Zinc – The right form, the right amount
AREDS and AREDS 2 used Zinc oxide in their formulas for macular degeneration therapy.
The Office of Dietary Supplements at the National Institutes of Health states that no form of zinc works better or is better absorbed, despite the advertising that suggests that there are marked differences.
AREDS in 2001 used 80 mg of daily zinc oxide. The zinc worked nearly as well as the entire AREDS formula, but there were significant numbers of people with gastrointestinal and genitourinary side effects.
AREDS 2 found no significant difference comparing 25 mg versus 80 mg daily zinc oxide. Cupric oxide is put in these formulas not for macular degeneration, but to avoid a zinc-induced anemia. So when zinc is reduced, copper can be reduced.