Wellness Workshop: The ‘Sunshine Vitamin’

Article | Bethany Cooper, Health Sciences/Medical Writer & Emergency Nurse

In the summer months, we should be able to make all the vitamin D that we need from sunlight.

However, with the days getting shorter and the nights growing longer, it’s a bit harder to come by. This means we need to be more conscious about getting our vitamin D from other sources.

Vitamin D is one of 24 micronutrients that are critical for human survival. [1] Its main function is to help the body absorb calcium: one of the most important minerals for bone strength. [2] Not only is vitamin D vital for bone health, but it also plays an important role in the immune system, specifically in reducing inf lammation, modulating cell growth, aiding neuromuscular and immune function, and metabolising glucose. [3]

Alongside its main physiological functions throughout the body, vitamin D has been linked to the reduction of cancer cell growth, [4,5] attesting to its multi-system importance for our health and wellbeing.

Where Do We Get Vitamin D?

We can get vitamin D through our diet, including from fatty fish, fish liver oil, egg yolk, and fortified foods, such as milks and cereals. Nicknamed the ‘sunshine vitamin’ due to its synthesis in the skin upon exposure to ultraviolet (UV) rays, vitamin D could be considered an easy fix, given its availability through so many natural sources. However, vitamin D deficiency is one of the most common nutrient deficiencies, affecting an estimated 1 billion people globally. [6,7]

Recommended Levels and Risk Factors

According to the National Institutes of Health (NIH), the recommended average daily intake of vitamin D is 400–800 IU, or 10–20 micrograms. [8] However, the amount of vitamin D a person requires is dependent on numerous factors, including age, ethnicity, geographical location, food availability, latitude, sun exposure and even the season, all of which can affect our vitamin D uptake.

Profound vitamin D deficiency is mostly prevalent among babies and children, women who are pregnant or breastfeeding, older people, people with limited exposure to sunshine, and people with darker skin, [9] with vitamin D deficiency especially common in the developing world. [10] Other populations at risk of deficiency are people in hospital, people with chronic kidney or liver disease, and people with malabsorption syndromes – difficulty with digesting or absorbing nutrients. [11]

Deficiency Complications

Vitamin D deficiency is linked to muscle weakness, loss of bone density and an increased risk of fractures. [12] It is also linked to severe complications including several cancers, cardiovascular disease, type 1 diabetes, multiple sclerosis, rheumatoid arthritis, Parkinson’s disease, high blood pressure and thyroid problems. [13,14,15]

Alongside the physical effects, links to a psychological impact have been noted by researchers. For example, a study by Anglin et al. found that a low concentration of vitamin D is associated with an increased risk of depression. [16]

Symptoms and Diagnosis

Given the vast adverse effects of a deficiency of our sunshine vitamin, it is especially important to improve awareness and recognition of the signs and symptoms.

For children, vitamin D deficiency may be easier to spot, as it can lead to rickets – a condition that affects bone development and causes bone pain, poor growth and weak bones. [17] In adults, the symptoms of vitamin D deficiency can be less obvious, and some people may be asymptomatic. However, when it is chronic, even mild vitamin D deficiency can contribute to an increased risk of osteoporosis, falls and fractures.

Other common symptoms of deficiency may be similar to those of other diagnoses, such as recurrent infections or illnesses, fatigue and muscle weakness, bone and joint pain, common fractures and changes in mood. As it is not recommended to screen asymptomatic individuals for vitamin D deficiency, it is vital for clinicians to take a comprehensive history during the assessment. To confirm the diagnosis, this history can be complemented with a simple blood test to evaluate serum 25-hydroxyvitamin D - the primary circulating form of vitamin D. [18]

Treatment and Global Initiatives

Treatment focuses on preventing and managing deficiency. The amount of supplementary vitamin D required to treat the condition depends on the degree of the deficiency and the underlying risk factors. Treatment usually includes a higher loading dose of vitamin D supplements for around 8 weeks, followed by a maintenance dose once the person’s levels have normalised. [19] These levels should be continually and closely monitored.

The testing of vitamin D levels has increased exponentially in recent years as the deficiency has become more apparent globally. [20] The focus on vitamin D deficiency as a public health concern has resulted in numerous initiatives, including:

• More screening for vitamin D deficiency in asymptomatic high-risk individuals.

• Supplementing vitamin D in certain high-risk groups, such as young children and pregnant or breastfeeding women.

• Systematically fortifying food with vitamin D. [21]

Each public health initiative seeks to improve awareness of and responses to this global health concern, but there is still a long way to go to combat the global effects. Given the importance of vitamin D and the ill effects of deficiency, it is vital that we continue to raise awareness and understanding of our sunshine vitamin amongst the public and professionals.

Bethany Cooper

Health Sciences/Medical Writer & Emergency Nurse

Bethany completed a master’s degree in trauma science in 2019, research from which has recently been accepted for publication in a medical journal. Over the past year Bethany has been working as a health sciences and medical writer. She is passionate about health and encouraging health literacy and patient engagement.

1. Bendik I, Friedel A, Roos FF, et al. Vitamin D: A Critical and Essential Micronutrient for Human Health. Front Physiol 2014; 5:248. https://doi.org/10.3389/fphys.2014.00248

2. Berridge MJ. Calcium Signalling Remodelling and Disease. Biochem. Soc. Trans 2012; 40:297–309. https://doi.org/10.1042/BST20110766

3. Norman AW, Henry HH. Vitamin D. In: Erdman JW, Macdonald IA, Zeisel SH, eds. Present Knowledge in Nutrition, 10th ed. Washington, DC: Wiley-Blackwell, 2012, 199–213

4 Moukayed M, Grant WB. Molecular Link Between Vitamin D and Cancer Prevention. Nutrients 2013; 5(10):3993–4021. https://doi.org/10.3390/nu5103993 5. Fleet JC, DeSmet M, Johnson R, Li Y. Vitamin D and Cancer: A Review of Molecular Mechanisms. Biochem J 2012; 441(1):61–76. https://doi.org/10.1042/BJ20110744 6. Palacios C, Gonzalez L. Is Vitamin D Deficiency a Major Global Public Health Problem? J Steroid Biochem Mol Biol 2013; 144 Pt A:138–45. https://doi.org/10.1016/j.jsbmb.2013.11.003 7. Wahl DA, Cooper C, Ebeling PR, et al. A Global Representation of Vitamin D Status in Healthy Populations. Arch. Osteoporos 2012; 7(1–2):155–72. 8. National Institutes of Health (NIH). Vitamin D: Fact Sheet for Consumers. https://ods.od.nih.gov/factsheets/VitaminD-Consumer (Last accessed October 2022) 9. Patience S. Vitamin D deficiency in at-risk groups. Community Pract 2013; 86(3):38–40. PMID: 23540018 10. Biesalski HK. Hidden Hunger in the Developed World. In: Eggersdorfer M, Kraemer K, Ruel M et al., eds. The Road to Good Nutrition: A Global Perspective. Basel: Karger, 2013, 39–50. 11. Kennel KA, Drake MT, Hurley DL. Vitamin D Deficiency in Adults: When to Test and How to Treat. Mayo Clin Proc 2010; 85(8):752–7. 12. Lips P, van Schoor NM. The Effect of Vitamin D on Bone and Osteoporosis. Best Pract Res Clin Endocrinol Meta 2011; 25(4):585–91. doi: https://doi.org/10.1016/j.beem.2011.05.002 13. Zhang R, Naughton DP. Vitamin D in Health and Disease: Current Perspectives. Nutr J 2010; 9, 65. https://doi.org/10.1186/1475-2891-9-65 14. Nair R, Maseeh A. Vitamin D: The Sunshine Vitamin. J PharmacolPharmacother 2012; 3(2):118–26. https://doi.org/10.4103/0976-500X.95506 15. Holick MF. Vitamin D Deficiency. New Engl J Med 2007; 357(3):266–81. https://doi.org/10.1056/NEJMra070553 16. Anglin RES, Samaan Z., Walter SD, McDonald SD. Vitamin D Deficiency and Depression in Adults: Systematic Review and Meta-analysis. Brit J Psychiat 2013; 202:100–7. 17. Sahay M, Sahay R. Rickets: Vitamin D Deficiency and Dependency. Indian J Endocrinol Metab 2012; 16(2):164–76. https://doi.org/10.4103/2230-8210.93732 18. Sizar O, Khare S, Goyal A, Gilver A. (2022) Vitamin D Deficiency. https://www.ncbi.nlm.nih.gov/books/NBK532266 (Last accessed October 2022) 19. Bordelon P, Ghetu MV, Langan RC. Recognition and Management of Vitamin D Deficiency. Am Fam Physician 2009; 15;80(8):841–6. Erratum in: Am Fam Physician 15;80(12):1357. 20. Amrein K, Scherkl M, Hoffmann M, et al. Vitamin D Deficiency 2.0: An Update on the Current Status Worldwide. Eur J Clin Nutr 2020; 74:1498–1513. https://doi.org/10.1038/s41430-020-0558-y 21. Moy, RJ., McGee, E., Debelle, GD., Mather, I., and Shaw, NJ. (2012) Successful public health action to reduce the incidence of symptomatic vitamin D deficiency. Arch Dis Child; 97(11):952-4. doi: 10.1136/archdischild-2012-302287.