Exercise as it relates to Disease/The effects of vitamin D deficiency in athletes

What is the background to this research?

Approximately 1 billion individuals of various ethnicities and age groups worldwide have low vitamin D levels. Due to the difference in lifestyle choices, individuals are spending more time indoors, missing the opportunity to naturally absorb Vitamin D through unprotected sunlight for 10 to 15 minutes, before 10 am or after 3 pm three to four times a week. Vitamin D plays a vital role in the body, as it orchestrates normal immune function, it further regulates the absorption of phosphorus and calcium.The study assesses the levels of vitamin D inadequacy in various athletes that participate in indoor and outdoor sports over different seasonal periods. The authors further assessed if the levels of vitamin D inadequacy poses a potential risk to athletes in regard to their geographic location that have significantly higher latitudes, age, use of sunscreen melanin content in the skin, time of sun exposure during the day and the extent of the athlete shading their skin, could have an effect on their Vitamin D absorption.

Where is the research from?

The study was conducted in Istanbul, Turkey from September 2014 to February 2015 in the Department of Sports Medicine Clinic, by Canan Gönen Aydın, Yaşar Mahsut Dinçel, Yavuz Arıkan, Süleyman Kasım Taş and Serdar Deniz. All the authors have released and published multiple studies and research journals. Although the study was not conducted in Australia, Australia has a prevalence of Vitamin D deficiency affecting approximately 23% (4 million) of the population according to 2011-2012 ABS findings. The majority of the authors work in the Department of Sports Medicine, Department of Orthopaedic and Traumatology as well as the Bone, and Joint disease Education and Research Hospital. The lead author has conducted extensive research in the sports medicine field, as this is his second study on how vitamin D level affects athletes’ performance. The authors of the article stated that there were no potential conflicts of interest in regard to the research conducted, composition and publication of the article.

What kind of research was this?

The research conducted was a combination of a cross sectional study and a meta-analysis. The study assessed both the outcome of Vitamin D deficiency and result which measured the exposure of sunlight in the selected participants. Within the study a meta-analysis was conducted as several statistical data from various studies were curated and further analysed in the study. It is suggested that further studies be conducted to evaluate vitamin D deficiency specifically in indoor and outdoor sporting activities, as there are limited studies in the selected criteria.

What did the research involve?

The study took place at the Sports Medicine Clinic which consisted of 555 elite level athletes, comprising of 326 females and 229 males ranging from ages 5 to 52 years, analysing their serum 25-hydroxyvitamin D concentration. The study assessed the difference of Vitamin D levels in indoor sports such as dancing, gymnastics and basketball, whilst the outdoor activities evaluated were football and athletics, conducted in different months determining if the synthesis of vitamin D decreased or increased due to the environment of exercise and seasonal period. The athletes were required to abstain from exercising twenty-four hours before they provided a non-fasted intravenous blood sample the morning before blood collection.

The authors analysed vitamin D measurements from past data, acquired from the medical achieve of the Sports Medicine Clinic. The study was not carried out as accurately as the objective has detailed. The methodology was not the best approach as the study omitted the data of pre-existing medical issues such as; inflammatory joint disease, malignancy, thyroid/parathyroid dysfunction, illicit drug use, neuromuscular disease and generalised cardiovascular disorders which could be a vital contributing factor to the results found. The is also a discrepancy in findings carried out by the author, as the results have been dependent based on past studies and further analysing previous result data.

The limitations of the study were due to the shortage of original methods and findings conducted by the authors. The majority of the study depends on pre-existing research as opposed to forming and orchestrating their own study for the athletes recruited. The athletes are only required to give blood samples to be assessed whilst there are no protocols such as a control group vs indoor vs outdoor sporting activity in place to accurately assess and compare the data. The authors declared that there were limitations in the study as they compared different results from various literature originating from other demographic locations, effectively skewing the results.

What were the basic results?

According to the research conducted by the authors an increase in vitamin D levels may result in several benefits in the muscular and skeletal systems of athletes. The concentration of protein synthesis and adenosine triphosphate (ATP) concentration in the muscle tissue increase due to increased physical performance, exercise capacity, muscular strength and jumping height and power exerted. The studies suggest that both children and adults have approximately 40 to 60 nanograms per millilitre of 25 hydroxyvitamin D [25(OH)D], as it is essential that is stored in their muscles and fat stores to have an adequate level for further use.

Findings suggest that the performance of the athletes working muscles gradually start to impair if the level of 25(OH)D is below 32 ng/ml. 25 (OH)D may not be readily available for the advance processing involved in the autocrine pathways, as the pathway is influence performance. With decreased levels the athletes are likely to experience hypotonia, muscle weakness, and prolonged muscle contraction. A lack of vitamin D in children can lead to bone deformities such as rickets, and in adults they are most likely to experience bone pain and muscle weakness caused by a condition called osteomalacia. The results suggest that vitamin D insufficiency is prevalent in Turkish athletes, as 19.5% of the athletes presented with vitamin D insufficiency in serum 25(OH)D between 21 to 30 ng/mL, and with vitamin D deficiency of 42.7% in (serum 25(OH)D, between 11 to 20 ng/mL, the authors concluded that there were no significant effects of vitamin d levels between males and females within the sports environment on mean vitamin D values. Furthermore, the study suggests that the serum25 (OH) D levels of indoor sports athletes were between 29.1 ± 17.8 ng/mL in autumn and 16.7 ± 10.3 ng/mL in winter.

What conclusions can we take from this research?

The study suggests that Vitamin D insufficiency is an issue that not only affects athletes, it also effects individuals of all ages and ethnicities worldwide, it further highlights the detrimental long-term health effects that will occur when inadequate levels of vitamin D are sustained for extended period of time. The authors made it evident that there was still further research and evaluation of studies that needed to be conducted to verify the findings. The authors suggested that winter had a negative impact on the levels of vitamin D, and athletes would need to ensure that they had adequate precautions in place to increase their intake to maintain optimum performance.

Practical advice

Furthermore, it would be highly suggestible that additional thorough studies be conducted on a controlled group of individuals across all sporting groups, assessing the risk factors and other parameters with a specific selection criterion to be tested under various protocols.

Further information/resources

Further resources and information of vitamin D can be found at:

• https://www.betterhealth.vic.gov.au/health/healthyliving/vitamin-d
• https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
• https://www.osteoporosis.org.au/vitamin-d