• Vitamin D: Much More than Bone Health
    Learn about the other health and performance benefits of this powerful nutrient. From the NSCA's Performance Training Journal.
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  • Vit D more than bone healthIn the past couple of years vitamin D has received a lot of attention regarding how it impacts overall health. However, many fitness professionals still do not realize vitamin D goes well beyond bone health and “female” clients.

    What is Vitamin D?
    Vitamin D is a secosteroid; it functions as a modulator for as many as 1,000 genes involved in cellular growth, immune function and protein synthesis as well as intestinal calcium absorption and osteoclastic activity (1,3). Vitamin D is related to health and athletic performance through the following processes (1,2,3):
    • Calcium homeostasis and bone health 
    • Immunity 
    • Inflammatory modulation 
    • Skeletal muscle function 
    • Potential to impact health, training and performance of athletes 
    Not Just a “Female” Issue
    One research study found that 72 out of 89 football players in the National Football League (NFL), with an average age of 25, had inadequate levels of vitamin D. Vitamin D levels range from 32–100 ng/dl on most lab reports. Serum 25(OH) D concentration is the best indicator of vitamin D status and 40–70 ng/dl are considered optimal levels (5,6).

    Out of these 89 NFL football players, 27 players had deficient levels (20 ng/dl) and 45 had insufficient vitamin D levels (20–31.9 ng/dl). Sixteen out of the 27 players suffered a muscle injury with an average vitamin D level of 19.9 ng/dl.

    Vitamin D conversion comes mainly from sunlight and happens around mid-day when the sun is highest overhead. Many people are out in the morning or evening but not as much during the lunch hour. Also, depending on the region you live vitamin D conversion during the winter months may be severely limited (e.g., latitudes above or below 35–37 degrees north or south have no conversion). Another contributing factor is the increased usage of sunscreen and the push to wear it at all times.


    How Much Sun is Needed?
    Anywhere from 5–30 min per day of sun exposure is suggested (5). The lighter the skin color one has, the less time is needed in the sun to absorb vitamin D; the darker the skin color one has requires a longer exposure time for optimal conversion (5).

    Food Sources and Guidelines
    The goal is to acquire 200 IU of vitamin D per day from food. Fatty fish (e.g., mackerel, salmon, sardines, tuna) fortified milk, egg yolks, fortified orange juice and certain brands of margarine, yogurt and cereal are reputable sources for vitamin D (4).

    Overall Recommendations
    • Does not matter if you are a female or male 
    • 200 IU of vitamin D per day through food 
    • Serum 25(OH) D between 40–70 ng/ml for optimal levels 
    • 5–30 min of sunlight per day pending on skin color and living location 
    • Individuals with limited sun exposure require 1,500–2,000 IU per day of vitamin D to maintain sufficient range. 
    It is suggested that coaches start asking their clients/athletes if they know their current vitamin D status due to the percentage of individuals who are not at optimal levels; in conjunction with, its importance on bone, immune, muscle and inflammatory systems.

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    About the Author:

    Dawn Weatherwax, CSCS, RD,CSSD, LD, ATC

    Dawn Weatherwax is a Registered/Licensed Dietitian with a specialty in Sports Nutrition and is the Founder of Sports Nutrition 2Go. She is also a Board Certified Specialist in Sports Dietetics, which is the premier professional sports nutrition credential in the United States. In addition, she is an athletic trainer and has earned the Certified Strength and Conditioning Specialist® (CSCS®) credential. Weatherwax is also the author of The Official Snack Guide for Beleaguered Sports Parents and The Complete Idiot’s Guide to Sports Nutrition. Weatherwax is an official speaker for the Gatorade Sports Science Institute and on the approval speaker list for the NCAA. She has also been featured on television shows including Good Morning America, MSNBC, Geraldo Rivera, and Fox News. Weatherwax is an active member in the American Dietetic Association (ADA), Sports, Cardiovascular, and Wellness Nutritionists Dietetic Practice Group (SCAN), American College of Sports Medicine (ACSM), National Strength & Conditioning Association (NSCA), National Athletic Training Association (NATA), and Greater Cincinnati Athletic Training Association (GCATA).

    REFERENCES →

    1. American Orthopedic Society for Sports Medicine (AOSSM) 2011 Annual Meeting: Abstract 46: Presented July 10, 2011.
    2. Cannell, JJ, Hollis, BW, Sorenson, MB, Taft, T, and Anderson, J. Athletic performance and vitamin D. Med Sci Sports Exerc 41: 1102–1110, 2009.
    3. Halliday, TM, Peterson, NJ, Thomas, JJ, Kleppinger, K, Hollis, B, et al. Vitamin D status in relation to diet, lifestyle habits and injury in college athletes. Med Sci Sports Exerc 43(2): 335–343, 2011.
    4. Holick, MF. Vitamin D deficiency. N Engl J Med 357: 266–281, 2007.
    5. Holick, MF, Binkley, NC, Bischoff-Ferrari, HA, Gordan, CM, Hanley, DA, Heaney, RP, Murad, NH and Weaver, CM. Evaluation, treatment and prevention of vitamin D deficiency: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 96(7): 1911–1930, 2011.
    6. Larson-Meyer, DE, and Willis, KS. Vitamin D and athletes. Curr Sports Med Rep 9(4): 220–226, 2010.

  • Disclaimer: The National Strength and Conditioning Association (NSCA) encourages the exchange of diverse opinions. The ideas, comments, and materials presented herein do not necessarily reflect the NSCA’s official position on an issue. The NSCA assumes no responsibility for any statements made by authors, whether as fact, opinion, or otherwise. 
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