Vitamin D

The Backbone of Health

Of all the vitamins people have access to, vitamin D is one of the more well known. Whether people think about vitamin D in terms of sun exposure, bone strength, or foods, the majority of the population knows about this particular vitamin. However, people may be unaware of the importance of vitamin D and its critical link to musculoskeletal health.1 In the United States, around 41.6% of adults are deficient in vitamin D, and in the world, around 1 billion people have low vitamin D levels across all ethnicities and age groups.2 In terms of spine health, a study conducted by Kim et al highlighted that 74.3% of patients with a diagnosis of lumbar spinal stenosis were deficient in vitamin D.3 This particular study underscored the importance of vitamin D’s role in musculoskeletal health as the authors found greater pain was linked to low vitamin D levels and existing osteoporosis.

Vitamin D can be described as a critical nutrient for the establishment and maintenance of human bone health.4,5 In terms of maintenance, the vitamin is crucial in protecting against cancer, osteoarthritis, cardiovascular disease, and diabetes.6 Improving immune system function, muscle function, and balance can also be attributed to the role of vitamin D.6 Additionally, spine surgeons have found vitamin D to be essential for bone health and maintaining calcium balance in the body.6 By exploring the importance of vitamin D in the human body we can acquire a deeper understanding of how deficiency affects spine health and thus identify possible interventions.

Overview of Vitamin D

As noted previously, vitamin D is a critical mineral for the human body. Vitamin D is involved in various aspects of helping the body, but some of its main functions are to assist with calcium absorption and bone mineralization.6 Literature shows that calcium is absorbed from the small intestine when vitamin D is present.7 Absorption of calcium is critical to allow for adequate mineralization of the bone.7 Vitamin D heightens the efficacy of this absorption to help the overall function of the human body.7 On the other hand, bone mineralization is also highly important in regards to bone mineral density (BMD). Low bone mineral density can mean the presence of osteoporosis, which has the ability to lead to a greater risk of spine fractures.8 A healthy level of bone mineral density is good not just for spine health but overall bone health. Deficiency of vitamin D can even cause decreased immune function or autoimmune conditions.9 There are various ways to keep a healthy level of vitamin D in the body at all times, and these options are expanded upon later in this article.

Spine Health and the Role of Vitamin D

Vitamin D has a strong correlation to maintaining the integrity of various aspects of the human body, including the spine. Patients lacking in the vitamin can be predisposed to a heightened risk for worse clinical outcomes postoperatively.4 This may be due to the fact that when people lack vitamin D, their bones are weaker and they have lower bone density and lower calcium absorption.6,7 Thus, it is critical to maintain one’s bone health, thereby preserving spine health in the process. Maintaining spinal health leads to an increase in positive postoperative surgical outcomes and greater spinal stability.6 To maintain one’s spine health, the risk of fractures, deformities, and degenerative spine conditions must be minimized, and vitamin D can assist with all of this.

Vitamin D Deficiency

Vitamin D deficiency can be identified by various clinical risk factors such as deficient dietary intake to meet the body’s nutritional needs combined with restricted sun exposure.10 Additionally, gastrointestinal, hepatic, and renal conditions can lead to vitamin D deficiencies.10 Low vitamin D levels can result in bone loss due to reduced absorption of calcium in the intestine.10 Therefore, clinicians should regularly test for vitamin D deficiency in patients presenting with musculoskeletal pain and generalized weakness.10 Particularly, those with low bone mineral density, a history of low-impact skeletal fractures, or an increased risk of falling should be evaluated for vitamin D deficiency, as treatment can help reduce the risk of skeletal fractures.10 A randomized controlled trial found supplementation of vitamin D reduced the number of falls by around 50% among elderly women.11

Assessing vitamin D levels is crucial to determine whether there are deficiencies. Vitamin D obtained from our diets or sunlight exposure is rapidly converted to 25(OH)D, with a small amount becoming the active form, 1,25(OH)2D.10 Levels of 1,25(OH)2D are not measured to diagnose hypovitaminosis D because of its short half-life,12 and the body increases parathyroid hormone production in response to low vitamin D levels to help regulate calcium.10 Notably, this can keep calcium levels normal in blood tests and makes 25(OH)B a more reliable indicator of vitamin D status.10 Vitamin D deficiency is defined as 25(OH)D levels below 20 ng/mL and vitamin D insufficiency ranges from 2129 ng/mL of detected 25(OH)D.12 If patients are presenting with chronic back pain, it is important to consider testing for vitamin D deficiency. Maintaining an optimal level of 25(OH)D can support spinal health and potentially alleviate pain associated with underlying bone weakness.13

