The role of Vitamin D in muscle health

Introduction: More Than Just a Vitamin

Vitamin D, often referred to as the “sunshine vitamin”, is in fact a true hormone essential for the proper functioning of the human body. Beyond promoting calcium deposition in bones — ensuring their strength and density — it also enhances the absorption of phosphorus, a key mineral for skeletal health.
In recent years, multiple studies have highlighted the pivotal role of vitamin D in supporting immune defenses and overall wellbeing.¹

To exert its biological effects, vitamin D binds to specific receptors (VDRs) distributed across many tissues, activating crucial cellular processes.²
Despite its synthesis through ultraviolet B (UVB) exposure, several factors — such as age, use of sunscreen, skin pigmentation, latitude, and sedentary lifestyle — can significantly limit endogenous production. Consequently, vitamin D deficiency has become a widespread global public health concern.

Vitamin D Metabolism

Vitamin D exists in two main forms:

• Vitamin D₂ (ergocalciferol): of plant origin
• Vitamin D₃ (cholecalciferol): of animal origin or synthesized in the skin

After dietary intake or cutaneous synthesis, both forms are converted in the liver into 25-hydroxyvitamin D (25(OH)D), the storage form and the main biomarker of vitamin D status.
Subsequently, in the kidneys, 25(OH)D is hydroxylated to calcitriol (1,25(OH)₂D), the biologically active form.³

Vitamin D₃ is naturally found in fatty fish (salmon, mackerel, herring), cod liver oil, and egg yolk. However, dietary intake alone is often insufficient to meet daily requirements, making vitamin D supplementation a common and effective strategy.

Vitamin D Deficiency: Causes

Vitamin D deficiency (VDD) is defined by serum 25(OH)D concentrations below 20 ng/mL (50 nmol/L), while levels between 21 and 29 ng/mL indicate insufficiency.

Common causes include:

• Limited sun exposure (indoor lifestyle, northern latitudes, winter season)
• Low dietary intake
• Intestinal malabsorption (celiac disease, Crohn’s disease)
• Aging, which reduces cutaneous synthesis
• Obesity, leading to sequestration of vitamin D in adipose tissue

Globally, it is estimated that over one billion people are affected by vitamin D deficiency, particularly the elderly and those living in regions with limited sunlight exposure.⁴

Vitamin D and Muscle Function

Beyond its role in bone health, vitamin D exerts important biological effects on skeletal muscle tissue. Muscle weakness is a well-documented clinical symptom in individuals with vitamin D deficiency, often associated with reduced physical performance and an increased risk of falls.

Skeletal muscle cells (myocytes) express vitamin D receptors (VDRs), through which calcitriol exerts its biological activity. This interaction triggers several key processes⁵:

• Promotion of muscle cell proliferation and differentiation
• Development of type II muscle fibers
• Enhancement of muscle contractile capacity

Clinical evidence shows that low vitamin D levels are associated with sarcopenia (loss of muscle mass) in older adults, while supplementation in deficient individuals can improve muscle strength and function, depending on dose, duration, and baseline status.

Vitamin D and sports performance

In the context of athletic performance, maintaining optimal vitamin D status is critical for neuromuscular function, balance, coordination, recovery, and injury prevention.

Vitamin D supports:

• Neuromuscular efficiency
• Balance and coordination
• Muscle recovery
• Reduced injury risk

Monitoring serum vitamin D levels is particularly recommended for athletes who train indoors or in winter. However, supplementation should be personalized, avoiding excessive dosages: the U.S. National Academy of Medicine recommends an upper intake limit of 4,000 IU/day. Excessive doses may trigger feedback mechanisms that reduce the vitamin’s biological effectiveness.⁶

Vitamin D and Statins: Emerging Perspectives in Muscle Health

An emerging area of research explores the connection between vitamin D and statin-associated muscle symptoms (SAMS). Statins, widely prescribed for cardiovascular prevention, can cause muscle-related adverse effects — such as pain, cramps, or weakness — in approximately 10–20% of patients.⁷

Several studies suggest that vitamin D deficiency may predispose individuals to statin-induced myopathy by worsening muscular function. Supplementation with vitamin D in deficient patients has been shown to reduce the incidence of SAMS and improve treatment tolerability.⁸

Sucrosomial® Vitamin D3 : Innovation in Nutritional Supplementation

Vitamin D deficiency is commonly addressed through daily, weekly, or monthly supplementation. However, intestinal absorption can be suboptimal, reducing the efficacy of standard formulations.

