Vitamin D status in Polish women with endocrine and osteoporotic disorders in relation to diet, supplement use and exposure to ultraviolet radiation

Background In Europe, the rate of 25(OH)D deficiency is considered high. Thus, it seems necessary to conduct population-based studies to fully assess vitamin D deficiency in various groups of patients. Objectives To evaluate serum 25(OH)D levels and the frequency of deficiency in women in Poland with endocrine and osteoporotic disorders. The influences of diet, use of vitamin/mineral supplementation and exposure to ultraviolet (UVB) radiation on vitamin D status in women with metabolic disorders were also examined. Material and methods The patient group consisted of 223 women aged 19-81 years diagnosed with endocrine and/or osteoporotic disorders. The control group consisted of 108 clinically healthy women aged 26-72 years. Serum 25(OH)D concentration was assessed using a chemiluminescent immunoassay (CLIA). An ad hoc questionnaire was used to assess the participants' exposure to UVB radiation. Food intake was assessed using a three-day 24-hour questionnaire interview. Results The following groups showed significantly higher 25(OH)D levels: women taking vitamin D supplements compared to women not taking vitamin D supplements (29.3 ±3.2 compared to 19.5 ±3.7 ng/mL, p = 0.0024); premenopausal women compared to postmenopausal women (28.9 ±5.2 compared to 21.5 ±4.5 ng/mL, p = 0.0021); women who visited sunny countries in the last 6 months compared to women who did not (28.1 ±3.1 ng/mL compared to 24.5 ±5.3 ng/mL, p = 0.0031); and normal weight or overweight women (according to body mass index (BMI)) compared to obese women (27.4 ±4.5 ng/mL compared to 22.3 ±4.7 ng/mL, p = 0.0431). In addition, 25(OH)D concentration correlated with total dietary vitamin D intake in the patient group (R = 0.17, p = 0.0021). Of all examined food groups, fish consumption affected serum 25(OH)D levels in patients (R = 0.20, p = 0.0421) and controls (R = 0.29, p = 0.0002). Consumption of fish products contributed to statistical differences between the patient group (R = 0.17, p = 0.0072) and healthy subjects (R = 0.19, p = 0.0032). Conclusions The most crucial factors influencing vitamin D status in the studied women were regular fish consumption, spending holidays in sunny destinations and regular intake of vitamin D preparations.