Changes in Bone Turnover, Inflammatory, Oxidative Stress, and Metabolic Markers in Women Consuming Iron plus Vitamin D Supplements: A Randomized Clinical Trial
Abstract Background We aimed to investigate whether combination of vitamin D and iron supplementation, comparing vitamin D alone, could modify bone turnover, inflammatory, oxidative stress, and metabolic markers. Methods Women with hemoglobin (Hb)≤12.7 g/dL and 25OHD≤29 ng/mL vitamin D deficiency/insufficiency aged 18-45 years (n=100) were recruited into a trial to receive either 1000 IU/d vitamin D3 plus 27 mg/d iron (D-Fe) or vitamin D3 plus placebo supplements (D-P) for 12 weeks. Results In D-Fe group, significant decreases in red blood cells (RBC) (P=0.001), hematocrit (Hct) (P=0.004) and increases in mean corpuscular hemoglobin concentration (MCHC)(P=0.001), 25OHD (P<0.001), osteocalcin (P<0.001), high-density cholesterol (HDL) (P=0.041), and fasting blood sugar (FBS) (P<0.001) were observed. D-P group showed significant decreases of RBC (P<0.001), Hb (P<0.001), Hct (P<0.001), mean corpuscular volume (MCV) (P=0.004), mean corpuscular hemoglobin (MCH) (P<0.001), MCHC (P=0.005), serum ferritin (P<0.001), and low-density cholesterol (LDL) (P=0.016) and increases of 25OHD (P<0.001), osteocalcin (P<0.001), C-terminal telopeptide (CTX) (P=0.025), triglyceride (TG) (P=0.004), FBS (P<0.001), and interleukin-6 (IL-6) (P=0.001) at week 12. After the intervention, the D-P group had between-group increases in mean change in the osteocalcin (P=0.007) and IL-6 (P=0.033), and decreases in the RBC (P<0.001), Hb (P<0.001), Hct (P<0.001), MCV (P=0.001), compared to the D-Fe group. There were significant between-group changes in MCH (P<0.001), MCHC (P<0.001), ferritin (P<0.001), and serum iron (P=0.018). Conclusions Iron-vitamin D co-supplementation does not yield added benefits for improvement of bone turnover, inflammatory, oxidative stress, and metabolic markers; whereas, vitamin D alone may have some detrimental effects on inflammatory and metabolic markers.