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Coaches Plan - Expert Insight for Canada's Coaches



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March 2018 

Vitamin D and Sport Performance - More Than Just for Bones!

Written by Angela Dufour, MEd, RD, CSSD, IOC Dip Sports Nutr, CFE Performance Dietitian for the 2018 Winter Olympics

 Vitamin D, otherwise known as the sunshine vitamin, is a fat-soluble vitamin that is derived from cholesterol and stored in fat. Vitamin D is well known to help us absorb calcium from the gut to promote bone development and growth. But more recent research indicates it has so many more functions for maintaining health and optimizing training and performance in athletes. It is now thought that athletes who have adequate (or higher) intakes and levels of vitamin D might increase skeletal muscle function; (mass, strength and endurance), decrease recovery time from training, increase both force and power production and improve immune function, each of which could enhance athletic performance. (1, 2). Vitamin D in its active form also acts like a steroid hormone, interacting with over 1000 genes throughout the body, serving nerve signaling and blood pressure.

  • Vitamin D and Athletic Performance

    Bone Health

    Numerous studies have proven the positive influence of vitamin D on calcium and phosphate absorption in the gut and their impact on bone density and mineralization and remodeling (4, 5, 6).

    Skeletal Muscle Function and Recovery

    Vitamin D can indirectly affect the recovery and construction of muscle tissue by stimulating contraction and the nervous system, thus reducing reaction time and improving balance and coordination of movement, (7, 8, 9). Vitamin D may also play a role in increasing testosterone and steroid hormones, leading to an increase in skeletal muscle hypertrophy, strength and power output (10,11).

    Immune Function

    High training loads of athletes make them more susceptible to bacterial infections, (upper respiratory tract, cold, flu). Some studies have shown that by taking 2000 International Units (IU) daily of Vitamin D for one year can significantly decrease the incidence of common colds and flu (12, 13, 14, 15).

     

  • Are Athletes Getting Enough

    Simply put: NO! Vitamin D deficiency is on the rise throughout the world, surprisingly enough, 88.1 % of the world’ s population has inadequate vitamin D levels (16), particularly in the northern latitudes, where it can be hard to get enough sunshine, especially in the winter months. Reduced levels of vitamin D have been observed in athletes of various gender, age, and sport. Unlike other vitamins and minerals, only modest amounts of vitamin D come from food; (as seen in Table 1), instead, it is the sun’s ultraviolet B (UVB) rays that serve as our most efficient means of producing vitamin D. Therefore, athletes who train indoors or after sunset or who travel to foreign countries for training camps and competitions where dietary intakes of Vitamin D may be limited, may be at risk for Vitamin D deficiency. Severe, chronic vitamin D deficiency can lead to rickets, softened/weak-end and bowed bones that occur in children and adults, respectively.

    Other factors that influence how much active vitamin D athletes can obtain from the sun include:

    1. Time of year: vitamin D can only be synthesized when the sun is sufficiently high in the sky. For those living above 50° North, the sun’s zenith angle is low enough that vitamin D cannot be produced in the skin from October to early April.

    2. Time of day: even during the peak summer season in Canada, UVB is only sufficient to produce vitamin D in the skin through the middle of the day, 11:00am-2:00 pm. This means that athletes training outdoors in the evening or early morning will likely produce little vitamin D, even on exposed skin.

    3. Skin exposure: the most vitamin D is generated through UVB exposure on the torso, followed by the arms and legs, with the hands and face producing the least.

    4. Skin pigmentation: individuals with darker skin have higher levels of melanin, which acts as a natural sunblock, slowing the production of vitamin D in theskin.

    5. Altitude: UVB levels are higher at altitude than at sea level.

    6. Sunscreen: blocks 95-100% of vitamin D production.

    7. Cloud: complete cloud cover reduces UV levels by about half.

    8. Shade & severe pollution: reduce UV by about 60%.

    9. Glass: blocks UVB rays, so athletes who train indoors, even if they are exposed to daylight, will not produce vitamin D.

     

    TABLE 1: Vitamin D Content and Some Common Foods

    Vitamin D is not found naturally in many commonly consumed foods. In Canada, some foods such as milk, soy or rice beverages and margarine have vitamin D added to them. Good food sources of vitamin D include certain kinds of fish, egg yolks and milk. The following table will show you foods that are a source of vitamin D.

    Food

    Serving Size

    Vitamin D (IU)

    Vegetables and Fruit

    This food group contains very little of this nutrient

    Orange juice, fortified with vitamin D

    125 mL (½ cup)

    50

    Grain Products

    This food group contains very little of this nutrient.

    Milk and Alternatives

     

     

    Soy beverage, fortified with vitamin D

    250 mL (1 cup)

    86

    Milk (3.3 % homo, 2%, 1%, skim, chocolate milk)

    250 mL (1 cup)

    103-105

    Skim milk powdered

    24 g (will make 250 mL of milk)

    103

    Yogurt (plain, fruit bottom), fortified with vitamin D

    175 g (3/4 cup)

    58-71

    Meat and Alternatives

     

     

    Egg, yolk, cooked

    2 large

    57-88

    Pork, various cuts, cooked

    75 g (2 ½ oz)

    6-60

    Deli meat (pork, beef, salami, bologna)

    75 g (2 ½ oz)/ 3 slices

    30-54

    Beef liver, cooked

    75 g (2 ½ oz)

    36

    Fish and Seafood

     

     


    Salmon, sockeye/red, canned, cooked or raw

    75 g (2 ½ oz)

    394-636

    Salmon, humpback/pink, canned, cooked or raw

    75 g (2 ½ oz)

    392-447

    Salmon, coho, raw or cooked

    75 g (2 ½ oz)

    338-422

    Snapper, cooked

    75 g (2 ½ oz)

    392

    Salmon, chinook, raw or cooked

    75 g (2 ½ oz)

    383-387

    Whitefish, lake, cooked

    75 g (2 ½ oz)

    135

    Mackerel, Pacific, cooked

    75 g (2 ½ oz)

    343

    Salmon, Atlantic, raw or cooked

    75 g (2 ½ oz)

    206-245

    Salmon, chum/keta, raw or cooked

    75 g (2 ½ oz)

    203-221

    Mackerel, canned

    75 g (2 ½ oz)

    219

    Herring, Atlantic, pickled

    75 g (2 ½ oz)

    202

    Trout, cooked

    75 g (2 ½ oz)

    148-208

    Herring, Atlantic, cooked

    75 g (2 ½ oz)

    161

    Roe, raw

    30 g (1 oz)

    145

    Sardines, Pacific, canned

    75 g (2 ½ oz)

    144

    Halibut, cooked

    75 g (2 ½ oz)

    144

    Tuna, albacore, raw or cooked

    75 g (2 ½ oz)

    99-106

    Mackerel, Atlantic, cooked

    75 g (2 ½ oz)

    78

    Tuna, white, canned with water

    75 g (2 ½ oz)

    60

    Fats and Oils

     

     

    Cod liver oil

    5 mL (1 tsp)

    427

    Margarine

    5 mL (1 tsp)

    25-36

    Other

     

     

     

    Goat’s milk, fortified with Vitamin D

    250 mL (1 cup)

    100

    Rice, oat, almond beverage, fortified with Vitamin D

    250 mL (1 cup)

    85-90

     

    Source: "Canadian Nutrient File 2015"

    www.hc-sc.gc.ca/fn-an/nutrition/fiche-nutri-data/index-eng.php [Accessed From www.dietitians.caJanuary 2018].

  • How Much is Enough?

    The optimal dosage varies depending on the individual and the institution providing the guidelines in order to recap the above-mentioned performance benefits. Table 2 represents the recommendations of the Institute of Medicine (IOM), while the Endocrine Society (ES) recommends a slightly higher intake. Various organizations differ in what they determine is the lowest desirable serum level of Vitamin D in order to achieve full health benefits (17, 18, 19).

    How Much Vitamin D Should Athletes Aim For?

    Table 2: Recommended Dietary Allowances for Vitamin D (Institute of Medicine, 2010)*

    Age in Years

    Aim for an intake of international units (IU/day)*

    Stay below* IU/day

    Children <1 yr

    400

    1000-1500

    Children 1-8

    400

    2500-3000

    Children and Adults 9-70

    600

    4000

    Men and Women 51-70

    600

    4000

    Men and Women 71 and older

    800

    4000

    Pregnant and Breastfeeding Women 19 and older

    600

    4000


    *based on evidence to maintain blood levels of >50 nmol/L [11, 80, 81].
  • Are Vitamin D Supplements Needed for Athletes

    Vitamin D supplementation can be considered safe and appropriate for athletes who have low blood levels of vitamin D. Although exact levels are currently undetermined, it is suggested to be higher than general standards. In the absence of available screening and monitoring (e.g. blood work), a routine vitamin D supplement of 1000 IU of vitamin D per day may be considered safe and reasonable for all athletes. However, performance studies done on athletes were supplemented with 5000 IUs/day which is far greater than the recommended dosages of 600– 2000 IU/day. Thus, it remains unclear, but athletes may benefit from higher levels of Vitamin D than current recommended daily intakes in order to increase skeletal muscle function and reduce the risk of stress fractures. (2,20, 21, 22)

     

  • Vitamin D Types

    There are two major forms of Vitamin D; D3 (cholecalciferol) and D2 (ergocalciferol). Vitamin D2 is mainly used in the fortification of foods, and is absorbed lower than vitamin D3. Vitamin D3 is made in the skin and found naturally in foods.

    Commercial supplements can be in either form, however, Vitamin D3 may be the more effective.

