Vitamin D - The Vitamin from the Sun

Vitamin D: The One from the Sun

Vitamin D is an interesting case. We need it as it part of our calcium regulation among a few other functions. But it is also one that our bodies can naturally produce. The trick though is getting enough sunlight. There are places where it is quite possible to do so regularly, but there are also areas where it is a bad idea to have exposed skin. The way this works is you supplement through your diet, the lack of sunlight.

Benefits
Stronger bones - Mix with a healthy amount of calcium and you won't have much to worry about
Immune System - This is handy in avoiding the flu. Vitamin D plays a role in your body's ability to defend itself
Defend against Cancer - Considering the vast influences of this one vitamin, it really is not too far fetched
Life Span - As noted, Vitamin D does a lot for the human body. Keep it well stocked and you should be fine

Getting Vitamin D
Vitamin D, apart from our own synthesis, can be found in a number of tasty dishes:
Fish (Catfish, Eel, Mackerel, Sardines, Salmon and Tuna)
Eggs
Beef Liver
Fish Liver Oils
Mushrooms (This is a only vegan source apparently)

Deficiency of Vitamin D
This is not so good. As mentioned previously, this can lead to a softening of the bones. The main one that people would have to worry about would be rickets. After that, Osteomalacia.

Recommended Dose
This will vary a good bit, as most of this is determined based on your level of sun exposure. While it is very possible to push things to a particular degree