Prevention and Management

By addressing vitamin D deficiency through proper nutrition or supplementation, chronic pain, including low back pain, may be alleviated. Research has shown that an insufficient uptake of vitamin D and calcium in the diet is strongly linked to chronic low back pain, particularly in women.14 Omega-3 polyunsaturated fatty acids have been found to significantly reduce pain levels, specifically in patients with rheumatoid arthritis.14 Vitamin D can be obtained through dietary sources, sunlight, and supplements.15 Some of the few foods rich in vitamin D include oily or fatty fish, egg yolk, cod liver oil, and fortified foods such as milk and cereal.15,16

For adults, the recommended daily intake of vitamin D is 600-800 IU/day.15 To prevent falls and fractures in adults older than 65 years, the American Geriatric Society (AGS) and the National Osteoporosis Foundation (NOF) suggest higher intakes of 800-1000 IU per day.15,17 If daily intake is not met, supplementation is recommended. Vitamin D supplementation is in the form of cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2).18 A systematic review comparing the efficacy of each supplement concluded that cholecalciferol, or vitamin D3, had greater improvements in vitamin D status in individuals by raising serum 25(OH)D concentrations.18 Along with diet and supplementation, another source of vitamin D is ultraviolet (UV) sun radiation. Srivastava et al recommended 5 to 30 minutes of sunlight exposure at least twice a week without sunscreen, which blocks the effective production of vitamin D without UVB ray absorption from the body.19 Sunscreen should be applied at appropriate SPF levels after the short recommended time frame in the sun.19 It is important to maintain our vitamin D levels through sufficient dietary intake, vitamin D supplementation, and daily walking. 20 These practices contribute to stronger bones and greater spine health, reducing the risk of fractures associated with vitamin D deficiency.

Special Considerations for Spine Surgery

Ko et al analyzed clinical outcomes following lumbar spine surgery in patients with vitamin D deficiencies and divided cohorts based on whether they were taking supplementation for vitamin D.21 The outcome measures included the Oswestry Disability Index, the 36-item Short Form Survey (SF-36) Mental Component Score (MCS), and the SF-36 Physical Component Score (PCS).21 There were no significant differences found in preoperative scores; however, at the 1-year and 2-year postoperative follow-ups, patients who were not taking vitamin D supplementation reported significantly worse ODI, SF-36 MCS, and SF-36 PCS scores.21 Ko et al suggested checking vitamin D levels preoperatively and prescribing vitamin D supplementation to help long-term postoperative outcomes such as quality of life.21

Conclusion

Vitamin D plays a crucial role in maintaining spinal health by supporting bone density and reducing the risk of fractures. As mentioned previously, if patients are experiencing chronic back pain, it may be due to vitamin D deficiency. Therefore, it is important to regularly test vitamin D levels to address any deficiencies proactively. To maintain healthy vitamin D levels, it is necessary to maintain a healthy diet filled with omega-3 polyunsaturated fatty acids such as fish and fortified foods. Additionally, getting regular and safe sun exposure is crucial for increasing vitamin D levels. The recommended daily intake of vitamin D is 600-800 IU/day for adults, supplementation is recommended to achieve the desired amount. Maintenance of vitamin D levels is particularly important if undergoing spinal surgery for lumbar spinal stenosis. Research shows taking supplementation for vitamin D levels results in significantly better outcomes in physical health, mental health, and disabilit y scores compared to patients who do not. Recognizing the role of vitamin D can be transformative in terms of maintaining spine health and improving overall quality of life.

References

1. Forrest KY, Stuhldreher WL. Prevalence and correlates of vitamin D deficiency in US adults. Nutr Res . 2011;31(1):48-54.

