We often speak about vitamins, now perhaps, the most studied, is the Vitamin D that is affecting the scientific community, not only for its ability to increase the absorption of calcium, but also for its effect on the immune system, also in HIV.
Vitamin D has effect on the prevention of heart disease, hypertension, asthma in cognitive disorders, depression, multiple sclerosis, diabetes metabolic syndrome, in cancer, psoriasis, alopecia areata, vitiligo and in atopic dermatitis.
Vitamin D is a steroid hormone that contributes to many biological reactions.
The main effect of this vitamin is to allow the absorption of calcium and phosphorus, essential for our bones.
Its main source is the sun, vitamin D is the only vitamin synthesized by the body and it’s no a coincidence that humans have skin color lighter or darker according to the latitude in which they live, this means that in the states where we have fews sunny days , the skin of individuals is clearer to allow greater absorption of UV rays for the synthesis of vitamin D, which can also be regulated by genetic laws.
The lack of vitamin D is due to a lack of regular exposure to sunlight, by the work indoors, and the excessive use of sun protection creams.
This is certainly not the reason to expose yourself to the sun indiscriminately or to make tanning beds.
Vitamin D is found in some foods, such as meat, fish, eggs, but they all have an acidifying effect that reduce its absorption. Vegetarians, vegans, are most at risk and should take it in the form of a supplement.
Although we think that the lack of vitamin D is linked to menopause and andropause we 
must be careful with children, especially those who live in states where the sun is not very present. The kindergarten, school, keep them at home in the heat and cover them too much during the winter months prevents the synthesis of vitamin D with the risk of fragility bones.
Fortunately, there are many foods fortified with vitamin D, so try to give their to your children.
The active is the vitamin D3. The dose ranges from 200 to 1000 IU (international units) a day, but it certainly varies according to your needs, nutrition, age and sun exposure.
If you are suffering from fatigue, feeling bone,andmuscle aches, or any of the diseases I have mentioned you have to go to your doctor recommended to perform the blood test, according to the result he can advise the proper dose of vitamin D to be taken to achieve the right balance.
