Vitamin D and Athletic Performance: New Links Found

Vitamin D and Athletic Performance: New Links Found

Vitamin D is one of the most discussed supplements among athletes — and for good reason. Research over the past decade has revealed a surprisingly strong connection between vitamin D status and athletic performance. Even more concerning, approximately 56% of athletes have insufficient vitamin D levels (Farrokhyar et al., 2015).

Athletes and Vitamin D Deficiency

The systematic review published by Farrokhyar et al. (2015) analyzed multiple studies on athletes' vitamin D status. The results are striking:

• ~56% of athletes have insufficient vitamin D levels
• Indoor athletes are at higher risk
• Seasonal impact is significant — deficiency is more prevalent in winter months
• Even athletes in sunny countries experience deficiency (excessive sun protection, indoor training)

It is paradoxical: athletes, who care about their bodies the most, often suffer from a vitamin deficiency that would be easy to prevent.

Vitamin D Receptors in Muscle Tissue

Owens et al. (2017) demonstrated that vitamin D receptors (VDR) are present in muscle tissue. This is a significant discovery because it provides a biological explanation for why vitamin D affects muscle function.

Vitamin D receptors in muscle tissue mean that:

• Vitamin D directly influences muscle protein synthesis
• It particularly affects Type II muscle fibers (fast-twitch fibers), which are critical for strength and speed
• Deficiency can directly impair muscle function, not just indirectly

EFSA has confirmed that vitamin D contributes to the maintenance of normal muscle function — and we now understand the mechanism behind this much better.

Performance Improvement When Correcting Deficiency

Close et al., 2013: Sprints and Jump

Close et al. (2013) studied athletes with vitamin D deficiency and provided them with vitamin D supplementation. Results:

• Sprint times improved after vitamin D levels normalized
• Vertical jump height increased
• Changes appeared within just a few weeks of correcting deficiency

An important nuance: improvements were observed in athletes who were previously deficient. Those who already had sufficient levels did not see significant additional benefits from supplementation.

Mechanisms Behind Performance

Scientists have identified several ways vitamin D affects athletic performance:

Vitamin D and Protein Synthesis

An interesting connection exists between vitamin D and protein. Vitamin D influences muscle protein synthesis at multiple levels:

• Regulates gene expression related to muscle growth
• Influences the mTOR signaling pathway — one of the main mechanisms regulating muscle growth
• Supports amino acid uptake in muscle tissue

This means that even optimal protein intake may not yield maximum results if vitamin D levels are low. For athletes, vitamin D status is therefore doubly important.

An Athlete's Vitamin D Strategy

Testing

• Test at least once a year, ideally at the end of winter (February–March)
• Target level for athletes: 75–125 nmol/L (some sports nutrition scientists recommend even higher)
• Especially important if you train primarily indoors

Dosing for Athletes

• Correcting deficiency: under medical guidance, often higher doses short-term
• Maintenance dose: 1,000–2,000 IU (25–50 µg) daily, depending on individual factors
• Seasonal adjustment: higher dose in winter, summer depends on sun exposure

Practical Tips

1. Take vitamin D with fat-containing food — e.g., after training with your recovery meal
2. Combine with protein — protein powder with vitamin D may support optimal muscle recovery
3. Don't forget vitamin K2 — supports directing calcium to bones
4. Be consistent — daily dosing is better than infrequent large doses

Special Needs of Estonian Athletes

Estonia's location at the 59th parallel means local athletes are particularly vulnerable to vitamin D deficiency:

• From October to March, UV-B radiation is insufficient for vitamin D synthesis
• Many training sessions happen indoors (gyms, pools, indoor tracks)
• Even in summer, intensive training can mean long hours indoors

MaxFit.ee offers vitamin D products suitable for athletes that meet European quality standards.

Conclusion

• ~56% of athletes have insufficient vitamin D levels (Farrokhyar et al., 2015)
• Vitamin D receptors are present in muscle tissue, affecting Type II fibers (Owens et al., 2017)
• Correcting deficiency improved sprint times and vertical jump (Close et al., 2013)
• Vitamin D influences muscle protein synthesis and recovery
• Target level for athletes: 75–125 nmol/L
• Daily dosing of 1,000–2,000 IU is recommended
• Estonian athletes are geographically especially vulnerable

EFSA confirms: vitamin D contributes to the maintenance of normal muscle function.

References

• Farrokhyar, F., Tabasinejad, R., Dao, D., et al. (2015). Prevalence of vitamin D inadequacy in athletes: a systematic review and meta-analysis. Sports Medicine, 45(3), 365--378.
• Owens, D. J., Sharples, A. P., Polydorou, I., et al. (2015). A systems-based investigation into vitamin D and skeletal muscle repair, regeneration, and hypertrophy. American Journal of Physiology -- Endocrinology and Metabolism, 309(12), E1019--E1031.
• Close, G. L., Russell, J., Cobley, J. N., et al. (2013). Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK. Journal of Sports Sciences, 31(4), 344--353.
• Owens, D. J., Allison, R., & Close, G. L. (2018). Vitamin D and the athlete: current perspectives and new challenges. Sports Medicine, 48(Suppl 1), 3--16.

Dietary supplements are not a substitute for a varied, balanced diet and healthy lifestyle.

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