Vitamin D: An Important Key to Optimal Health

vitamin D foods
Healthy foods containing vitamin D.

Are you tired of feeling sick or depressed?  Is your immune system compromised?  Do you feel older than you are?  Consider nutrition to help you get back on the right path.  A Vitamin D deficiency may be contributing to poor health.

Vitamin D: What is it?

Vitamin D or the “Sunshine Vitamin” is an essential fat-soluble vitamin that is important for absorption/healthy function in the body.

Why We Need It

Vitamin D can have an effect on almost anything in your body. Studies show Vitamin D health benefits including reducing the risk of chronic diseases, common cancers, and cardiovascular diseases (Holick, 2009.)

Some other health benefits of Vitamin D include that it may:

  • Lessen pain related to muscle/bone issues
  • Regulate Hormones
  • Slow the aging process
  • Increase sexual health
  • Aid in fertility
  • Lower the risk for Type I &Type II Diabetes
  • Increases lung capacity in asthmatics
  • Lessens the risk for Dementia and Alzheimer’s
  • Improves mood and lessens depressive symptoms
  • Provides energy for the body
  • Increase mood levels
  • Reduces the risk of migraines/headaches
  • Prevent cancers
  • Prevents viral and immune systems
  • Lessens inflammation
  • Stimulates Osteocalcin, an important bone-building protein
  • Helps regulate blood pressure
  • Reduce the risk of heart disease

How Much We Need/How We Get It

Currently, the adult recommended dietary allowance for Vitamin D is 600-800 International Units (IUs) or .015-.025 milligrams per day. However, according to the Institute of Functional Medicine, a person lacking Vitamin D should have approximately 5,000 IU daily. And the National Academy of Medicine agrees that taking that much vitamin D is completely safe as long as one is not surpassing their optimal levels of the vitamin. While people may get Vitamin D from the sun as well as from food consumption, it is hard to reach the recommended dosage that way.  For comparison, an ounce of Swiss cheese has 6 IUs. 

At D-Signed Nutrition, we monitor blood levels of vitamin D.  Vitamin D is measured as 25 hydroxyvitamin D or 25 (OH) D.  The level for optimal health is 60-80 nanograms per milliliter.  The range for vitamin D on a standard lab is 30-100.  As you can see, this is a large range. 

Having blood work tested by your health care provider can help you check your vitamin D levels to confirm or rule out vitamin D deficiency.

In our office, we always treat to the lab value and we try to get close to optimal with supplements.  According to researchers at Harvard Medical School, everyone should be taking vitamin D if he/she is deficient.  It is important to recheck vitamin D levels at least once a year to monitor and adjust supplementation doses.

Vitamin-D and Genetics

The most clinically significant genes for monitoring Vitamin D Status are DHCR7, CYP2R1, and GC. Those with mutations in these genes may have trouble absorbing, due to an error in the synthesis stage, activation stage, or transport stage of Vitamin D absorption. People with a mutation in any of these genes may be vitamin D deficient due to these genetic errors.  At D-Signed Nutrition, we encourage genetic testing and offer a cost-effective health interpretation that includes vitamin D gene variants.

Vitamin-D Relevance to Covid-19 and other infections

Your immune system has a major job. It is fighting off antibodies that are trying to harm you every single day. It has a huge role in your body, keeping you healthy and fighting off foreign bodies such as bacteria, and viruses. If one has a weak immune system, it’ll be harder to fight off any illness or virus, including Covid-19. Since Vitamin D is crucial to obtaining a healthy immune system, people with higher Vitamin D levels may be less at risk for fighting off viruses. 

According to the Journal of Clinical Endocrinology & Metabolism, a population-based cohort study in Spain was performed to measure the levels of Vitamin D in Covid 19 patients and also in Controls. The study concluded with findings that Vitamin D-deficient Covid-19 patients had a greater prevalence of resulting co morbidities than those without significant deficiencies (levels ≥20 ng/mL.). (González-Molero I, Morcillo S, Valdés S 2001).”

However, in terms of the severity of the virus once caught,  there was no correlation between  the severity of the virus and a person’s Vitamin D levels. . Future studies with a larger sample size may be needed to determine the impact of vitamin D deficiency on the severity of COVID-19..(Hernández, Nan, Ayala, Unzueta, Hernández-Hernández, López-Hoyos, Muñoz-Cacho, Olmos, Gutiérrez-CuadraRuiz-Cubillán, Crespo, Martínez-Taboada 2021)

That said, one should not overdose on vitamin D in order to prevent Covid-19 as high doses of vitamin D can cause other severe symptoms, such as kidney issues, stomach pain, and possible death.(Shmerling, 2021). Having the optimal amount will be more effective than too much. Check with your health care provider to confirm the optimal dose for you.

The researchers at Harvard medical school are urging people to reach optimal Vitamin D levels, regardless of whether or not they believe in the correlation between Vitamin D and Covid-19 prevention. While there are several efficacious studies showing the benefits of Vitamin D, and Covid-19, it is a new concept that is still undergoing study. However, there is no denying the benefits and importance of Vitamin D for a person’s overall health.

Let our team at D-Signed Nutrition help you maximize your nutritional health, including your vitamin D status.  Call our office today at 239-676-5249.  We can help you feel better!


González-Molero I, Morcillo S, Valdés S, et al.  Vitamin D deficiency in Spain: a population-based cohort study. Eur J Clin Nutr. 2011;65(3):321-328. 2021

Holick, M. F., MD. (2009). Vitamin d status: Measurement, interpretation, and clinical application. Annals of Epidemiology, 19(2), 73-78. doi:10.1016/j.annepidem.2007.12.001

José L Hernández, Daniel Nan, Marta Fernandez-Ayala, Mayte García-Unzueta, Miguel A Hernández-Hernández, Marcos López-Hoyos, Pedro Muñoz-Cacho, José M Olmos, Manuel Gutiérrez-Cuadra, Juan J Ruiz-Cubillán, Javier Crespo, Víctor M Martínez-Taboada, Vitamin D Status in Hospitalized Patients with SARS-CoV-2 Infection, The Journal of Clinical Endocrinology & Metabolism, Volume 106, Issue 3, March 2021, Pages e1343–e1353,

Shmerling, R. H., MD. (2021, April 06). Do vitamin D, zinc, and other supplements help prevent COVID-19 or hasten healing? Retrieved April 12, 2021, from

T. (Ed.). (2021, February 22). The functional medicine approach to COVID-19: Virus-Specific NUTRACEUTICAL and BOTANICAL AGENTS. Retrieved April 26, 2021, from