Vitamin D Deficiency in Young Elite Soccer Players Residing Permanently in Regions above 55 Degrees North Latitude

Abstract

Background: Although the importance of maintaining optimal vitamin D levels is wellrecognized, vitamin D deficiency among athletes remains prevalent, particularly in regions located above 40 degrees north latitude. The study aimed to evaluate weekly cholecalciferol supplementation in correcting vitamin D deficiency in young soccer players.

Methods: The study involved 49 young soccer players permanently residing above 55 degrees north latitude with 25-hydroxy-vitamin D (25[OH]D) deficiency, randomized into an experimental group (N=25; mean age, 13.0±2.78 years) and a control group (N=24; mean age, 12.3±3.14 years). Participants in the experimental group received 15,000 IU of cholecalciferol once a week for six weeks. Blood samples were collected twice in February and May: before and after the intervention. Serum levels of 25(OH)D, calcium, ionized calcium, phosphorus, and parathyroid hormone using mass spectrometry have been measured.

Results: Baseline serum 25(OH)D levels were similar in both groups (15.59±2.66 ng/mL vs. 15.56±2.30 ng/mL; P>0.05). Post-intervention, levels rose to 30.25±5.17 ng/mL in the experimental group and 20.59±5.56 ng/mL in the control group, with significantly greater improvement in the experimental group (P<0.001). By the end, 60% of the experimental group reached normal 25(OH)D levels, compared to just 4.17% (N=1) in the control group. Other hematological parameters showed no significant intergroup differences (P>0.05).

Conclusions: A six-week course of 15,000 IU weekly cholecalciferol effectively and safely corrects 25(OH)D deficiency in young soccer players residing permanently in regions above 55 degrees north latitude, with minimal impact from spring outdoor training.

Keywords: Dietary supplements; Vitamin D; Vitamin D deficiency.