VITAMIN D DEFICIENCIES IN THE WINTER TIME CAN SLOW YOU DOWN ATHLETICALLY AND GET YOU SICK! HERE ARE TWO REVIEWS CONSIDER TO STUDY PRACTICE, AND TEACH OTHERS.
Until recently, the relationship between vitamin D and athletic performance received minimal attention. Some colleagues began to evaluate this relationship in 2009, they wrote the first paper about vitamin D and athletes in 50 years.
Cannell JJ, Hollis BW, Sorenson MB, Taft TN, Anderson JJ. Athletic performance and vitamin D. Med Sci Sports Exerc. 2009 May;41(5):1102-10. doi: 10.1249/MSS.0b013e3181930c2b. Review.
In 2010, a book was written called: Athlete’s Edge, faster, quicker, stronger with vitamin D.
Since our 2009 paper alerting team physicians and athletic trainers to the importance of vitamin D in athletic performance, there have been 24 studies examining the prevalence of vitamin D insufficiency [25(OH)D < 32 ng/ml] in athletes. It turns out that 56% of the 2,313 athletes studied were vitamin D insufficient. Farrokhyar F, Tabasinejad R, Dao D, Peterson D, Ayeni OR, Hadioonzadeh R, Bhandari M. Prevalence of vitamin D inadequacy in athletes: a systematic-review and meta-analysis. Sports Med. 2015 Mar;45(3):365-78. doi: 10.1007/s40279-014-0267-6. Review. Now a Canadian group has reviewed selected papers on the recent evidence that supports vitamin D has an effect on athletic performance. Dahlquist DT, Dieter BP, Koehle MS. Plausible ergogenic effects of vitamin D on athletic performance and recovery. J Int Soc Sports Nutr. 2015 Aug 19;12:33. doi: 10.1186/s12970-015-0093-8. eCollection 2015. Review. They reviewed five areas in some depth. 1) Oxygen consumption Cross-sectional studies on oxygen consumption are mixed. However, Jastrzebski et al performed a single-blinded trial of supplementation with 6000 IU/day of vitamin D3 versus a placebo during an 8-week training cycle in 14 elite lightweight rowers with sufficient 25(OH)D concentrations (>30 ng/mL).
The research team wanted to determine the effects of vitamin D supplementation on VO2 max. VO2 max is a measurement used to determine the maximum amount of oxygen an athlete can utilize. They demonstrated a significant increase in VO2 max of 12.1 % and 10.3 % in the vitamin D group and placebo group, respectively.
2) Muscle inflammation
In a randomized, double-blind, placebo-controlled study, Barker et al. reported that 4000 IU/day for 35 days attenuated the inflammatory biomarkers alanine (ALT) and aspartate (AST) immediately following 10 sets of 10 repetitions of peak isometric force eccentric-concentric jumps. Furthermore, although peak power output decreased throughout the sets and repetitions in both of the groups, the supplementation group only decreased by 6%, while the placebo group’s power decreased by a significant 32%. This significant discrepancy persisted at 48 hours.
3) Force and Power production
Cross-sectional studies of force and power are certainly mixed. Close et al. conducted an 8 week randomized controlled trial in 30 athletes using 5000 IU/day of vitamin D or a placebo; the vitamin D group had a significant increase in 10-m sprint times (P = 0.008) and vertical jump (P = 0.008) when compared to the placebo group. When Close et al. attempted a RCT using weekly doses of vitamin D, they found no effect on performance, showing – perhaps – vitamin D must be given daily.
4) Testosterone production
Testosterone is known to affect athletic performance; that’s why it’s banned. Pilz et al. conducted a 12-month, double-blind, randomized control trial in 54 non-diabetic obese males and demonstrated that the group receiving 3300 IU/day of vitamin D had a significant 30% increase in circulating total testosterone (P=0.001), bioactive testosterone (P=0.001) and free testosterone levels (P=0.001).
5) Vitamin K
For the first time, the authors raised the question, “is vitamin K important for athletic performance?” To the best of my knowledge, no studies exist on the subject.
The authors concluded:
“Based on the research presented on recovery, force and power production, 4000-5000 IU/day of vitamin D3 in conjunction with a mixture of 50 mcg/day to 1000 mcg/day of vitamin K1 and K2 seems to be a safe dose and has the potential to aid athletic performance.”
“Lastly, no study in the athletic population has increased serum 25(OH)D levels past 40 ng/ml (100 nmol/L), (the optimal range for skeletal muscle function) using doses of 1000 to 5000 IU/day. Thus, future studies should test the physiological effects of higher dosages (5000 IU to 10,000 IU/day or more) of vitamin D3 in combination with varying dosages of vitamin K1 and vitamin K2 in the athletic population to determine optimal dosages needed to maximize performance.”
I advise team physicians and athletic trainers to make sure their athletes have, at least, “natural” blood levels of vitamin D. Free-living hunter-gatherers in modern day equatorial Tanzania have mean levels of 46 ng/ml. Nature may know what it is doing.
As far as vitamin K is concerned, we agree that it is a “co-factor” of vitamin D. That’s why they advised Bio Tech to put vitamin K in the only vitamin D formula the Vitamin D Council endorses, D3Plus, which, by the way, contains 800 mcg of vitamin K as well as the co-factors, magnesium, zinc and boron.