By: Chelsea Rae Bourgeois, MS, RDN, LD

Vitamin D, often referred to as the sunshine vitamin, is both a nutrient we eat and a hormone our bodies make. It’s well-known that this fat-soluble vitamin supports bone health by regulating the absorption of calcium, but did you know it plays a role in many other bodily functions as well?¹ 

Research shows that Vitamin D supports normal immune health, muscle function, and brain cell activity. Some studies have even shown that Vitamin D can reduce cancer cell growth, help control infections, and reduce inflammation. Many of the body’s organs and tissues have receptors for the vitamin, encouraging continued research regarding its role in the human body.¹

Vitamin D Sources

Vitamin D can be obtained from foods and supplements and through the chemical reaction that occurs when our skin is exposed to sunlight. Very few foods are naturally rich in Vitamin D, but fatty fish such as salmon, tuna, and mackerel are among the best sources.¹ 

Beef liver, egg yolks, mushrooms, and cheese also provide small amounts. Furthermore, many fortified foods are available to help consumers meet their needs. For example, orange juice, cereals, dairy products, and plant-based milk are commonly fortified with Vitamin D.¹

When exposed to the sun’s UVB light, our bodies also make Vitamin D. The amount of Vitamin D that your skin makes may vary based on the season, the time of day, where you live, and the melanin content of your skin.¹ 

Those living in certain areas north of the equator will find the UVB light weaker, affecting the amount of Vitamin D produced. And those who spend much of their time indoors may also see a decreased production of Vitamin D. 

Vitamin D Deficiency

Signs of Vitamin D deficiency include fatigue, bone pain, muscle weakness, and mood changes. When our bodies lack adequate Vitamin D, we risk losing bone density, contributing to osteoporosis and fractures.² 

Low Vitamin D levels have also been associated with cardiovascular disease, cancer, and cognitive impairment in older adults. Researchers are studying the vitamin’s possible connection to other health concerns such as hypertension, diabetes, and other autoimmune diseases.

Treating Vitamin D Deficiency

Whether preventing or treating Vitamin D deficiency, the goal is to reach and maintain an adequate level of Vitamin D within the body. Eating foods rich in the vitamin and catching a bit more sunlight may be beneficial, but if your levels are trending low, your provider will likely recommend supplementation.

Vitamin D comes in two forms: D2 and D3. D2, also known as ergocalciferol, comes from plants, while D3, known as cholecalciferol, comes from animals.² D3 tends to be more easily absorbed in the body and does not require a prescription. However, it is important to discuss options with your healthcare provider to find the right treatment plan for your needs.

References

1. National Institutes of Health. Vitamin D.
2. Parva NR, Tadepalli S, Singh P, et al. Prevalence of Vitamin D Deficiency and Associated Risk Factors in the US Population (2011-2012). Cureus. 2018;10(6):e2741. Published 2018 Jun 5. doi:10.7759/cureus.2741