The the connection between iodine and dermatitis herpetiformis is briefly described by the following excerpt from a resource guide of the Gluten Intolerance Group of North America:

As background, for those who are not familiar with Dermatitis Herpetiformis, the following description comes from a resource guide of the Gluten Intolerance Group of North America:

When my husband was diagnosed with dermatitis herpetiformis last November, he went to visit a expert in dermatitis herpetiformis, Dr. John J. Zone, at the University of Utah (USA). The written instructions Dr. Zone gave him included the following statement:

It is not necessary for dermatitis herpetiformis patients to eliminate iodine completely from their diet, merely to avoid foods high in iodine as described above. Dr. Zone also explained that dermatitis herpetiformis patients need not avoid iodine indefinitely. Iodine is an important mineral for our bodies. dermatitis herpetiformis patients can stop avoiding iodine when their rash symptoms clear up which can take anywhere from a few months to a couple of years on a gluten-free diet.

More about iodine: