Man doing push-ups with bone health supported by vitamin D

3 reasons why your body needs vitamin D

Medically reviewed by Rosanna Sutherby, PharmD on August 11, 2020. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Why do we need vitamin D? The “sunshine vitamin” is well-known as a nutrient that helps build strong muscles and healthy bones by increasing the body’s ability to absorb calcium and phosphorus. But in recent years, it’s been shown to play a role in other aspects of health, as well—and here we’ll highlight some of those findings to help explain why the body needs vitamin D, so read on.

(Note: you can easily check your vitamin D levels with the at-home Vitamin D Test.)

Why do we need vitamin D?

From bone development to supporting immune system function, here are some of the top reasons your body needs vitamin D.

1. Vitamin D helps support overall health

Adequate vitamin D levels may help lower the risk of certain health conditions and reduce the severity of others—making it an important nutrient for supporting your overall health. Here’s a look at some of these health conditions.


Over 53 million adults in the United States either have—or are at risk of developing—osteoporosis. Osteoporosis is a disease that is characterized by the deterioration of bone tissue or low bone mass, which increases the risk of bone fractures. An insufficient vitamin D level reduces calcium absorption and thus contributes to osteoporosis.


In some people, applying vitamin D to the skin (or a topical mixture that contains a vitamin D compound called calcipotriene) helps treat plaque-type psoriasis.


Rickets is a rare condition that may develop in children with a vitamin D deficiency and causes the bones to soften and distort (often leading to bow legs, delayed growth, and muscle weakness). To help avoid this condition from developing, if your are pregnant or breastfeeding be sure to ask your healthcare provider about vitamin D supplementation for your newborn.

Additional health conditions

Some research also suggests that getting enough vitamin D may help prevent type 1 and type 2 diabetes. Other conditions that vitamin D may help prevent include multiple sclerosis, glucose intolerance, and hypertension. Note, however, that these research findings are not conclusive and more studies are needed to determine the extent to which vitamin D affects the risk for these conditions.

2. Vitamin D supports the growth and development of bones, teeth, and muscles

One key reason why we need vitamin D has to do with our bones, teeth, and muscles. Vitamin D helps calcium and phosphorus build bones, teeth, and muscles—and keep them strong and healthy. Vitamin D, whether it’s taken through vitamin D supplementation or through sunshine exposure, is converted to an active form of the vitamin that helps promote the absorption of calcium from one’s diet (and avoid poor bone health, such as weak bones and loss of bone density).

3. Vitamin D supports cell and immune function

Vitamin D also helps modulate cell growth, supports neuromuscular and immune function, and may reduce inflammation. (You can check both vitamin D and inflammation levels with the Everlywell at-home Vitamin D & Inflammation Test.)

How to get enough vitamin D

If you were wondering "How much vitamin D do I need?" then you might also be interested in learning how to get more vitamin D. In general, you can get enough vitamin D through certain vitamin D-rich foods in your diet (including fortified foods), exposing skin to sunlight, and vitamin D supplementation.

Vitamin D can be found in oily fish, also called fatty fish, like salmon, tuna (including canned tuna), and mackerel. Small amounts can also be found in beef liver, egg yolks, and cheese. In addition, various fortified foods like milk and cereal—as well as some brands of yogurt and orange juice—are often made with vitamin D.

When it comes to sun exposure and UV rays (ultraviolet rays is the kind of sunlight that helps generate vitamin D in the skin), getting 5-30 minutes of exposure two days a week is usually sufficient for the body to produce adequate vitamin D levels, according to some researchers. However, several factors can affect the amount of vitamin D your skin makes through exposure to sunlight—including the season, time of day, where you live, and the melanin content of your skin.

If you find that you aren’t getting sufficient vitamin D from food sources or exposure to sunlight, taking vitamin D supplements may be an effective option—but it’s a good idea to consult with your healthcare provider first before taking a vitamin D supplement.

How to check for vitamin D deficiency

If you’re concerned you might have low vitamin D levels, consider taking our vitamin D home test. You can use this test to easily check if your levels are too low (or too high)—from the convenience of home—with fast, secure online results.

What should vitamin D levels be?

8 possible causes of low vitamin D levels

3 easy ways to get vitamin D


1. Vitamin D. NIH, Office of Dietary Supplements. URL. Accessed August 11, 2020.

2. Barrea L, Savanelli MC, Di Somma C, et al. Vitamin D and its role in psoriasis: An overview of the dermatologist and nutritionist. Rev Endocr Metab Disord. 2017;18(2):195-205. doi:10.1007/s11154-017-9411-6

3. Vitamin D Deficiency. Cleveland Clinic. URL. Accessed August 11, 2020.

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