Grab a glass of milk and roll your sleeves up! You’ve probably heard that calcium is good for building strong bones and that vitamin D is the ‘sunshine vitamin’. But what are they and why are they important?
Our TeamYSN guest writer, Liam Oliver, Performance Nutritionist at British Diving, offers practical solutions and explanations in this short article.
Calcium
A mineral found in dairy (milk, cheese etc), fish, vegetables (such as broccoli) and fortified foods; calcium is crucial for bone growth and healthy teeth. It is involved in muscle actions that we use in everyday activities, competition, and training.
Generally, 2-3 servings of dairy per day are recommended. Unless, of course, you are lactose intolerant or have another restricting condition.
Poor dietary calcium intake, combined with protein-energy malnutrition, is associated with slow growth in height and weight, plus bone growth and maturation (1).
Adolescents require more calcium (see below). It is vital for a healthy bone mineral density (BMD). Low BMD is associated with a high risk of rickets in children (soft, weakened bones), and osteoporosis in later life – a degenerative condition (2).
The recommended intakes for different ages and populations in the UK are found below, plus a guide on serving sizes and amounts in different dietary sources.
Note: These recommendations consider the amount needed to maintain calcium balance and encourage bone accretion (growth), with approximately 26% of bone mineral increasing during puberty (3).
Exercise and weight-bearing activity (even high-impact such as jumping) are beneficial for such growth. Low calcium intakes and lower activity levels have shown an association with the occurrence of fractures (4). The importance of calcium, particularly in young, growing athletes, is clear.
Serving sizes and measure guides of different dietary calcium sources (Liam Oliver, @liam_oliver12, b5007971@my.shu.ac.uk)
Reference Nutrient Intakes for calcium in the UK for different populations (13).
Vitamin D
Eggs, oily fish, and red meat are good sources of Vitamin D. In its active form, after full metabolism in our bodies, Vitamin D plays an important role in the regulation of calcium and phosphate (5).
How much we produce is influenced by our age, season, skin pigmentation and even where we live and train.
These are significant considerations for athletes given that you may be training indoors, in a winter sport, or you generally don’t have much sunlight exposure.
Those with darker skin have higher levels of melanin, which acts almost like a constant sunscreen for the skin (6), and may need much more ultraviolet radiation exposure (i.e. sunlight) to produce the same amount of vitamin D as a fair-skinned individual (7).
Vitamin D intake has been shown to be associated with increased neuromuscular (8) and muscle performance (9). A more recent study showed that serum (in the blood) vitamin D levels were directly related to muscle force, power, velocity and jump height in adolescent girls (10).
In the summer, we can get plenty of vitamin D from sunlight. In autumn and winter, dietary intake of vitamin D becomes more important. Sufficient vitamin D intake can be difficult to achieve purely through our diets.
Thus, a combination of dietary sources and supplements may be considered. Remember to check that supplements are batch-tested! Recommend intakes and examples of dietary sources are shown below.
Vitamin D content of different foods. Adapted from Finglas et al. (2015) (11).
Vitamin D recommendations for different age groups (British Nutrition Foundation, 2016) (12)
Take-Home Message
In conclusion, calcium and vitamin D are vital for health and performance – particularly for younger athletes. Adequate overall energy intake, micronutrients, vitamins, and minerals (with higher calcium requirements in mind) will help you to reach your full potential for growth and maturation.
Unless you have a condition preventing you from doing so, you may be able to achieve adequate intake through diet alone. Supplements may be considered, in consultation with a qualified nutritionist or health professional.
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Our rockstar Vitamin D3 is sourced from cholecalciferol (pronounced: KOE-le-kal-SIF-er-ol), the most biologically active form of vitamin D found in humans and animals. And, our Calcium is combined with Phosphorus and Magnesium which work together to help maintain & construct healthy bones
About the Author: Liam Oliver, BSc (Hons) Sport and Exercise Science
University and Performance Nutritionist at British Diving.
Liam is aiming to complete a Masters course in Sports Nutrition and become SENr-accredited.
Twitter - @liam_oliver12
ResearchGate - Liam Oliver
Reference List
1. Theobald, H. E. (2005). Dietary calcium and health. British Nutrition Foundation. Nutrition Bulletin, (30), 237–277.
2. http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Calcium.aspx
3. Flavia Meyer, Helen O'Connor & Susan M. Shirreffs (2007) Nutrition for the young athlete, Journal of Sports Sciences, 25:S1, S73-S82, DOI: 10.1080/02640410701607338
4. Pires, L. A., Souza, A. C., Laitano, O., & Meyer, F. (2005). Bone mineral density, milk intake and physical activity in boys who suffered forearm fractures. Jornal de Pediatria, 81, 332 – 336.
5. Michael E. Angeline, MD, Albert O. Gee, MD, Michael Shindle, MD, Russell F. Warren, MD, Scott A. Rodeo, MD (2013). The Effects of Vitamin D Deficiency in Athletes. The American Journal of Sports Medicine (41), Issue 2, 461 – 464. 10.1177/0363546513475787
6. Cannell JJ, Hollis BW, Sorenson MB, Taft TN, Anderson JJ (2009). Athletic performance and vitamin D. Med Sci Sports Exerc., 41 (5), 1102-1110.
7. Cannell JJ, Hollis BW, Zasloff M, Heaney RP. Diagnosis and treatment of vitamin D deficiency. Expert Opin Pharmacother. 2008;9:107-18
8. Bischoff-Ferrari HA, Dietrich T, Orav EJ, et al. (2004). Higher 25-hydroxyvitamin D concentrations are associated with better lower-extremity function in both active and inactive persons aged > or =60 y. Am J Clin Nutr. 80 (3), 752-8
9.Young A, Edwards R, Jones D, Brenton D. Quadriceps muscle strength and fibre size during treatment of osteomalacia (1981). Stokes IAF, editor. Mechanical Factors and the Skeleton. Vol. 12. London (England): John Libbey, 137-45
10. Ward KA, Das G, Berry JL, et al. (2009). Vitamin D status and muscle function in post-menarchal adolescent girls. J Clin Endocrinol Metab., 94 (2), 559-563.
11. Finglas PM, Roe MA, Pinchen HM, Berry R, Church SM, Dodhia SK, Farron-Wilson M & Swan G (2015). McCance and Widdowson’s The Composition of Foods, Seventh summary edition, Cambridge: Royal Society of Chemistry.
12. Revised Nutrition Guidelines (October 2016). British Nutrition Foundation.
13. https://www.bda.uk.com/foodfacts/Calcium.pdf
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