A main key (starter) of the immune system - a lack of it is like starving the immune system, for the army that is supposed to protect the body, a large number of studies have found a clear connection between its level in the blood and the risk of severe corona disease and mortality. (Most seriously ill patients and those who died from the disease had very low vitamin levels, compared to people of the same age group who passed the disease in a milder form) Essential for bone health - the balance of calcium in the body as well as for improving the absorption of calcium from the intestines into the bloodstream. Lowers the risk of asthma and allergies. Lowers increased risk of preeclampsia