Vitamin D supplementation attenuates oxidative stress in paraspinal skeletal muscles in patients with low back pain.

PURPOSE: The aim of the study was to evaluate markers of oxidative stress and vitamin D receptor in paraspinal muscles in low back pain patients with vitamin D deficiency, with normal level of vitamin D, and after 5 weeks of vitamin D supplementation.

METHODS: Patients were divided into three groups: supplemented (SUP) with vitamin D, placebo with normal concentration of vitamin D (SUF), and the placebo group with vitamin D deficiency (DEF). The concentration of serum vitamin D was measured before and after the supplementation with vitamin D (3200 IU/ day for 5 weeks). Markers of lipid and protein peroxidation, the activity of antioxidant enzymes, and protein content of vitamin D receptor was determined in multifidus muscle of patients.

RESULTS: Vitamin D supplementation increased serum level of 25(OH)D3 (p < 0.001). In paraspinal muscle level of 8-isoprostanes and protein carbonyls was higher in DEF group as compared to the SUP group (p < 0.05). Antioxidant enzyme activity and vitamin D receptor in paraspinal muscle altered between the groups with different serum vitamin D concentration. The cytosolic superoxide dismutase and glutathione peroxidase activities were significantly higher in DEF group as compared to the SUP group (p < 0.05).

CONCLUSIONS: An attenuation of markers of free radical damage of lipids and proteins was observed in participants supplemented with Vitamin D. Antioxidant enzyme activities in skeletal muscle differ among patients with different serum vitamin D concentration. Monitoring oxidative stress and VDR protein content might be useful for future studies on the mechanism(s) of vitamin D action in muscle.