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If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
Vitamin D, or the “sunshine vitamin,” is essential for your health—unfortunately, many people don’t get enough of it. You may notice vitamin D deficiency signs and symptoms more in the winter months, especially if you live far from the equator. Then again, you may not—signs of vitamin D deficiency can be subtle. Read on to learn more about what happens when you don’t get enough vitamin D.
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What is vitamin D?
Often called the “sunshine vitamin,” vitamin D is needed for many different body systems. Unlike other vitamins, vitamin D is not a true vitamin—it is actually a prohormone. Vitamin D, or calcifediol, converts into a hormone in your body. While it primarily functions to improve calcium absorption and create strong bones, you have vitamin D receptors on cells all over your body. As a result, many clinical trials are looking into the role of vitamin D in heart disease, immune system health, muscle strength, among other benefits.
What causes vitamin D deficiency?
Over 41% of adults in the United States don’t get enough vitamin D—this is especially true if you have darker skin. African Americans and other people of color have a high risk (around 70–80%) of lower vitamin D levels (Forrest, 2011).
Why is this? Your body uses the ultraviolet (UV) light from the sun to convert specific cholesterol molecules to make most of the vitamin D your body needs. If you have darker skin, less UV light gets into cells, leading to low vitamin D levels (Sizar, 2020).
Another cause of vitamin D deficiency is that people don’t spend enough time in the sun. The rise in concern over skin cancer has diminished the already small amount of time people spend in the sun. Coupled with a shift to more office work, we may not be getting enough sun for adequate vitamin D production (Sizar, 2020).
Vitamin D deficiency does not always come from a lack of sunlight. It can also be a result of a poor diet. Eating fatty fish and eggs, vitamin D fortified milk, and taking multivitamins are all ways to up your vitamin D intake. However, vitamin D has to be converted to its active form in the liver and kidneys. Different health problems can affect this process. Medical issues such as Crohn’s disease and celiac disease may contribute to a lower amount of vitamin D as these conditions prevent the absorption of vitamin D from food (Sizar, 2020).
What is liquid vitamin D used for?
Signs and symptoms of vitamin D deficiency
The definition of vitamin D deficiency varies depending on who you ask. There is some argument among experts regarding what levels indicate deficiency. The NIH’s Office of Dietary Supplements and the Institute of Medicine (IOM) define vitamin D deficiency as serum levels of less than 30 nmol/L of 25-hydroxyvitamin D (a form of vitamin D in your blood). However, the Endocrine Society has a different measure of vitamin D deficiency; they define vitamin D deficiency as 25-hydroxyvitamin D blood levels below 50 nmol/L (NIH, 2021).
A vitamin D deficiency can be hard to catch because the signs and symptoms often depend on the severity and duration of the low vitamin D levels. Mild to moderate deficiency may have no symptoms at all. Noticing the signs can help you start a discussion with your healthcare provider about your concerns.
The primary role of vitamin D is to support bone health. It helps you absorb calcium and phosphate, two minerals necessary for healthy bones. Vitamin D is vital to maintaining the balance of bone growth and resorption. Without enough vitamin D, your calcium levels drop, thereby triggering bone breakdown—this leads to thin and brittle bones, also known as osteomalacia. Osteomalacia can also cause bone pain and muscle pain. Low vitamin D levels may also contribute to osteoporosis in older adults (Dawson-Hughes, 2020).
In addition to osteomalacia, vitamin D deficiency in children can also lead to a medical condition called rickets. Rickets happens when growing bones don’t get enough calcium and phosphate. Without these essential minerals, the bone does not harden or mineralize, leading to bone softening and weakening. Symptoms of rickets include delayed growth, bow legs, weakness, and back pain (Misra, 2020).
Given its importance to bone health, it is not surprising that bone pain can be a symptom in people who are vitamin D deficient. Both osteomalacia and rickets can cause bone pain.
