The Effect of Ongoing Vitamin D and Low-Fat Milk Intake on Bone Metabolism in Female High-School Endurance Runners

Abstract

BackgroundVitamin D and calcium are essential nutrients for bone health. In addition, vitamin D suppresses inflammatory cytokines and increases bone resorption. Therefore, improvements in bone health by calcium and vitamin D supplementation have the potential to not only improve calcium metabolism but also suppress inflammation associated with exercise training. The purpose of this study was to determine whether ongoing vitamin D supplementation and low-fat milk intake by female high-school endurance runners would improve bone metabolism by suppressing inflammatory cytokines and the parathyroid hormone (PTH).MethodsTwenty female high-school runners were assigned to a vitamin D supplement and low-fat milk intake group (MKD) or a control group (CON). Participants in the MKD group consumed a vitamin D supplement (1,000 IU/day) and low-fat milk (Ca 315 mg/day) for 6 months. Bone mineral density measurements, blood samples, and questionnaires (regarding menses and diet) were carried out. The UMIN Clinical Trials Registry number is UMIN000027854.ResultsThe 25-hydroxyvitamin D (25(OH)D) concentration in MKD was sustained and PTH concentration was decreased regardless of the state of menses. The correlation coefficients of 25(OH)D or PTH concentrations and bone metabolism markers were analyzed by partial correlation coefficient via adjusting the model for frequency of menses. CTX and 25(OH)D concentration were significantly and inversely correlated at baseline (r = -0.61, P < 0.01), 3 months (r = -0.54, P = 0.02), and 6 months (r = -0.53, P = 0.02). CTX and PTH were significantly and positively correlated at 3 months (r = 0.63, P < 0.01) and 6 months (r = 0.52, P = 0.02). The bone alkaline phosphatase (BAP)/CTX ratio and 25(OH)D concentration were significantly and positively correlated at 3 months (r = 0.59, P = 0.01) and 6 months (r = 0.56, P = 0.01). The BAP/CTX ratio and PTH were significantly and inversely correlated at 3 months (r = -0.59, P = 0.01) and 6 months (r = -0.58, P < 0.01).ConclusionsThis study suggested that vitamin D and low-fat milk supplementation improves bone metabolism by sustaining the 25(OH)D concentration and decreasing the PTH concentration in female high-school endurance runners regardless of the state of menses.

The Effect of Vitamin D Consumption on Pro-Inflammatory Cytokines in Athletes: A Systematic Review of Randomized Controlled Trials

“…In this research, the results indicated that 12 weeks of vitamin D supplementation, despite optimizing vitamin D concentration, had no significant effect on IL-8, hs-CRP, and TNF-α levels in athletes. These findings regarding TNF-α levels are in agreement with the observations of Lewis [ 37 ], Zebroska [ 34 ], and Ikedo [ 36 ]. These results are inconsistent with the proposed association between vitamin D and inflammation in athletes and healthy adults [ 21 ].…”

“…Lewis [ 37 ] indicated that an insignificant relationship was observed between the level of vitamin D and inflammatory cytokines. On the other hand, in a study conducted on a group of university athletes and recreational runners, the amount of α-TNF decreased after vitamin D consumption [ 21 ], while other studies have found a negative correlation between 25 (OH)D concentration and TNF-α levels during a 24 h recovery period [ 34 , 36 ]. In addition, the levels of inflammatory markers in soccer players were investigated [ 39 ].…”

“…The vitamin D group consumed 10,000 IU daily for 2 weeks [ 35 ]. In addition, in another study, which was conducted on female endurance runners for 6 months, the subjects were divided into two equal groups of 10 subjects (placebo and vitamin D supplemented) and they took 1000 IU of vitamin D daily, consumed with low-fat milk [ 36 ]. Moreover, in the study of Lewis [ 37 ], which was conducted on swimmers and divers, 4000 IU of vitamin D supplement (19 participants) and a placebo (13 participants) were distributed daily.…”

Concurrent Bilateral Anterior Tibial Stress Fractures and Vitamin D Deficiency in an Adolescent Female Athlete: Treatment With Early Surgical Intervention

“…Increased consumption of calcium, vitamin D, and protein may play a preventative role against stress fracture development. (5, 6, 14, 17–20) Prospective studies including only females showed that increased intake of calcium and vitamin D supplements, dietary calcium, or dairy products (calcium, vitamin D, and protein) were associated with decreased incidence of stress fractures (13, 21, 22).…”

The effects of concurrent training (aerobic-resistance) and milk consumption on some markers of bone mineral density in women with osteoporosis

“…A supplement containing 300 mg per day of calcium cannot reduce bone loss in the lumbar spine and greater Trochanter, but 600–900 mg per day can be beneficial. Also, Ikedo et al [43] on Long-distance running women showed that taking vitamin D supplementation and low-fat milk for 6 months improved bone metabolism by maintaining the concentration of 25OH-D and decreasing concentration of PTH and reducing inflammatory cytokines. Furthermore, Rajatanavin et al [38] stated that calcium supplementation of 500 mg per day can reduce bone turnover and decrease bone mass in older women.…”