Vitamin D is the nutrient of the moment and for GOOD reason! I remember attending a Caroline Walker trust nutrition conference as a newly qualified Dietitian back in 2011 where a leading professor in micronutrient metabolism was explaining how sun cream could be causing more harm than good by reducing our absorption of the all important vitamin D. In fact, the same professor was asserting that vitamin D is THE most overlooked nutrient in terms of health, well-being, longevity and PERFORMANCE, and we as health and nutrition professionals should be raising its profile.
Vitamin D and performance were not usually strung together in the same sentence because of emphasis surrounding its key role in absorption of calcium and supporting bone mineral density. However, improvements in bone mineral density has a direct association with performance, so it made absolute sense that researchers and sporting professionals were beginning to link this vitamin to performance more and more often.
Vitamin D is now understood to improve bone mineral density, reduce the risk of osteoporosis/arthritis and ostemalacia (softening of the bones), as well as potentially offsetting the risk of type 1 diabetes, alleviating muscle and joint pain and reducing risk of cancers of the breast, colon, ovaries and more.
So I think you’ll agree that vitamin D may in one form or another effect performance! This being said, some compelling and well conducted evidence from Agergaard, J. et al. (2015) uncovered some even more interesting performance related findings on vitamin D and performance…this time MUSCLE RELATED!
A 16 week study compared two groups, one that consumed 48 micrograms of vitamin D + 800mg calcium, and the other consuming just 800mg calcium (placebo-group). Subjects were restricted to low sunlight levels to offset natural vitamin D effecting results, and the results were significant.
The group that consumed the 48 micrograms of vitamin D didn’t appear to improve muscle size and strength directly. HOWEVER, there were improvements in the muscle quality and fibre type which indicates vitamin D can improve skeletal muscle remodelling, a process that promotes adaptive changes in muscle structure. Basically, our muscles have a characteristic known as phenotypic plasticity which means muscle structure is directly linked to the patterns of movement and use we put it through. In other words, vitamin D may well improve your muscles ability to adapt to the resistance training, sporting performance or whatever it may be that you do, in turn improving muscle longevity and performance.
Jakob Agergaard., Jeanette Trøstrup., Jacob Uth., Jonas Vestergard Iversen., Anders Boesen., Jesper L. Andersen., Peter Schjerling and Henning Langberg. (2015). Does vitamin-D intake during resistance training improve the skeletal muscle hypertrophic and strength response in young and elderly men? – a randomized controlled trial. Nutrition & Metabolism. 12:32. DOI: 10.1186/s12986-015-0029-y