders.”

[6] Ibid.

[7] Centers for Disease Control and Prevention, “Vitamin D,” https://www.cdc.gov/nutrition/infantandtoddlernutrition/vitamins-minerals/vitamin-d.html

[8] Bess Dawson-Hughes, “Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment.”

[9] Madhusmita Misra, “Vitamin D insufficiency and deficiency in children and adolescents,”UptoDate, updated August 24, 2018.

[10] Bess Dawson-Hughes, “Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment.”

[11] Daniel D. Bikle, “Vitamin D Metabolism, Mechanism of Action, and Clinical Applications.”