The importance of calcium and vitamin D on bone health
Bone acts as a vast reservoir for minerals especially calcium. The body loses a certain amount of calcium in urine and faeces every day. These needs to be replaced by what we take through our diet. If the dietary intake is inadequate to replace the amount lost, then the difference is obtained from the skeleton and this leads to bone loss.
The absorption of calcium from the gut into the body is aided by Vitamin D. And therefore it is important that there is enough Vitamin D in our bloods to help with this process.
Calcium is obtained from dairy products. Vitamin D is synthesised in the skin from sunlight exposure. Individuals who are housebound or those that cover their skin are likely to be Vitamin D deficient. For these individuals a supplement from a tablet may be necessary for them to maintain their Vitamin D levels at an adequate level.
In the absence of gravity astronauts lose a lot of calcium from their bone and also a lot of bone density. Fortunately when they come back to the Earth and experience gravity this reverses. This tells us that it is important to do weight bearing exercises, as exercise helps maintains bone health.
Other life style risk factors that can affect bone health are smoking and consuming more than three units of alcohol per day (see also
Food, diet and supplements).
