Another factor:

Our skin is renewed using fatty acids from our diet. Primarily the Omega-3 fatty acid alpha linolenic acid from Flax oil, and some other sources, like canola oil, walnuts. You have to actively seek out ALA sources. Some "smart" foods now have flax in them.
Some breads ( I am using a flat bread now with flax)
some cereals (will list on the labels or front of box)
Smart Balance products like peanut butter, and mayo have Omega-3 s in them.

If we do not consume enough Omega-3 (and not fish oil which is an end stage product of ALA intake), we cannot renew our skin.

Adequate intake of ALA is important for maintaining our mucus membranes, and skin. Including the lining of the stomach which is dependent on this nutrient.
Testing over the years for ADHD and other neuro problems has shown that in USA we consume far more omega-6's than 3's. Up to 1:25 omega-3 to 6. Optimum levels should be 1:1 up to 1:5.
I have an EFA thread here on this subject:
http://neurotalk.psychcentral.com/showthread.php?t=6092

If you have deep calluses on your feet, they will change with this dietary change. That is only one example.
My son's acne cleared up with only 1 flax oil a day. I also removed transfats, back then, and now that is being done for us by the government restrictions on it. Today we have infant formula with DHA added, and even pet foods that use this technology. (this was not true 10 yrs ago) So if you'd do it for your dog or cat, you need to do it for yourself too!