A lot of researchers are blaming all of our current health problems on vitamin D deficiency. Vitamin D deficiency is a nation-wide epidemic. Doctors are seeing cases of rickets for the first time in decades. Many attribute the rise of food allergies/autism/autoimmune disease in the last 20 years to the advice to "stay out of the sun" and "wear sunblock" that started in the 80's.
Here are some articles from pubmed on vitamin D deficiency:
Regional differences in EpiPen prescriptions in the United States: the potential role of vitamin D
The vitamin D epidemic and its health consequences
Autism and vitamin D
I am proud to say I haven't really put sunblock on my children all summer (ok, a little on the baby). I also force them outside for 20 minutes in the mid-day sun to soak up some rays. For more info visit: The Vitamin D Council.
On a positive note, HERE is a wheat, dairy, soy, egg, and nut free pop tart recipe.