Immuni-D.

Immuni-D, pronounced like immunity ;)

Vitamin D is important for healthy operating immune system. 

It is immuno-stimulating. One way in which it works is by initiating the synthesis of anti-microbial peptides in white blood cells. (Background information: anti-microbial = anti-bacterial/viral; peptide = protein; white blood cells = key players in the immune system).

The second way it works: it helps to mature T cells.  (Background information: T cells are a type of white blood cell that is plays a role in regulating and initiating attacks against invaders).

Where can you get vitamin D?  The sun is the best source, with supplements (liquid drops) being the second best, fortified foods (some orange juices, grains, yogurts, mylks, and milks) are third best, and lastly, regular food sources rank fourth (seafood, egg yolks, and mushrooms).

It is hypothesized that a lack of vitamin D is one of the reasons why we often get sick in the colder, darker months, and why we stay much healthier in the warmer, sunnier months.  Thus it is good to supplement vitamin D from October to April.