2. Palacios C, Gonzalez L. Is vitamin D deficiency a major global public health problem? J Steroid Biochem Mol Biol. 2014;144(Pt A):138-145.

3. Kim TH, Lee BH, Lee HM, et al. Prevalence of vitamin D deficiency in patients with lumbar spinal stenosis and its relationship with pain. Pain Physician. 2013;16(2):165-176.

4. Bajaj A, Shah RM, Goodwin AM, Kurapaty S, Patel AA, Divi SN. The role of preoperative vitamin D in spine surgery. Curr Rev Musculoskelet Med. 2023;16(2):48-54.

5. Stoker GE, Buchowski JM, Bridwell KH, Lenke LG, Riew KD, Zebala LP. Preoperative vitamin D status of adults undergoing surgical spinal fusion. Spine (Phila Pa 1976). 2013;38(6):507-515.

6. Mayo BC, Massel DH, Yacob A, et al. A review of vitamin D in spinal surgery: deficiency screening, treatment, and outcomes. Int J Spine Surg. 2020;14(3):447-454. Published 2020 Jun 30. doi:10.14444/7059

7. Khazai N, Judd SE, Tangpricha V. Calcium and vitamin D: skeletal and extraskeletal health. Curr Rheumatol Rep. 2008;10(2):110-117.

8. Wu M, Du Y, Zhang C, et al. Mendelian randomization study of lipid metabolites reveals causal associations with heel bone mineral density. Nutrients. 2023;15(19):4160.

9. Johnson CR, Thacher TD. Vitamin D: immune function, inflammation, infections and auto-immunity. Paediatr Int Child Health. 2023;43(4):29-39.

10. Kennel KA, Drake MT, Hurley DL. Vitamin D deficiency in adults: when to test and how to treat. Mayo Clin Proc. 2010;85(8):752-758.

11. Bischoff HA, Stahelin HB, Dick W, et al. Effects of vitamin D and calcium supplementation on falls: a randomized controlled trial. J Bone Miner Res. 2003;18:343-351.

12. Holick MF. Vitamin D status: measurement, interpretation, and clinical application. Ann Epidemiol. 2009;19(2):73-78.

13. Cai C. Treating vitamin D deficiency and insufficiency in chronic neck and back pain and muscle spasm: a case series. Perm J. 2019;23:18-241.

14. Al-Rawaf HA, Gabr SA, Alghadir AH. Vitamin D deficiency and molecular changes in circulating microRNAs in older adults with lower back pain. Pain Res Manag. 2021;2021:6662651.

15. Chang SW, Lee HC. Vitamin D and health - the missing vitamin in humans. Pediatr Neonatol. 2019;60(3):237-244.

16. Nagaria TD, Shinde RK, Shukla S, Acharya S, Acharya N, Jogdand SD. The sunlight-vitamin D connection: implications for patient outcomes in the surgical intensive care unit. Cureus. 2023;15(10):e46819.

17. American Geriatrics Society Workgroup on Vitamin D Supplementation for Older Adults. Recommendations abstracted from the American Geriatrics Society Consensus Statement on Vitamin D for Prevention of Falls and Their Consequences. J Am Geriatr Soc. 2014;62(1):147-152.

18. Tripkovic L, Lambert H, Hart K, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr. 2012;95(6):1357-1364.

19. Srivastava SB. Vitamin D: do we need more than sunshine? Am J Lifestyle Med. 2021;15(4):397-401.

20. Ohta H, Kuroda T, Onoe Y, et al. The impact of lifestyle factors on serum 25-hydroxyvitamin D levels: a cross-sectional study in Japanese women aged 19-25 years. J Bone Miner Metab. 2009;27(6):682-688. doi:10.1007/s00774-009-0095-1

21. Ko S, Chae S, Choi W, Kwon J, Choi JY. The effectiveness of vitamin D supplementation in functional outcome and quality of life (QoL) of lumbar spinal stenosis (LSS) requiring surgery. J Orthop Surg Res . 2020;15(1):117. doi:10.1186/s13018-020-01629-2

Contributors:

Sloane Ward, BS

Shriya Patel, BS

Kern Singh, MD

From the Department of Orthopaedic Surgery at UC Davis School of Medicine in Sacramento, California.