D-Stress From Fracture Risk
Sun & Supplements: What Research is Teaching Us About Athletic Demands
Sun & Supplements: What Research is Teaching Us About Athletic Demands
Like the tighty-whitey underpants that Tom Cruise wore in Risky Business, I’ll try to be brief, as there is a lot to unpack here. (ooh, did I go too far? Do tell in the comments)
It is generally accepted in most parts of the US that people will test low on vitamin D. A recent study suggests that 1 billion people worldwide have low vitamin D levels (Holick, MF). Vitamin D is essential for calcium maintenance, bone health along with having a role in hypertension, diabetes, cancer, autoimmune, and infectious diseases, along with other important functions (Palacios). Our focus here will be on bone health and muscles.
Normally, we would expect to create adequate vitamin D from sun exposure, however, this may not always be feasible in the winter months and sunscreen and avoiding the heat of the day in warmer months may preclude many of us from getting enough intake when outside. Some have advocated for getting some sun exposure in the first 15 minutes of being outside in the warm seasons with a significant amount of skin exposed and applying sunscreen thereafter to protect from excessive UV radiation. Darker-skinned people require a little more time in the sun to generate Vitamin D, and discussions have ensued as to whether it is often feasible in certain latitudes year-round, thereby necessitating the need for supplementation. A concerning statistic regarding sun exposure is the following finding from the National Collegiate Athletic Association, stating that the “ prevalence of vitamin D deficiency and insufficiency was 33.6.%, despite taking place in southern California during the summoner months.” (Vaillacis D)
Kids spending time doing aggressive indoor sports with less sun exposure, may have a special susceptibility to stress fractures. A recent study entitled, “Vitamin D and Stress Fractures in Sport: Preventive and Therapeutic Measures - A Narrative Review”, has good insight into this topic.
Of interesting note in this study are the risk factors for stress fractures (this study looked mostly at the lower extremities):
Female,
Age, with athletes over 40 and under 18 most at risk.
Anatomic factors can include High or low foot arches, knock-knees, leg length discrepancies. Essentially, any biomechanical disparity would lend to repeated uneven or excessive loading on bone.
Low bone density, is a risk factor.
Though the study identified low fitness levels as a precursor, there is also increased risk with dramatic changes of increase in activities.
The low end of normal vitamin D levels in the blood is close to 30-32 ng/ml according to most guidelines, and here is where the discussion should really begin. The study suggests that data is showing benefits at higher vitamin D levels but the consensus meetings have not yet taken place or don’t agree, etc. To this point, the researchers cited a few studies showing that the risk of stress fractures are less when the blood Vitamin D levels were above 40 ng/ml, and amounts just above 50 ng/ml may be optimal in so far as muscular benefits, as lower levels were mentioned to affect muscular output. This was measured as reduced muscle strength, mobility, and a reduction in the ability to jump and sprint (when testing young football players). To this higher level of maximal performance, the researchers echoed a study stating that “A target prevention of stress fractures would be a serum 25(OH) vitamin D of 40ng/ml or greater, achievable with 4000 IU/day of supplementation.”
Overall, it’s as though current recommendations pertain mostly to the general population, and that things may be different with a separate athletic council on injury prevention. In other words, why make universal recommendations because of a highly active subset of the population and burden those that are content with playing Fortnite on the couch? Perhaps because when obese or even just sedentary people decide to exert and load their skeletons to a high degree, they carry a higher level of susceptibility to stress fractures due to ill-adapted bone density to meet such demands. Maybe at some point reference ranges for athletes along with other subsets of the population will be listed on blood panel results? Until then, this is why we do and should always discuss our lab findings with our doctors.
I’ll reiterate the descent in performance and bone integrity here: The researchers quote studies suggesting that about “50 ng/ml are required for maximal athletic performance, below 40n/ml are highly associated with increased prevalence of stress fractures and lower than 30ng/ml are associated with increased risk of stress fractures, bone mineralization issues, and reversible muscular conditions.” It makes me wonder if CAM or Pincer boney changes that reshape portions of the hip and socket and are more likely to occur in athletes due to an increase in demands on the skeleton - along with their higher bone mineralization requirements not being met? With regards to reference ranges, this survey of the literature is just a narrow focus looking at bone and muscle performance and doesn’t cover the vitamin D ranges to better aid insulin or blood pressure regulation in certain populations requiring higher amounts within the normal reference ranges. This is why the Endocrine Society may have different interpretations than some of the other councils, but regardless of conditions, the NIH states that “optimal serum concentrations have not been established because they are likely to vary by stage of life, by race, and ethnicity.”
Just to give insight as to why it’s good to determine your desired levels with your doctor while using such research as a guide, here are several distinct recommendations for Vitamin D intake:
Current literature review study focusing on bone/muscular health: 800 IU/day with a foreseeable increase to 2,000 IU/ day.
US RDA: 600 IU/day
Endocrine Society: Adults might need 1,500-2,000 IU/day, and children and adolescents might need 1,000 IU/day
The UK council (apparently located near the Ministry of Magic) says 400 IU/day for everyone over age 4, which is confirmation of why we declared independence. (We threw tea into the harbor because if we threw Milk fortified with Vitamin D, it would not have phased them one bit as the heaving of their precious low nutrient-dense teas)
For Obesity, the Endocrine Society guidelines recommend that adults with obesity need two to three times more vitamin D (6000–10,000 IU/day) to treat and prevent vitamin D deficiency.
As we are waiting for guidelines to agree and create specialized ranges, along with intake amounts for subsets of the population with regards to skin color, body weight, athleticism, age, geographic latitude, etc. , let the daily intake requirements from review studies such as the ones referenced here, and blood work interpreted with your primary care provider guide you, and may the ng/ml ratio ever be in your favor.
-Dr. Goodbender
References
Holick MF, Chen TC . Vitamin D Deficiency: a worldwide problem with health consequences. Am J clin Nutr. 2008 Apr;87(4):1080S-6S.
Palacios, Cristina and Gonzalez, Lilliana. Is Vitamin D deficiency a major global public health problem? J Steroid Biochem Mol Biol. 2014 Oct; 144PA;138-145.
Villacis D, Yi A, Jahn R, et al. Prevalence of abnormal vitamin D levels among division I NCAA athletes. Sports Health. 2014;6:340-347.
Knechtle, Beat, Jastrzebski, Zbigniew. Vitamin D and Stress Fractures in Sport: Preventive and Therapeutic Measures - A Narrative Review. Medicina (Kaunas). 2021 Mar; 57(3);223.
Dr. Goodbender authored:
Lord O’sis: An Ounce of Back Pain Prevention for Our Pint-Sized Peeps, available on Amazon
A graphic novel for kids and parents with a “search and find” and tips for reinforcing good posture and body mechanics
Facebook Parenting Group: Slumping-Spine Fighters!
(© Dr. Goodbender, Ergocomical, PA and is available only by written permission. ) Please reach out to us via e-mail for Public Speaking & Consulting
© Dr. Goodbender, lives with his two dogs, 2-Crap and Shitcore, just off the coast of Newfoundland, which is already off the coast of Canada thereby putting him back on the mainland. Good Shabbos.
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