The "Sunshine" Vitamin:
Are You Getting Enough Vitamin D?

Vitamin D3 (Cholecalciferol) is essential for life and may be the most important supplement you need to add to your diet. Most athletes are Vitamin D deficient. Every tissue in the body needs Vitamin D and will not work correctly or optimally if you do not get enough. Research shows that Vitamin D has a central role in many vital body processes including:

  • Muscle Tissue Function
  • Brain Health
  • Protein and Hormone Synthesis
  • Cell Regeneration

Benefits of Vitamin D:

  • Improves Immune Function (Less Colds and Flu)
  • Decreases Risk of Many Diseases Including Cancers and Diabetes
  • Improves Muscular Function
  • Improves Brain Health and Cognitive Function
  • Improves Body Composition
  • Faster Recovery from Training and/or Injury
  • Improves Mood and Psychological Well Being
  • Reduces Injury Rates for Athletes

Vitamin D is technically not a vitamin, but a fat-soluble secosteroid; but like vitamins, deficiencies occur when the body does not get enough. Safe sun exposure is the best source of Vitamin D, but in most areas you cannot get enough Vitamin D most of the year and sun screen blocks 98% of Vitamin D synthesis. People with darker skin also do not synthesize as much from sun exposure, contributing to an epidemic of Vitamin D deficiency in certain ethnic groups. Dietary Vitamin D is therefore required to supplement your body’s synthesis and meet the demands, especially for athletes that are putting added stress on their bodies and would benefit from speeding up recovery time between practices and competition.

Vitamin D content in foods is not high enough to meet daily requirements and in many cases, the conservative RDA of 600 IU is enough to prevent major deficiency, but is not enough to reach the ideal range.

Ideal serum levels of Vitamin D are between 30-70 ng/mL (with the ideal level being approximately 50 ng/mL) as established by a blood test. According to the National Institutes of Health, serum levels of above 200 ng/mL are "potentially toxic". To reach this toxic level, consumption must be above 40,000 IU daily for an extended period; a dose much higher than recommended.

Our recommendation is to ideally get between 15-30 minutes of sun exposure daily, but this number is subject to change based on a variety or variables including latitude, altitude, weather, season, time of day, and skin color/ethnic background. On top of this, our busy schedules and participation in indoor activities may not allow us to realistically make a habit of this.

Signs and symptoms of Vitamin D deficiency in athletes are:

  • Frequent Illness
  • Muscle and Joint Pain
  • Fatigue
  • Stress Fractures
  • Increased Body Fat

Supplementing with 2,000 IU daily for most athletes, and 5,000 IU for indoor athletes, athletes with dark skin, and athletes living far north (in the northern hemisphere) is very safe and likely necessary for reaching ideal Vitamin D status. (Again, these numbers are applicable to most individuals, however if you want to get very precise, you should take a blood test to find your Vitamin D status and plan your supplementation strategy based on the results.)

There is emerging research relating Vitamin D levels and injury rates in athletes.

Seattle Sounders FC professional soccer team monitored Vitamin D status in relation to injury rates:

Athletes with >40 ng/ml Average 1.12 games missed
Athletes with < 30 ng/ml Average 2.92 games missed
1 Athlete consistently at 60 ng/ml 0 injuries in 3 years


0 Games Missed Average 44 ng/ml
1-2 Games Missed Average 34.76 ng/ml
3+ Games Missed Average 29.73 ng/ml

European soccer teams have found similar results.

Improved athletic performance and resistance to injury is great, but more importantly Vitamin D deficiency has been associated with a number of diseases. Dr. Cedric Garland of the Moores Cancer Center at UCSD calls breast cancer and colon cancer "Vitamin D deficient diseases." In many cases, making sure that your Vitamin D status is within the acceptable levels will help boost your immunity and could help protect you from diseases.

Research has also shown that people in the bottom quartile of Vitamin D status had a 26% increased rate of all-cause mortality. Higher Vitamin D levels have also been associated with higher levels of cognitive function and a lower risk of dementia in older adults as well as lower rates of respiratory tract infection. Studies have even shown a relationship between Vitamin D status and muscle mass and strength in adults as well as higher rates of obesity and metabolic syndrome in people with low levels.

This information is our best synthesis of the research and practical application at the time of this writing. Should new research come out contradicting our information and/or recommendation we will update as soon as possible. With our current knowledge, this information is accurate and recommendations are safe for the vast majority of the population.

Don't take our word for it: The Science Behind Vitamin D

Foss, Y.J. (2009). Vitamin D deficiency is the cause of common obesity. Medical Hypostheses, 72(3): 314-321.

Teegarden, D., Donkin, S.S. (2009). Vitamin D: emerging new roles in insulin sensitivity. Nutrition Research Reviews, 22(1): 82-92.

Garland, C.F., Garland, F.C., Gorham, E.D., Lipkin, M., Newmark, H., Mohr, S.B., Holick, M.F. (2006). The role of vitamin D in cancer prevention. American Journal of Public Health, 96(2): 252-261.

Melamed M.L., Michos, E.D., Post, W., Astor, B. (2008). 25-hydroxyvitamin D levels and the risk of mortality in the general population, Archives of Internal Medicine. 168 (15):1629-1637.

Balion, C., Griffith, L.E., Strifler, L., Henderson, M., Patterson, C., Heckman, G., Llewellyn, D.J., Raina, P. (2012). Vitamin D, cognition, and dementia: a systematic review and meta-analysis. Neurology, 79(13): 1397-1405.

American Orthopaedic Society for Sports Medicine. (2011). Vitamin D lower in NFL football players who suffered muscled injuries, study suggests. ScienceDaily,
Body Composition, Strength, and Athletic Performance

Grimaldi, A.S., Parker, B.A., Capizzi, J.A., Clarkson, P.M., Pescatello, L.S., White, M.C., Thompson, P.D. (2013). 25(OH) vitamin D is associated with greater muscle strength in healthy men and women. Medicine and Science in Sports and Exercise, 45(1):157-162.

Tomlinson, P.B., Joseph, C., Angioi, M. (2014). Effects of vitamin D supplementation on upper and lower body muscle strength levels in healthy individuals. A systematic review with meta-analysis. Journal of Science and Medicine in Sport, S1440-2440(14)00163-7.

Kremer, R., Campbell, P.P., Reinhardt, T., Gilsanz, V. (2009). Vitamin D status and its relationship to body fat, final height, and peak bone mass in young women. Journal of Clinical Endocrinology and Metabolism, 94(1):67-73.

Cannell, J.J., Hollis, B.W., Sorenson, M.B., Taft, T.N., Anderson, J.J. (2009). Athletic performance and vitamin D. Medicine & Science in Sports & Exercise, 41(5):1102-1110.

Hamilton, B. (2009). Vitamin D and human skeletal muscle. Scandinavian Journal of Medicine & Science in Sports, 20(2): 182-190.

Marantes, I., Achenbach, S.J., Atkinson, E.J., Khosla, S., Melton, L.J., Amin, S. (2011). Is vitamin D a determinant of muscle mass and strength? Journal of Bone and Mineral Research, 26(12): 2860-2871.
Demographic Risk Factors

Tseng, M., Giri, V., Bruner, D.W., Giovannucci, E. (2009). Prevalence and correlates of Vitamin D status in African American men. BMC Public Health, 9:191.

Ginde, A.A., Liu, M.C., Camargo, C.A. (2009). Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Archives of Internal Medicine, 169(6): 626-632.