By Dr. Brian McDonough

PHILADELPHIA (CBS) — We are always trying to learn why we are allergic to certain substances and not allergic to others.

Certainly this has all a great deal to do with our immune system.

According to a new report in the Annals of Dermatology, patients with a condition called severe atopic dermatitis, this is associated with dry skin intense itching and reactions to dust mites and other common allergens, it may all come down to the presence of vitamin d in our system.

According to the report, there is an odd association between patients with low serum vitamin d levels and an increased risk of house dust mites sensitization.

The reasoning is fascinating.

Apparently it has to do with the fact that the dust mites are able to break through a broken skin barrier, which is the result of the reduced amount of vitamin D.