Other possible symptoms
Other signs and symptoms may be effects of vitamin D deficiency, but there is limited data to support these associations. Non-specific findings that could be related to your vitamin D levels include (Bouillon, 2021):
- Getting sick often or having a weakened immune system
- Muscle weakness
- High blood pressure
- Cardiovascular disease
- Depression and anxiety
- Lung problems
- Multiple sclerosis
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Risk factors for vitamin D deficiency
Anyone, regardless of race, age, country of residence, etc., can have low vitamin D levels. However, certain factors increase the risk of vitamin D deficiency. People at increased risk of deficiency include (Dawson-Hughes, 2020):
- Older adults
- People with limited sun exposure
- Those who live in high latitude areas or places with poor air quality
- People with darker skin pigmentation
- People with obesity
- Those taking certain medications (like phenytoin) that speed up vitamin D breakdown
- People staying long-term in a hospital or nursing home
- Those with medical problems, like inflammatory bowel disease and celiac disease, that prevent vitamin D absorption
Certain other lifestyle and cultural factors that reduce skin sunlight exposure can be involved, too.
Treatment of vitamin D deficiency
If you suspect you have low vitamin D values, talk to your healthcare provider. You may need to get blood tests to check your 25-hydroxy vitamin D blood levels (which you may see abbreviated as 25(OH)D).
Deficiency sometimes requires a short-time regimen of vitamin D supplementation that should be monitored by a medical professional. Most providers replace vitamin D using cholecalciferol (vitamin D3) tablets, although ergocalciferol (vitamin D2) is also an option. Ensure that you’re working with a medical professional, as too much vitamin D can cause vitamin D toxicity (Dawson-Hughes, 2020).
Prevention of vitamin D deficiency
You may be tempted to spend more time in the sun to get more vitamin D. While sunlight is our primary source of the vitamin, sitting in the sun for too long can lead to skin cancer. You should always wear sunscreen to protect yourself from the dangers of UV light. The safest and easiest method of prevention may be in the kitchen.
Stock up on good food sources of vitamin D, such as fatty fish (like sockeye salmon, mackerel, cod liver oil, and herring), egg yolks, beef liver, dairy products, and fortified foods (orange juice and certain breakfast cereals).
You don’t necessarily need to add a vitamin D supplement to your regimen unless your healthcare provider has tested your levels and recommends supplementing. The Office of Dietary Supplements recommends most adults need 600 international units (IU) of vitamin D per day; people over 71 may require up to 800 IU per day (NIH, 2021).
- Bouillon, R. (2021). Vitamin D and extraskeletal health. In UptoDate. Rosen, C.J. and Mulder, J.E. (Eds.). Retrieved from https://www.uptodate.com/contents/vitamin-d-and-extraskeletal-health
- Dawson-Hughes, B. (2020) Vitamin D deficiency in adults: definition, clinical manifestations, and treatment. In UptoDate. Drezner, M.K, Rosen, C.J, and Mulder, J.E. (Eds.). Retrieved from https://www.uptodate.com/contents/vitamin-d-deficiency-in-adults-definition-clinical-manifestations-and-treatment
- Forrest, K. Y., & Stuhldreher, W. L. (2011). Prevalence and correlates of vitamin D deficiency in US adults. Nutrition Research, 31(1), 48–54. doi: 10.1016/j.nutres.2010.12.001. Retrieved from https://pubmed.ncbi.nlm.nih.gov/21310306/
- Mahamid, M., Abu-Elhija, O., Samamra, M., Mahamid, A., & Nseir, W. (2014). Association between vitamin D levels and alopecia areata. The Israel Medical Association Journal, 16(6), 367–370. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/25058999
- Martineau, A. R., Jolliffe, D. A., Hooper, R. L., Greenberg, L., Aloia, J. F., Bergman, P., et al. (2017). Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ (Clinical research ed.), 356, i6583. doi: 10.1136/bmj.i6583. Retrieved from https://pubmed.ncbi.nlm.nih.gov/28202713/
- Misra, M. (2020) Vitamin D insufficiency and deficiency in children and adolescents. In UptoDate. Motil, K.J., Drezner, M.K, and Hoppin, A. G. (Eds.). Retrieved from https://www.uptodate.com/contents/vitamin-d-insufficiency-and-deficiency-in-children-and-adolescents
- National Institutes of Health (NIH), Office of Dietary Supplements – Vitamin D. (2021). Retrieved Apr 28, 2021 from https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
- Sizar O, Khare S, Goyal A, et al. Vitamin D Deficiency. (2020). In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Retrieved Apr 29, 2021 from: https://www.ncbi.nlm.nih.gov/books/NBK532266/