Vitamin D: More Than Just a Nutrient, A Key to Good Health

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Vitamin D, called “the Sunshine Vitamin,” is a unique fat-soluble vitamin as it is considered both a nutrient and a pro-hormone (a compound the body can convert to an active hormone). Besides being absorbed from our diet, it can be produced in the skin. It then is activated in the liver and kidneys. The active hormone communicates with a variety of tissues in the body. Vitamin D helps us maintain healthy calcium levels and thus is vital for our bone health. In addition, Vitamin D is essential for improving our immunity while decreasing inflammation, cardiovascular disease, and diabetes risk. Deficiencies are associated with autoimmune disease, cancer, depression, and all causes of death. Studies show that Vitamin D supplementation can reduce pain experienced in fibromyalgia. Notably, some studies have shown that optimizing Vitamin D is protective against infection rates, severe disease, and death from COVID-19.

The Difference Between D2 and D3

Vitamin D3 is cholecalciferol, the form of vitamin D found in animal foods and made by our bodies when exposed to ultraviolet light. Vitamin D2 is ergocalciferol found in plant sources (found naturally in mushrooms). Both Vitamin D3 and D2 supplementation can raise our blood levels, but Vitamin D3 is generally sourced from sheep’s wool. It is typically considered the better choice for supplementation since it is absorbed more effectively and is more similar to what we naturally produce in our bodies. Thankfully, vegan vitamin D3 supplements derived from lichen (algae/fungus) are now available.

Vitamin D Deficiency 

Vitamin D deficiency is the most common nutritional deficiency worldwide, and over 40% of American adults are Vitamin D deficient. Leading causes include sun avoidance, sunscreen, increased skin pigmentation, and age over 50. Inadequate dietary and supplemental vitamin D intake, malabsorption syndromes, obesity, and medication use (including anti-seizure medication, glucocorticoids, and certain AIDS medications) have also been implicated in Vitamin D deficiency.

Our skin produces Vitamin D in response to the sun’s ultraviolet rays (specifically UV-B). We need about 5-30 minutes of sun exposure between 10 am and 3 pm twice a week to our arms and legs or back without sunscreen (but sun protection on the face). People with darker skin where high melanin decreases the ability to make vitamin D need a more prolonged exposure. Furthermore, adults over 50 years old, in whom Vitamin D synthesis is not as efficient, should also get more exposure. Physicians frequently see patients with inadequate Vitamin D levels because we often live in cold climates, work indoors, and use sunscreen.

Negative symptoms of vitamin D deficiency tend to improve once Vitamin D is supplemented to adequate levels. Supplements of Vitamin D3 can also increase inadequate blood levels. The RDA for adults ranges from 600-800 IU/d (15-20 mcg/d) depending on age. Adults should routinely get an upper limit of 2000 IU/d (50 mcg/d) in our foods or through supplementation. Too much Vitamin D can be harmful and cause nausea, weakness, constipation, confusion, and other toxicities. So, testing Vitamin D levels, although controversial, is reasonable. The 25 hydroxy D test falling in a 30-45 ng/ml range is considered adequate. Most people recommend supplementation with Vitamin D3, and 10,000 U of D3 supplementation can raise blood levels by approximately 10 points. Vitamin D-fortified foods (like fortified plant-based milk) can also help.

What about full-spectrum lights? 

Phototherapy is a recognized modality used to improve Vitamin D deficiency. It is instrumental in people who have a medical condition that contributes to malabsorption (like cystic fibrosis or short bowel syndrome). Sun lamps, full-spectrum lights, and light-boxes work by imitating sunlight. Sitting by a light that provides 10,000 lux for 30 minutes a day as soon as possible after waking can help decrease symptoms of Seasonal Affective Disorder. However, those with light sensitivity or eye issues may need to avoid this option. Furthermore, light sources using UV-B wavelengths of light (required for the skin for Vitamin D production) are associated with increased skin cancer risk. Thus, tanning booths are not routinely recommended to increase Vitamin D due to the harm they can cause.

In addition, full-spectrum lights may not be sufficient to provide all of one’s Vitamin D needs. Vitamin D was increased by 36% with phototherapy but 74% with supplementation in one study. Moreover, getting Vitamin D from natural sunlight is better than using a sunlamp in most cases. Getting out in nature provides several benefits for improving Vitamin D that full-spectrum lights do not. Just being in nature can improve mood, and when walking in nature, one decreases stress and increases activity, which enhances health.

In conclusion, while full-spectrum lights and phototherapy offer benefits, particularly for conditions like Seasonal Affective Disorder or Vitamin D deficiency due to malabsorption issues, they are not comprehensive solutions. Natural sunlight remains the most effective source of Vitamin D, offering additional health benefits such as mood enhancement and increased physical activity. Moreover, the risk of skin cancer from UV-B light sources underscores the need for caution and alternative methods like dietary supplements. Ultimately, a balanced approach that includes safe sun exposure, nutritional supplements, and, where appropriate, light therapy, is essential for optimal health and wellbeing.

References

Hossein-Nezhad A, Holick MF. Vitamin D for health: a global perspective. Mayo Clin Proc. 2013 Jul;88(7):720-55

Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30.

Gloth FM 3rd, Alam W, Hollis B. Vitamin D vs broad spectrum phototherapy in the treatment of seasonal affective disorder. J Nutr Health Aging. 1999;3(1):5-7. PMID: 10888476.

Chandra P, Wolfenden LL, Ziegler TR, et al. Treatment of vitamin D deficiency with UV light in patients with malabsorption syndromes: a case series. Photodermatol Photoimmunol Photomed. 2007;23(5):179-185. doi:10.1111/j.1600-0781.2007.00302.x

Xue Li, Jos van Geffen, Michiel van Weele, Xiaomeng Zhang, Yazhou He, Xiangrui Meng, Maria Timofeeva, Harry Campbell, Malcolm Dunlop, Lina Zgaga, Evropi Theodoratou. An observational and Mendelian randomisation study on vitamin D and COVID-19 risk in UK Biobank. Scientific Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-97679-5

Kaufman HW, Niles JK, Kroll MH, Bi C, Holick MF. SARS-CoV-2 positivity rates associated with circulating 25-hydroxyvitamin D levels. PLoS One. 2020 Sep 17;15(9):e0239252. doi: 10.1371/journal.pone.0239252. PMID: 32941512; PMCID: PMC7498100.

About the Author:  

Kim Scheuer, MD is board certified in both Family Practice and Lifestyle Medicine, is conversant in Spanish and American Sign Language, and is licensed to see patients in 25 states. She practices telemedicine at Love.Life Telehealth and started DOKS Lifestyle Medicine. 

Dr. Scheuer loves to share what she has learned with all who want to be healthier and happier.