Selenium and Psoriasis:
Selenium deficiency is pretty common in dandruff, psoriasis, eczema, tinea (age spots), athletes foot, jock itch, seborrheic dermatitis, candida infections, hypothyroidism.
There are different yeasts, of course, trichophyton, mallasezia furfur, candida and others. Some spots may itch, others may not. I suspect rosacea may be a yeast problem as well (combined with Demodex mites eating the yeast).
Yeast needs oxygen, and Selenium is a very powerful antioxidant (500x stronger than vitamin e). Kill the oxygen supply, with Selenium, and you kill the yeast.
A good source of Selenium is brazil nuts(orally), or Dandruff Shampoo(topically). Selenium works with iodine (and is thyroid protective). Taking one alone, though could cause a deficiency of the other, theoretically.
Seborrheic dermatitis is an advanced form of dandruff, possibly caused by fungi colonizing on the scalp
"* To treat seborrheic dermatitis, look for shampoos that contain coal tar, zinc pyrithione, selenium sulfide or salicylic acid."
Note: head and shoulders selenium sulfide shampoo says on the bottle that it "treats seborrheic dermatitis".
Trace element status in eczema and psoriasis
"Concentrations of zinc, copper and selenium were determined in plasma and leucocytes from 23 patients with psoriasis and 24 with eczema."
"Concentrations of selenium in whole blood, plasma and leucocytes were significantly reduced in both groups. This finding may be of importance in relation to the effect of free radicals on skin."
Selenium sulfide: adjunctive therapy for tinea capitis
"Selenium sulfide lotion used as a shampoo has been shown to be an effective adjunctive agent to griseofulvin in the treatment of tinea capitis(head)."
How to treat Malassezia furfur (tinea versicolor) in humans?
Medical Care: Patients should be informed that tinea versicolor is caused by a fungus that is normally present on the skin surface and is therefore not considered contagious.