Vitamin D and Athletic Performance - Are you getting enough?
Why you should be supplementing with Vitamin D!
Vitamin D is another of the few ‘supplements’ we recommend as it plays a vital role in maintaining a strong and healthy immune system. With most other supplements, we suggest you get them not through supplementation but through a well-balanced, healthy diet (protein for example). However, that can be difficult with Vitamin D, especially during the winter months when sunshine is limited. You see, the primary source of Vitamin D is synthesis in the skin when exposed to sunlight. It can also be got through the diet in foods such as eggs, salmon, mackerel, tuna and sardines, and these become our main source of Vitamin D in the sunshine-depleted winter months. If you are not taking in these foods, and have limited exposure to sunshine year round, then you should be supplementing with Vitamin D during these months – or for 8 months of the year if you live in Ireland!
So what exactly is Vitamin D and why is it so important? Vitamin D is a fat-soluble vitamin which acts as a lipophilic pro-hormone. It serves many functions in the body – it induces calcium mobilisation for bone turnover, allows for calcium absorption within the gut, maintains blood calcium and phosphorous balance, as well as enhancing muscle function and contributing to the development of healthy bones and joints. The importance of Vitamin D to our overall health is clear to see. Furthermore, a deficiency in Vitamin D has been linked to high blood pressure, cardiovascular disease, osteoarthritis, lower immune function and even certain cancers. It also plays a role in mental health as deficiency has been linked to symptoms of depression and seasonal affective disorder (SAD) which occurs in the winter months, coinciding with the time of year Vitamin D is least available through natural sunlight. Deficiency is even more prominent in elderly populations. A number of reasons can account for this, including a decreased dietary intake, decreased exposure to sunshine, decreased skin thickness and impaired intestinal absorption. With these in mind, supplementing with Vitamin D becomes very important (and we strongly advise it) for elderly people. In fact, studies have shown that doing so can reduce the likelihood of falls and fractures in the elderly, because bone health (enhanced calcium absorption) and muscle function are both improved. We also encourage the elderly to increase their intake of Vitamin-D rich foods, in addition to supplementation.
Do athletes need Vitamin D?
In addition to the aforementioned roles of vitamin D, research has shown that vitamin D plays an active role in protein synthesis, muscle function and immune and inflammatory responses. With 77% of our population considered to be Vitamin D deficient, it is probable that the deficiency is high in our athletes! This has begun to be examined by many sports physicians and scientists. The molecule on the cell which receives vitamin D and allows its uptake is known as the Vitamin D Receptor (VDR). These VDRs have been identified in the skeletal muscle indicating it as a target organ for Vitamin D use. As mentioned earlier, Vitamin D has a role in calcium transportation. This is a proposed mechanism for its role in enhancing sports performance, as calcium is involved in muscle contraction. Additionally, it has been shown that supplementation with Vitamin D in individuals with a low status can increase muscle strength. This is thought to be due to increases in type II muscle fiber (fast twitch) size and amount. These type II fibers are the muscle type predominantly involved in speed and power activities. These findings indicate Vitamin D may have a truly significant role in muscle performance, injury prevention, and consequently athletic performance. More research is necessary in this area however, to uncover the true role and cellular mechanisms by which Vitamin D impacts muscle performance.
How much should I take?
In terms of how much Vitamin D to take, the literature suggests 1000 – 2000 IU daily, throughout the winter months. This is quite high as the RDA for Vitamin D is 800 IU, which is probably closer to the amount you should be aiming for! So where can you get ~800 IU each day? Well, in periods of sunshine (our one week of summer in Ireland!), 15-20 minutes of unprotected exposure to sunshine (before 3pm) can produce as much as 20,000 IU of Vitamin D, more than a sufficient amount! However, when the sun is not shining and exposure is limited, we must attempt to obtain a sufficient amount through our diet. Foods such as salmon are rich in Vitamin D (3oz of salmon provides roughly 794 IU), but other sources are much lower (egg yolk provides 40 IU for example) which leads to the need for supplementation. Supplement with the appropriate amount – it is not a case of the more the merrier, as excessive amounts can actually have negative effects on your health. Finally, if you think you are deficient in Vitamin D or you have an elderly relative who you think may be deficient, you should get their bloods checked by a doctor, as deficient people may need much stronger doses!