     

  • Bottom Line

    Given the outlined numerous benefits of adequate Vitamin D to an athletes’ health, training and performance, it is important for athletes to get their Vitamin D status checked regularly during training. Parents and coaches can encourage more Vitamin D foods consumption to reap the sport performance benefits. However, in order to achieve optimal levels of Vitamin D, athletes who are at risk or who have below desirable levels (actual amounts are under review) (3, 18) may still need additional Vitamin D supplementation especially during winter months. More research is needed in athlete specific situations to determine optimal amounts of supplementation for its potential ergogenic benefits, but growing evidence has supported that 600– 800 IU/day may not be sufficient for optimal levels of vitamin D, in athletic population.

  • References

    1. Int Soc Sports Nutr. 2015; 12: 33. Published online 2015 Aug 19. doi: 10.1186/s12970-015-0093-8

    2. Dylan T. Dahlquist, Brad P. Dieter, and Michael S. Koehle. Plausible ergogenic effects of vitamin D on athletic performance and recovery,

    3. Bendik I, Friedel A, Roos FF, Weber P, Eggersdorfer M. Vitamin D: a critical and essential micronutrient for human health. Front Physiol. 2014;5:248.

    3. Holick M.F.: Vitamin D deficiency. N. Engl. J. Med., 2007; 357: 266-281

    4. Peckenpaugh N.J.: Mikrosk?adniki w zbilansowanych posi?kach: witaminy, minera?y i fitozwi?zki. In: Podstawy ?ywienia i dietoterapia, ed. Peckenpaugh N.J., Elsevier Urban & Partner, Wroc?aw, 2010, 93-95

    5. D’Antona G, Lanfranconi F, Pellegrino MA, Brocca L, Adami R, Rossi R, et al. Skeletal muscle hypertrophy and structure and function of skeletal muscle fibres in male body builders. J Physiol. 2006;570(Pt 3):611–27.

    6. Pfeifer M., Begerow B., Minne H.W., Schlotthauer T., Pospeschill M., Scholz M., Lazarescu A.D., Pollähne W.: Vitamin D status, trunk muscle strength, body sway, falls, and fractures among 237 postmenopausal women with osteoporosis. Exp. Clin. Endocrinol. Diabetes, 2001; 109: 87-92

    7. Stein M.S., Wark J.D., Scherer S.C., Walton S.L., Chick P., Di Carlantonio M., Zajac J.D., Flicker L.: Falls relate to vitamin D and parathyroid hormone in an Australian nursing home and hostel. J. Am. Geriatr. Soc., 1999; 47: 1195- 1201

    8. Close GL, Russell J, Cobley JN, Owens DJ, Wilson G, Fraser WD, et al. Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function. J Sports Sci. 2013;31:344–53.

    9. Herbst KL, Bhasin S. Testosterone action on skeletal muscle. Curr Opin Clin Nutr Metab Care. 2004;7:271–7.

    10. Urban RJ. Growth hormone and testosterone: Anabolic effects on muscle. Horm Res Pædiatrics. 2011;76:81–3.

    11. Close GL, Leckey J, Patterson M, Bradley W, Owens DJ, Fraser WD, et al. The effects of vitamin D(3) supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose–response study. Br J Sports Med. 2013;47:692–6.

    12. Welch TR, Bergstrom WH, Tsang RC. Vitamin D-deficient rickets: the reemergence of a once-conquered disease. J Pediatr. 2000;137:143–5.

    13. Simpson R, Thomas G, Arnold A. Identification of 1,25-dihydroxyvitamin D3 receptors and activities in muscle*. J Biol Chem. 1985;260:8882–891.

    14. Gregory SM, Parker BA, Capizzi JA, Grimaldi AS, Clarkson PM, Moeckel-Cole S, et al. Changes in vitamin D are not associated with changes in cardiorespiratory fitness. Clin Med Res. 2013;2:68.

    15. Bendik I, Friedel A, Roos FF, Weber P, Eggersdorfer M. Vitamin D: a critical and essential micronutrient for human health. Front Physiol. 2014;5:248.

    16. Endocrine S. Evalutation, treatment, and prevention of vitamin D deficiency: An endocrine society clinical practice guideline. 2011.

    17. Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am J Clin Nutr. 1999;69:842–56.

    18. Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B. Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. Am J Clin Nutr. 2006;84:18–28.

    19. Vieth R. Why the optimal requirement for Vitamin D3 is probably much higher than what is officially recommended for adults. J Steroid Biochem Mol Biol. 2004;89–90:575–9.

    20. Cannell J, Hollis B. Use of vitamin D in clinical practice. Altern Med Rev. 2008;13:6–20.

    21. Heaney RP. Assessing vitamin D status. Curr Opin Clin Nutr Metab Care. 2011;14:440–44.

    22. Stacgowicz, M Lebiedzinska, A. The role of vitamin D in health preservation and exertional capacity of athletes, Postepy Hig Med Dosw (online), 2016; tom 70: 637-643

 

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