This blog post was written by Katie Keating, RN, MS, patient advocate.

Vitamin D, also known as the “sunshine” vitamin, is vital to your physical and mental health. Although it has the word vitamin in its name, vitamin D is technically a hormone. It is an essential fat-soluble nutrient. Unlike many other essential nutrients, your body can make vitamin D, synthesizing it when your skin is exposed to the sun. You can also get it through foods and supplements.¹

Risk factors for vitamin D deficiency

Sunlight exposure is the primary source of vitamin D for most people. The amount of sun exposure you need will depend on your climate, the time of day, and the time of year. People with lighter skin tend to absorb vitamin D more quickly. People who have darker skin have greater amounts of melanin, a natural pigment that gives skin it’s color. Melanin reduces vitamin D production in the skin. An individual may need anywhere from 15 minutes to 3 hours of sun exposure per day to get enough vitamin D from sun exposure alone.

Diet — Few foods are naturally rich in vitamin D. However, great natural sources of vitamin D include salmon, mackerel, other fatty fish, fish liver oils, animal fats, and vitamin D-fortified food products such as orange juice and some cereals.

Higher latitudes — Studies published in The Journal of Nutrition and The Journal of the American Osteopathic Association both found that people living in northern latitudes (such as the northern half of the United States) may be more likely to have lower vitamin D levels.

Obesity — A link exists between vitamin D deficiency and people with a body mass index (BMI) of 30 or higher. People who are obese may need to absorb more vitamin D than people of average weight in order to reach recommended nutrient levels.

Age —As you get older, your skin becomes less efficient at synthesizing vitamin D. Older adults also tend to limit time in the sun and may eat diets with insufficient amounts of vitamin D.²

Vitamin D deficiency

Vitamin D deficiency occurs when the body doesn’t absorb the recommended levels. Insufficient Vitamin D levels can also lead to a number of health problems, including respiratory issues, depression, bone softening (osteomalacia), low bone density (osteopenia), osteoarthritis, heart disease, cancer, and many more.

Vitamin D and respiratory illnesses

Vitamin D plays a role in the immune system and our body's ability to fight off infection; there are vitamin D receptors on immune cells and vitamin D deficiency increases our susceptibility to infection. Lower vitamin D levels lead to inflammation.

Vitamin D and depression

Studies have shown a link between vitamin D deficiency and depression. Researchers behind a 2013 meta-analysis noticed that study participants with depression also had low vitamin D levels. The researchers believe that because vitamin D is important to healthy brain function, insufficient nutrient levels may play a role in depression and other mental illnesses.^3,4

Vitamin D deficiency and osteoporosis

One of vitamin D’s primary roles is to maintain skeletal health. Low levels of vitamin D lead to low bone calcium stores, increasing the risk of fractures. Vitamin D also helps control calcium and phosphate levels in the body. A vitamin D deficiency may put people at risk for osteoporosis, which happens when new bone doesn’t generate at the same pace as the loss of old bone.⁵

Diagnosis of vitamin D deficiency

To diagnose vitamin D deficiency, your doctor will order a test to measure the amount of vitamin D in your blood. Vitamin D is not usually measured in a routine blood test, it must be requested as Vitamin D 25 hydroxy 25(OH)D.⁶

Cholecalciferol is the vitamin D that your own body has made or that you absorbed from an animal source (such as fatty fish or liver) or a cholecalciferol supplement. Ergocalciferol is the vitamin D that you have absorbed from foods fortified with plant Vitamin D or from an ergocalciferol supplement. The important value is the total of Cholecalciferol and Ergocalciferol in your blood.

Causes of Deficiency:

• Lack of skin exposure to sunlight
• Lack of enough vitamin D in diet
• Liver and kidney disease
• Poor food absorption
• Use of certain medicines, including phenytoin, rifampin and phenobarbital
• Advanced age, weight loss surgery, or conditions in which fat is not absorbed well
• Levels of vitamin D are also correlated with the number of “friendly” bacteria in a person’s gut. Bacterial diversity or friendly, microbiome diversity in the gut is associated with better health.⁷

Treating vitamin D deficiency

You can treat vitamin D deficiency and its symptoms by increasing your intake of this vital nutrient via sun exposure, eating foods that are fortified with vitamin D, and or supplements. Supplements come in pill, liquid, and patch forms.

I did not take Vitamin D seriously when I first was diagnosed with NTM/bronchiectasis. I now regret not paying closer attention to it and not having it checked regularly. Again, you must request this lab test from your primary care doctor. Many patients become overwhelmed with tracking the results of visiting so many different specialists and often focus on the acute issues at hand over preventative strategies. Patients often do not always absorb, retain, apply new knowledge when they are not feeling well.

The coronavirus pandemic bought into our awareness how very important vitamin D is for our immune system to function optimally. My recent level was low at 29; 40–60 is recommended. I took liquid vitamin D throughout the pandemic and I am now up to a 46. I feel stronger and mentally relieved that I have more tools in my body’s arsenal to fight any virus or bacteria which may come my way. You deserve to feel stronger and better too! Speak with your doctor about regular vitamin D assessments and your best treatment options. Wishing you the very best!

The COPD Foundation advises that you consult with your doctor before making any changes to your medication or therapies.

1. https://www.verywellhealth.com/vitamin-d-foods-immune-health-5094903
2. https://www.healthline.com/health/depression-and-vitamin-d#risk-factors
3. https://www.healthline.com/health/depression-and-vitamin-d#connection
4. https://www.healthline.com/health/depression-and-vitamin-d
5. https://www.everydayhealth.com/news/illnesses-linked-vitamin-d-deficiency/
6. https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/8822
7. https://www.medicalnewstoday.com/articles/gut-bacteria-and-vitamin-d-what-is-the-link#Stores-of-inactive-vitamin-D

Other References:

https://medlineplus.gov/ency/article/003569.htm
https://www.everydayhealth.com/vitamin-d/what-recommended-daily-intake-vitamin-d/
https://www.everydayhealth.com/news/illnesses-linked-vitamin-d-deficiency/
https://www.resmedjournal.com/article/S0954-6111(19)30018-6/fulltext