The average reported boron intake in the American diet is 1.17 milligrams per day for men, 0.96 milligrams per day for women and 1.29 to 1.47 milligrams per day for vegetarians. High boron content foods include peanut butter, wine, grapes, beans, and peaches. 2.5 to 6 milligrams have been taken by mouth in studies. For psoriasis, 1.5% boric acid with 3% zinc oxide ointment applied to the skin as needed has been studied.