Vitamin D is a fat-soluble vitamin that is not commonly found in foods. Good sources of vitamin D include fortified cereal, fortified milk, and fish with high fat content such as salmon. This nutrient is also produced endogenously through skin exposure to the ultraviolet rays from the sun. Vitamin D made available to the body through sun exposure, food, and supplements is organically inactive and must go through a chemical process that introduces a hydroxyl group (-OH) into an organic compound (hydroxylation). This chemical process converts vitamin D to calcidiol and calcitriol, which the body can absorb.¹

Vitamin D in the Body

Vitamin D is necessary in the body to promote calcium absorption, bone growth, and bone remodeling. Low levels of vitamin D have been associated with many chronic illnesses, inflammatory conditions, and increased risk for mortality. Vitamin D deficiency and insufficiency have been associated with common cancers, autoimmune ailments, infectious conditions, and cardiovascular disease.² Deficiency causes rickets in children and osteomalacia in adults. In conjunction with calcium, vitamin D helps to prevent osteoporosis in older adults. Vitamin D has receptors in almost every cell of the body.³ Aside from promoting bone health, vitamin D is involved in other body processes such as cell growth modulation, immune function, inflammation reduction, and neuromuscular activity. Over 200 genes, including those involved in cell proliferation, cell differentiation, angiogenesis, and apoptosis, need vitamin D.³ Vitamin D is needed to regulate cells in various tissues, including epidermal keratinocytes. This is done by modifying growth factors and cytokines. Vitamin D can affect wound healing by increasing the production of epidermal and platelet growth factors.⁴

Dietary Reference Intakes

The Food and Nutrition Board of the National Academy of Medicine defined the Dietary Reference Intakes (DRI) for vitamin D based on the daily intake required to promote bone health and adequate calcium metabolism in healthy adults. The DRI of vitamin D is 400 international units (IU) for children up to 12 months of age, 600 IU for ages 1 to 70, and 800 IU for people over 70.³

Vitamin D and Wound Healing

Insufficient sun exposure and chronic illness continues to vitamin D deficiency in people of all ages. Vitamin D deficiency, defined as less than 20 ng/mL, and insufficiency with levels between 20-30 ng/mL affect approximately 1 billion individuals globally.⁵ Vitamin D has recently been shown to display beneficial effects in various vascular diseases by promoting angiogenesis and inhibiting inflammatory responses. A study examining the role of vitamin D in cutaneous wound healing in streptozotocin-induced diabetic mice concluded that supplementation with vitamin D can significantly accelerate wound healing rate.⁶ Razzaghi and colleagues examined the effect of vitamin D supplementation on wound healing and metabolic status in individuals with diabetic foot ulcers.⁷

Their study concluded that vitamin D supplementation had a positive effect on stabilizing blood glucose and cholesterol levels. The study also reported that vitamin D could have a secondary effect on wound healing as a result of the improved glycemic control status seen in the study subjects.⁷ After assessing the relationship between vitamin D and pressure injuries in community-dwelling older adults, Kalava and associates concluded that vitamin D deficiency was not an independent risk factor for pressure injury development.⁸

Implications for Practice

Although the relationship between vitamin D supplementation and wound healing has not been clearly established, we know that this nutrient is essential to maintain bone health. Vitamin D deficiency and insufficiency are very common and can have a negative impact on health and well-being. Reversing vitamin D deficiency is simple and inexpensive and has been linked to many health benefits.

References

1. Office of Dietary Supplements, National Institutes of Health. Vitamin D: Fact Sheet for Health Professionals. 2017. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/. Accessed September 21, 2018.

2. Regulski M. Addressing vitamin D in the wound clinic. Today's Wound Clinic. 2016;10(11). https://www.todayswoundclinic.com/articles/addressing-vitamin-d-deficie…. Accessed September 22, 2018.

3. Institute of Medicine Food and Nutrition Board. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press; 2010.

4. Guo S, DiPietro LA. Factors affecting wound healing. J Dent Res. 2010;89(3):219–29. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2903966/. Accessed September 21, 2018.

5. Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357(3):266–81. https://www.nejm.org/doi/full/10.1056/NEJMra070553. Accessed September 21, 2018.

6. Yuan Y, Das SK, Li M. Vitamin D ameliorates impaired wound healing in streptozotocin-induced diabetic mice by suppressing NF-κB-mediated inflammatory genes. Biosci Rep. 2018;38(2):BSR20171294. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5835716/. Accessed September 22, 2018.

7. Razzaghi R, Pourbagheri H, Momen-Heravi M, et al. The effects of vitamin D supplementation on wound healing and metabolic status in patients with diabetic foot ulcer: a randomized, double-blind, placebo-controlled trial. J Diabetes Complications. 2017;31(4):766–72.

8. Kalava UR, Cha SS, Takahashi PY. Association between vitamin D and pressure ulcers in older ambulatory adults: results of a matched case–control study. Clin Interv Aging. 2011;6:213–9. https://www.ncbi.nlm.nih.gov/pubmed/21966215. Accessed 9/21/18.

About the Author

Dr. Nancy Munoz is the Assistant Chief for Nutrition and Food Service for the Southern Nevada VA Healthcare System. Teaching healthcare practitioners the role of nutrition as a modifiable risk in the development of pressure ulcers is at the core of her practice. Dr. Munoz has authored and served as expert reviewer for books and manuscripts for numerous professional publications, and the Academy of Nutrition Evidence Analysis Library. She currently serves as the Professional Development Chair for the Dietetics in Healthcare Communities DPG, is a member of the Academy’s Positions Committe and the WoundSource editorial advisory board, and is the current Vice President for the National Pressure Ulcer Advisory Panel.