Do you need a Vitamin D supplement?

Do you need a Vitamin D supplement?

How do you know if you need a Vitamin D Supplement?

Winter seems to be a difficult time for many people living in northern latitudes. In Maryland, where I have lived for the past twenty years, we get less than ten hours of sunlight a day in December and January.  

Sunshine brightens our moods. After a difficult, sad day, we like to sing with Annie, “The Sun Will Come Out Tomorrow. Bet Your Bottom Dollar that Tomorrow, There’ll be Sun.” 

However, in December, January, and even February, my husband drives to work before the sun rises. He works in a large building without access to natural light. And then he drives home around sunset. As the winter months drag on, his mood becomes heavier, his thoughts darker, and his exhaustion deeper as he always seems to be fighting a respiratory illness during these months. 

Luckily for us, he was required to have a yearly physical. A few years ago, in April, after a completely difficult and dark winter which he was still struggling to shake off, he was notified his Vitamin D level was extremely low. 


Vitamin D Health Facts 

Our natural source of Vitamin D comes from the sun synthesizing cholesterol found in layers of our skin. Some foods like fatty fish, beef liver, and fortified milk, juice, and cereals can also increase our Vitamin D intake. 

Vitamin D blood levels between 20 and 50 ng/mL are considered adequate for healthy people. To maintain an adequate Vitamin D blood level, the National Institutes of Health (NIH) recommend children, teens, and adults get 600 International Units (IU) of Vitamin D each day while adults over age 70 get 800 IU. 


Possible Side Effects of Long-Term Vitamin D Deficiency  

The most serious side effect of long-term Vitamin D deficiency is frail, brittle bones. Vitamin D is required for the body to sufficiently absorb calcium. Since our bones are mostly composed of calcium, if we don’t get enough Vitamin D, then we won’t have strong bones. 

Vitamin D is important to our overall health several of other ways. Low Vitamin D levels are a contributing factor in the following health issues: 

  • Chronic Fatigue – A primary care facility conducted a study on 171 patients complaining of low energy levels that negatively impacted their daily lives. Blood tests revealed a high number of these patients had low Vitamin D levels. After five weeks of Vitamin D supplementation, Vitamin D levels were normalized and patients’ self-reported fatigue scores were greatly reduced. 
  • Frequent Respiratory Tract Infections – The NIH confirms Vitamin D is necessary to bolster the immune system in fighting off bacterial and viral infections. Recently, Northwestern University researchers suggest that Vitamin D deficiency is linked to major complications and increased mortality rates for individuals battling COVID-19. Clinical trials are ongoing to determine if Vitamin D supplementation could help prevent or decrease the severity of COVID-19. 
  • Bone and Low Back Pain – In observational studies of thousands of women, low levels of Vitamin D were associated with severe back pain that limited daily activities. Other studies relate bone pain in the joints, legs, and ribs with a Vitamin D deficiency. 
  • Muscle Cramps and Spasm – In advising health professionals, NIH ties inadequate calcium absorption, due to low levels of Vitamin D, with involuntary muscle contractions resulting in cramps and spasm. (My husband suffered from painful cramps in his calves at night.)
  • Declined Cognitive Functioning - Studies indicate the valuable role Vitamin D plays in neurodevelopment, function, and protection. One analysis conducted in 2017 believes there is an increased risk of dementia in adults over age 65 when Vitamin D levels are below 10 ng/mL. 
  • Depression – Observational studies show a link between Vitamin D deficiency and depression. However, clinical trials do not show this link. One abstract by Penckofer, et al. hypothesizes depression is a secondary condition caused by chronic ill health that is related to Vitamin D deficiency. 

Who is at Risk for being Vitamin D Deficient?  

  • People who cannot efficiently obtain Vitamin D naturally from sunshine. These people include individuals who cover their skin with clothes or sunscreen, individuals with darker skin, and individuals living at latitudes >34 degrees north or south of the equator. (Maryland is at 39 degrees north of the equator.) 
  • Solely breastfed infants. 
  • Those who do not regularly consume food sources rich in Vitamin D. These sources are fatty fish including salmon, mackerel, and tuna, beef liver, egg yolks, and Vitamin D fortified milk or breakfast cereals. 
  • Obese individuals. Fat tissue binds Vitamin D and prevents its circulation in the body. 
  • Adults age 70 years or older - Older adults’ skin is less effective at generating Vitamin D. Also, their kidneys are less able to convert Vitamin D to its active form. 
  • People with eating disorders like Crohn’s or Celiac disease. These diseases don’t handle fat properly. Vitamin D is a fat-soluble vitamin requiring fat for proper absorption. 

Possible Long-Term Health Benefits of Sufficient Vitamin D 

In the NIH fact sheet for health professionals, the following long-term benefits of adequate Vitamin D levels are given. 

  1. Good Bone Health 
  2. Reduce Cancer Mortality Rates 
  3. Possible Reduction in Type 2 Diabetes 

The doctor recommended my husband began taking a daily 4,000 IU of a Vitamin D3 supplement. Within a month, his mood was lighter and the lingering fatigue and cough evaporated. 

If you are struggling with chronic fatigue, recurrent respiratory illnesses, low back pain, or depression, check with your doctor. You may be suffering from insufficient Vitamin D, too. A supplement might be the answer you so desperately need. 


Article by Jae O. Haroldsen



Penckofer, Sue PhD, RN et al. “Vitamin D and Depression: Where is all the Sunshine.” Issues in Mental Health Nursing. 2010.

Spritzler, Franziska. “8 Signs and Symptoms of Vitamin D Deficiency.” Healthline. 2018.

Vitamin D Deficiency. Diet and Weight Management. WebMD.

Vitamin D Fact Sheet for Consumers. National Institute of Health: Office of Dietary Supplements. 2020.

Roy, Satyajeet et al. “Correction of Low Levels of Vitamin D Improves Fatigue: Effect of Correction of Low Vitamin D in Fatigue Study.” North American Journal of Medical Sciences. 2014.

Anjum, Ibrar et al. “The Role of Vitamin D in Brain Health: A Mini Literature Review.” Cureus. 2018.

“Vitamin D Fact Sheet for Health Professionals.” National Institute of Health: Office of Dietary Supplements. 2020.

Northwestern University. “Vitamin D Levels Appear to Play in COVID-19 Mortality Rates.” Science News. 2020.

Olena, Abby. “Trails Seek to Answer if Vitamin D Could Help in COVID-19.” The Scientist. 2020.


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