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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.
Few nutrients have generated as much interest recently as vitamin D, which is said to have numerous benefits like keeping bones strong and preventing cancer. Are you getting enough? If you’re like many Americans, it’s entirely possible that you’re not.
What is vitamin D?
Vitamin D, also known as “the sunshine vitamin,” has a role in several important bodily processes. We can get Vitamin D from food or supplements. It’s also produced when skin is exposed to sunlight, creating a substance processed by the liver and kidneys that plays a number of important roles in our bodies.
Although vitamin D is present in some foods, most of the vitamin D in our bodies comes from the conversion of the substance our body makes naturally to vitamin D by UVA rays (Nair, 2012). At certain times of the year, it can be difficult, if not impossible, to get enough sunlight to produce adequate vitamin D. Experts estimate that 40% of Americans and as many as 1 billion people worldwide may be deficient in vitamin D (Parva, 2018).
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Vitamin D’s role in the body
Vitamin D plays many important roles in the body. One of its most central roles is the regulation of calcium levels, thereby strengthening bones while preventing fractures and osteoporosis (Bischof-Ferrari, 2005). Vitamin D is also involved in supporting the immune system and plays a role in protecting against several cancers, including breast and colon cancer (Aranow, 2011; Song, 2019; Meeker, 2016).
Studies have shown that vitamin D also helps the body regulate blood sugar, both reducing the risk of diabetes and improving blood sugar levels in people who have already been diagnosed with diabetes (Schwalfenberg, 2008) and lowering the risk of cardiovascular diseases like heart disease and stroke (Vacek, 2012).
What are normal vitamin D levels?
A vitamin D level of 20–50 ng/mL is considered to be the normal range. Having a serum vitamin D level below 20 ng/mL is considered to be harmful to your skeletal health (Giustina, 2019). Your healthcare provider can do a simple blood test to determine if you have sufficient vitamin D levels.
Vitamin D deficiency: symptoms, treatment, and prevention
How to get more vitamin D if you’re deficient
To maintain a normal level of vitamin D in the body, the National Institutes of Health recommends a total daily vitamin D intake of 600 IU (15 mcg) for adults up to age 69 and 800 IU (20 mcg) for adults 70 and older, whether through food or through supplements. If your healthcare provider determines that you have a vitamin D deficiency, they may recommend that you add more vitamin D to your diet.
Good sources of vitamin D include fatty fish (such as salmon and tuna), fish oil, fortified milk, eggs, and fortified breakfast cereals. Dietary supplements can also be a good way to increase vitamin D levels in your body. It’s important to remember that supplements are not tightly regulated by the FDA, so it’s important to shop carefully and choose a reputable brand.
Is there such a thing as too much vitamin D?
Absolutely. Because vitamin D regulates the amount of calcium your body absorbs from your diet, high levels of vitamin D can cause excessive uptake of calcium, which itself can cause serious problems. If your healthcare provider recommends adding vitamin D to your diet using a supplement, make sure to choose one that provides the recommended dietary allowance (RDA) of vitamin D.
- Aranow, C. (2011). Vitamin D and the immune system. Journal of Investigative Medicine: The Official Publication of the American Federation for Clinical Research, 59(6), 881–886. Retrieved from https://doi.org/10.2310/JIM.0b013e31821b8755
- Bischoff-Ferrari, H. A., Willett, W. C., Wong, J. B., et al. (2005). Fracture Prevention With Vitamin D Supplementation: A Meta-analysis of Randomized Controlled Trials. JAMA. 293(18), 2257–2264. doi:10.1001/jama.293.18.2257. Retrieved from https://jamanetwork.com/journals/jama/article-abstract/200871
- Giustina, A., Adler, R. A., Binkley, N., et al. (2019). Controversies in Vitamin D: Summary Statement From an International Conference. The Journal of Clinical Endocrinology and Metabolism, 104(2), 234–240. Retrieved from https://doi.org/10.1210/jc.2018-01414
- Meeker, S., Seamons, A., Maggio-Price, L., & Paik, J. (2016). Protective links between vitamin D, inflammatory bowel disease and colon cancer. World Journal of Gastroenterology, 22(3), 933–948. Retrieved from https://doi.org/10.3748/wjg.v22.i3.933
- Nair, R. & Maseeh, A. (2012). Vitamin D: The “sunshine” vitamin. Journal of Pharmacology & Pharmacotherapeutics, 3(2), 118–126. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/
National Institutes of Health (NIH). (n.d.). Office of Dietary Supplements – Vitamin D. Retrieved July 17, 2020 from https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
Parva, N. R., Tadepalli, S., Singh, P., et al. (2018). Prevalence of Vitamin D Deficiency and Associated Risk Factors in the US Population (2011-2012). Cureus, 10(6), e2741. Retrieved from https://doi.org/10.7759/cureus.2741
Schwalfenberg, G. (2008). Vitamin D and diabetes: improvement of glycemic control with vitamin D3 repletion. Canadian Family Physician Medecin de Famille Canadien, 54(6), 864–866. Retrieved from
Song, D., Deng, Y., Liu, K., et al. (2019). Vitamin D intake, blood vitamin D levels, and the risk of breast cancer: a dose-response meta-analysis of observational studies. Aging, 11(24), 12708–12732. Retrieved from https://www.aging-us.com/article/102597/text
Vacek, J. L., Vanga, S. R., Good, M., et al. (2012). Vitamin D Deficiency and Supplementation and Relation to Cardiovascular Health. The American Journal of Cardiology, 109(3), 359-363. Retrieved from https://www.sciencedirect.com/science/article/abs/pii/S000291491102933X