The Effects Of Vitamin D3 Supplementation On Muscle Physical Performance And Vitamin Status In A Physically Active Population: A Randomized, Placebo-Controlled Blind Intervention Study

Objectives: This study aimed to determine if an eight-week supplementation of 50,000 IU of VitD3 will reverse deficiency in a physically active population.

Patients or Other Participants: A total of 29 physically active collegiate subjects (age =23.21±1.52 yrs, weight =70.66±14.23 kg, height=171.18 ± 9.03 cm) volunteered to participate in the study.

Intervention(s): Before completing pre-testing performance measures and beginning supplementation, venous blood samples to assess baseline serum 25(OH)D levels were collected from the cubital vein.

Main Outcome Measures: Serum 25(OH)D levels and muscle performance metrics (bench press, vertical jump, and 40m sprint) were analyzed to determine differences between pre-test and post-test data of both the control and treatment groups, respectively.

Results: A repeated measures ANOVA showed a significant increase in serum 25(OH)D levels after supplementation (p < .001) with a more prominent increase in the treatment group. These analyses indicate that there was no significant difference between the two treatment groups (VitD3 vs. placebo) at pre-treatment measurement, and post-treatment serum 25(OH)D status increased at a greater magnitude for Vitamin D (VitD) compared to the placebo group, who showed a relatively small change in serum 25(OH)D levels. Prior to D3 supplementation 19 of 29 total subjects (66%) had serum 25(OH)D concentrations considered to be deficient (<32 ng/ml).

Conclusions: Total serum 25(OH)D concentration significantly increased and eliminated pathological deficiency in the supplementation group after eight weeks of supplementation with 50,000 IU of VitD3.  Muscle performance metrics increased over the treatment period but were not significantly increased between treatment and control.