Low Vitamin D Levels in NFL Players, Other Athletes

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One of the newest studies to focus on the importance of vitamin D suggests that low levels of the nutrient may increase the risk of sports-related muscle injuries, especially in NFL players. This research joins other findings pointing to a need to examine and address vitamin D insufficiency and deficiency not only in football players, but in other athletes as well.

Vitamin D promotes bone and athletes’ health

Several recent studies and reviews have focused on the issue of vitamin D deficiency and insufficiency in athletes. Because vitamin D is critical for optimal bone health and also plays a major role in inflammation, infectious disease, and muscle function, it is natural for athletes, trainers, and medical professionals to be concerned about achieving and maintaining adequate levels of this essential vitamin.

The most recent example of this concern comes from a study presented at the American Orthopaedic Society for Sports Medicine’s Annual Meeting in San Diego. Investigators evaluated the vitamin D levels of 89 NFL players from a single team. Lab testing of vitamin D was done in spring 2010 as part of the team’s routine pre-season evaluations.

Normal values of vitamin D were defined as greater than 32 ng/mL, and only 17 players (20%) were shown to have such levels. Eighty percent of the players had vitamin D insufficiency (20 to 31.9 ng/mL, 45 players) or vitamin deficiency (less than 20 ng/mL, 27 players). Sixteen NFL players had experienced a muscle injury, and their mean vitamin D level was 19.9 ng/mL.

According to Michael Shindle, MD, the study’s lead researcher and a member of Summit Medical Group, “African American players and players who suffered muscle injuries had significantly lower levels.” The mean vitamin D level in white players was 30.3 ng/mL, and it was 20.4 ng/mL in black players.

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Dr. Scott Rodeo, MD, co-chief of the Sports Medicine and Shoulder Service at the Hospital for Special Surgery, noted that “Screening and treatment of vitamin D insufficiency in professional athletes may be a simple way to help prevent injuries.”

In an earlier review, published in the July-August 2010 issue of Current Sports Medicine Review by researchers at the University of Wyoming, it was emphasized that “it is imperative that sports dietitians and physicians routinely assess vitamin D status and make recommendations” to help their athletes bring their serum 25(OH)D concentrations levels preferably to at least 40 ng/mL.

A subsequent study in the Clinical Journal of Sports Medicine examined the data on vitamin D insufficiency in 98 athletes and dancers (age range 20 to 30 years) in a sunny country. Vitamin D insufficiency was defined as a serum 25(OH)D concentration of less than 30 ng/mL. Seventy-three percent of the participants had vitamin D insufficiency, and insufficiency was greatest among dancers and basketball players (94% in each group).

Overall, vitamin D insufficiency was greatest among indoor versus outdoor sports (80% vs. 48%, respectively). The authors concluded that given the importance of vitamin D, athletes and dancers should be screened for vitamin D insufficiency and treated accordingly.

A February 2011 study measured vitamin D concentrations in 41 college athletes throughout an academic year. Researchers found that vitamin D concentrations in the spring were “correlated with frequency of illness” and noted that “insufficient vitamin D status may increase risk for frequent illness.”

Although most doctors believe a serum vitamin D value of 30 ng/mL is sufficient, it is not, according to the Vitamin D Council. The Council reports that evidence indicates the beneficial serum level of vitamin D is around 50 ng/mL or higher.

SOURCES:
American Orthopaedic Society for Sports Medicine
Constantini NW et al. Clinical Journal of Sports Medicine 2010 Sep; 20(5): 368-71
Halliday TM et al. Medicine and Science in Sports Medicine 2011 Feb; 43(2): 335-43
Larson-Meyer DE, Willis KS. Current Sports Medicine Reports 2010 Jul-Aug; 9(4): 220-26
Vitamin D Council
Photo source: Wikimedia Commons

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