Vitamin D is also called cholecalciferol. It is a fat soluble vitamin that is found in some foods but it is unusual in that it can also be manufactured by your body after exposure to sunlight.
What is Vitamin D used for?
Vitamin D is mainly used by the body to maintain the levels of Calcium and Phosphorus. These 2 minerals are vitally important for strong bones and teeth. A lack of Vitamin D results in a medical condition called Rickets in children, where the bones become thin, brittle and are often malformed. Lack of Vitamin D in adults results in a condition called osetomalacia where you will experience muscular weakness on top of having weak bones.
Where is Vitamin D found?
You can get Vitamin D from the food you eat - because Vitamin D is necessary for the absorption of Calcium, the milk you drink is often fortified with Vitamin D to increase the amount of Calcium you would absorb through your gut. The main natural sources of Vitamin D include fatty fish (eg salmon, sardines) and liver.
As mentioned above, you can also get Vitamin D from exposure to sunlight which the skin will convert to Vitamin D. It is important to note that whilst sun exposure is helpful in this respect, you need to take care with overexposure which would lead to sun burn and subsequent skin cancers.
In wintertime when we are all rugged up, the amount of sun exposure to our skin would be insufficient to produce adequate Vitamin D. Therefore, with individuals that have limited sun exposure, it is vitally important for them to get good sources of Vitamin D through their diet.
Factors which increase our chances of being deficient in Vitamin D
- Older folk tend to have an increased chance of being Vitamin D deficient. The ability of the skin to convert sunlight to Vitamin D diminishes as you age. Therefore some older folk will need Vitamin D supplementation.
- People with limited sun exposure for one reason or another eg those that are homebound, those living in cold regions like Alaska, people who cover up all areas of their skin for religious reasons, people working shift work (sleep in the daytime and work at night). These people may need Vitamin D supplementation.
- People who can't absorb fat in their diets well eg in Crohn's disease, cystic fibrosis.
Other people who may need supplemental Vitamin D include post menopausal women - who are often at risk of osteoporosis and hip fractures as a result of a Vitamin D deficiency.
Can I have too much Vitamin D?
Vitamin D is toxic in high doses - this is unlikely unless you consume excessive quantities of cod liver oil, or take it via supplements. Too much Vitamin D results in symptoms including nausea, vomiting, constipation, weakness, heart rhythm abnormalities and calcium deposits in the kidneys.