Abstract
Vitamin D is important for musculoskeletal health, yet deficiencies remain prevalent among individuals with limited sun exposure. This study assessed serum 25-hydroxyvitamin D (25(OH)D) levels and their association with muscle discomfort in Malay female indoor workers. A total of 100 participants (aged 18-55 years) were recruited. Data on dietary vitamin D intake, sun-protective behaviours and muscle discomfort were collected using questionnaires. UVB exposure was assessed with polysulfone badges, and skin colour was measured with a reflectance spectrophotometer. Serum 25(OH)D levels were analysed via enzyme-linked immunoassay, with deficiency defined as < 30 nmol/L and insufficiency as ≥ 30-50 nmol/L. The median serum 25(OH)D level was 29.0 nmol/L (IQR: 10.0), with 54% classified as deficient and 36% as insufficient. Most participants (85%) had skin type II, and 93% did not meet dietary vitamin D recommendations. Limited UVB exposure (0.07 ± 0.06 SED/d) was recorded, with most participants exposing only their faces and hands. Muscle discomfort was commonly reported, particularly in the neck (90%), shoulders (88%) and lower back (79%). Serum 25(OH)D levels correlated negatively with muscle discomfort (r = -0.20; p = 0.04) and positively with dietary intake (r = 0.43, p < 0.001) and physical activity (r = 0.45, p < 0.001). Linear regression identified dietary vitamin D intake (β = 0.59, p < 0.001) and physical activity (β = 0.25, p = 0.002) as significant predictors of serum 25(OH)D levels. Multifaceted public health strategies addressing dietary supplementation, food fortification, safe sun exposure and physical activity are essential to improve vitamin D status and musculoskeletal health in this population.