A sufficient level of vitamin D makes the bones strong and teeth healthy; the cardiovascular system functions smoothly, the body is strong and muscles develop. It is safe to say that vitamin D is a foundation of a well-planned workout regimen.
Vitamin D deficiency
Insufficient levels of vitamin D initiate increased secretion of parathyroid hormone (PTH), responsible for calcium and phosphate balance regulation. This results in bone demineralization and in consequence creates a greater risk of osteoporosis.
Research shows that people suffering from vitamin D deficiency are more likely to develop cardiovascular disorders, diabetes, dementia and autoimmune diseases. It has also been linked to various types of cancer (mostly of colon, kidney, breast and prostate).
An opposite situation, in which there is an excess of vitamin D in the organism, occurs much more seldom, but is equally dangerous. Calcium deposition in tissues and internal organs, the most vulnerable being arteries and kidneys, may result in nephrolithiasis or calcinosis.
Vitamin D and its effect
on workout results
Vitamin D acts like a prohormone, i.e. a precursor of a hormone. It resembles a steroid in its chemical structure, for which reason it not only positively influences testosterone production but also increases the share of its biologically active form. As a consequence, intensive protein synthesis with faster muscle growth and regeneration can be observed.
Vitamin D also performs regulatory function of aromatase – an enzyme taking part in controlling the level of sex hormones. Vitamin D lowers its concentration in blood, which in turn increases the level of testosterone – a hormone crucial for developing strong and firm muscles.
Winter deficiency of vitamin D
Vitamin D originates during a process of synthesis in the skin induced by sun exposure. In winter, due to reduced amount of sunlight, people living in our climate zone are most likely to suffer from its deficiency. Tanning studios are not a solution to the problem, as the lamps do not emit UVB radiation, which is necessary to the forming of the vitamin.
The solution can be found in the diet. The main source of vitamin D is fish: mackerel, soused herring or smoked eel – freshwater fish considered to be lowest in fat – are all rich in vitamin D. Other sources of the vitamin are: cod-liver oil, liver, egg yolk, butter, cream, avocado and blueberries. It is also added to various convenience foods such as cereals or dairy products.
Sources of vitamin D
As mentioned previously, vitamin D forms during biochemical processes in the skin under the influence of sunlight: only 20 minutes in the sun covers 90% of your daily requirement.
According to health standards, the Recommended Dietary Allowance (RDA) for an adult is about 400 IU per day. The vitamin should come from fish (eel: 1200 IU/100g, herring in oil: 800 IU/100g, canned fish: 200 IU/100g) or other animal products (eggs: 50 IU/yolk, cheese: 10 – 30 IU/100g, cow’s milk: 0,4 – 1,2 IU/100g).
In some cases, however, a change in diet does not cover the requirement for vitamin D in full. In such situation supplementation is something worth considering. There are many types of supplements available on the market, so it is highly advised to consult a doctor to choose the best product for you and set an appropriate dosage.