Vitamin D: Benefits and Deficiencies

6 Minute Read

Vitamin D is your sunshine hormone that over a billion people are estimated to be deficient in worldwide and at least 50% of people are at insufficient levels.

What does vitamin D do?

Vitamin D is a fat-soluble vitamin that functions as a hormone in the body, meaning it acts as an important messenger to your cells. It helps regulate calcium absorption to affect levels of calcium and phosphorus, which are important in bone development and metabolism. Rickets is a bone disease that can develop in children whose vitamin D levels are extremely low over an extended time period. However, vitamin D is now known to affect the body in MANY ways highlighting how important it is to maintain proper levels!

Vitamin D is needed for:

Bone health! Vitamin D is needed for calcium absorption in the gut. This process regulates bone mineralization, bone development, and bone remodeling. Low vitamin D in adults will contribute to osteoporosis. Very low vitamin D in children causes rickets, which causes the softening of bones (bowed legs). Rickets is not seen often in the United States anymore.

Immune function. Studies now show there is an increase in susceptibility for infections and autoimmune diseases in people that are vitamin D deficient. Neurological function. Vitamin D enters into the brain and affects your neural cells. Studies show it impacts brain health and is associated with depression. Studies also show that maintaining proper vitamin D levels can have a protective effect and decrease the risk for multiple sclerosis.

Insulin response. Studies show that vitamin D deficiency can play a role in the development of insulin resistance.

Heart health. Several studies have shown that low vitamin D levels cause an increased risk in cardiovascular disease, stroke, and hypertension.

What happens when your vitamin D is too low?

Vitamin D deficiency can cause obesity, diabetes, cardiovascular disease, autoimmune diseases, such as fibromyalgia and chronic fatigue syndrome, osteoporosis, and neurological diseases. Vitamin D also plays a role in a healthy immune response, mood, depression and low levels may contribute to the development of cancer.

How do we obtain vitamin D?

Vitamin D is rare in that we don't obtain the majority of it from our food! We obtain vitamin D three ways: sun exposure, food, and dietary supplements. The majority of Vitamin D is made in the skin when it is exposed to UV rays from the sun. Vitamin D can also be found naturally in very few foods, including fatty fish, egg yolks and beef liver.

Vitamin D produced via sunlight in the form of vitamin D3, which is then converted to an active form in the liver and kidneys. Vitamin D2 is commonly found in supplements, which needs to be converted to D3 and then into the active form. It's thought that D2 takes a long time to convert, so D3 is preferable as a supplement.

People with darker skin often are more at risk for low vitamin D as melanin in the skin absorbs ultraviolet light needed to make vitamin D. So, the amount of vitamin D supplementation will vary based on many factors, including melanin levels.

What is a healthy vitamin D level?

Functional Medicine vs Conventional Medicine Levels

In conventional medicine, the minimum amount of vitamin D that a patient "needs" is 25-30 ng/ml. In reality, that is the amount of serum vitamin D needed for you to stay alive, not to be at in your best health! In functional medicine, we really look at the patient, their overall health, disease status, lifestyle, etc to determine the proper amount of vitamin D needed to live their best life!

The following chart shows disease incidence prevention by vitamin D serum levels gathered through several studies. The baseline of 25 ng/ml was used to compare to disease incidence. The percentage (%) reflect disease prevention at that serum level as compared to the baseline. For example, breast cancer incidence is reduced by 34% when the serum level is 34 ng/ml compared to the baseline of 25 ng/ml.

Vitamin D Percent Reduction of Disease Incidence

Looking at disease incidence prevention, we can see that 25 ng/ml is low!

How much vitamin D should I take daily?

It really depends on the person - health status, skin color, amount of sun exposure, and diet will all play a role in how much vitamin D your body is making on its own. I always recommend my patients to get tested for vitamin D levels so that we can determine the amount of IU that should be taken in the short-term and for long-term maintenance levels.

If you are interested in testing, visit me at consultation.

References: Anjum, I., Jaffery, S., Fayyaz, M., Samoo, Z., & Anjum, S. (2018, July 10). The Role of Vitamin D in Brain Health: A Mini Literature Review. Retrieved August 17, 2020, from

Aranow, C. (2011, August). Vitamin D and the immune system. Retrieved August 17, 2020, from

Danik, J., & Manson, J. (2012, August). Vitamin d and cardiovascular disease. Retrieved August 17, 2020, from

Disease Incidence Prevention Chart. (2017). Retrieved August 17, 2020, from

Naeem, Z. (2010, January). Vitamin d deficiency- an ignored epidemic. Retrieved August 17, 2020, from

Office of Dietary Supplements - Vitamin D. (n.d.). Retrieved August 17, 2020, from Sizar, O. (2020, July 04). Vitamin D Deficiency. Retrieved August 17, 2020, from

Szymczak-Pajor, I., & Śliwińska, A. (2019, April 6). Analysis of Association between Vitamin D Deficiency and Insulin Resistance. Retrieved August 17, 2020, from

Yin, K., & Agrawal, D. (2014, May 29). Vitamin D and inflammatory diseases. Retrieved August 17, 2020, from

Request a Consultation