An innovative solution is represented by Sucrosomial® Vitamin D3, available in Sidevit® D3 2000 IU. Thanks to a phospholipid and sucrose-ester matrix, Sucrosomial® Technology protects vitamin D₃ from degradation and enhances its intestinal absorption, leading to significantly higher circulating 25(OH)D levels compared to conventional formulations.⁹

Vitamin D and Muscle Health: A Synergistic Link Worth Preserving

Vitamin D is a key factor in muscle health, contributing to strength, endurance, and optimal function. Its supplementation not only supports bone integrity and athletic performance, but also helps prevent injuries and improve tolerance to statin therapy.

With the advent of Sucrosomial® Vitamin D3, supplementation takes a step forward—ensuring faster and more efficient absorption, and offering a valuable strategy for athletes, older adults, and anyone at risk of vitamin D deficiency.

BIBLIOGRAPHY

1. Aranow C.; Vitamin D and the Immune System. J Investig Med. 2011 Aug; 59(6): 881–886.
2. Janoušek J, et al. Vitamin D: sources, physiological role, biokinetics, deficiency, therapeutic use, toxicity, and overview of analytical methods for detection of vitamin D and its metabolites. Crit Rev Clin Lab Sci. (2022) 59:517–54.
3. Bikle Daniel D. Vitamin D metabolism, mechanism of action, and clinical applications. Chem Biol. (2014) 21:319–29.
4. Roomi MA, et al. Hypovitaminosis D and its association with lifestyle factors. Pak J Med Sci. 2015 Sep-Oct;31(5):1236-40. doi: 10.12669/pjms.315.7196. PMID: 26649021; PMCID: PMC4641290.
5. Dominguez LJ, Veronese N, Ragusa FS, Baio SM, Sgrò F, Russo A, Battaglia G, Bianco A, Barbagallo M. The Importance of Vitamin D and Magnesium in Athletes. Nutrients. 2025 May 13;17(10):1655. doi: 10.3390/nu17101655. PMID: 40431395; PMCID: PMC12114196.
6. Ross AC, Manson JE, Abrams SA, Aloia JF, Brannon PM, Clinton SK, Durazo-Arvizu RA, Gallagher JC, Gallo RL, Jones G, Kovacs CS, Mayne ST, Rosen CJ, Shapses SA. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab. 2011 Jan;96(1):53-8. doi: 10.1210/jc.2010-2704. Epub 2010 Nov 29. PMID: 21118827; PMCID: PMC3046611.
7. Abd TT, Jacobson TA. Statin-induced myopathy: a review and update. Expert Opin Drug Saf. 2011 May;10(3):373-87. doi: 10.1517/14740338.2011.540568. Epub 2011 Feb 23. PMID: 21342078.
8. Fadah K, Mares A, Lange RA. Statin-Associated muscle symptoms and vitamin D supplementation. Curr Opin Cardiol. 2025 Jul 1;40(4):215-220. doi: 10.1097/HCO.0000000000001222. Epub 2025 Apr 24. PMID: 40183368; PMCID: PMC12147742.
9. Bano A, et al. A comparative absorption study of sucrosomial^® orodispersible vitamin D3 supplementation vs. a reference chewable tablet and soft gel capsule vitamin D3 in improving circulatory 25(OH)D levels in healthy adults with vitamin D deficiency-Results from a prospective randomized clinical trial. Front Nutr. 2023 Aug 17;10:1221685.