I was looking into catalase and hydrogen peroxide.
CAT is an enzyme that breaks down H2O2. As we age our production of CAT decreases, and the excess H2O2 does various harms to our bodies, including bleaching of skin and of hair follicles.
In India a topical catalase treatment was developed for vitiligo, an unpleasant skin disorder. The treatment didn't work as expected until turmeric (active ingredient curcumin) was removed from the diet: http://www.vitiligo.eu.com/turmeric.php
Wot? Curcumin is an anti-oxidant and boosts catalase. But it looks like the dose Indians typically take in their diet may push it to pro-oxidant behaviour that inhibits catalase. Here's the general view of the two extremes: http://books.google.co.uk/books?id=KJzJ5obKnwwC&pg=PA254&lpg=PA254&dq=curcumin+catalase&source=bl&ots=w-noTZ4b1z&sig=Q7cPhUapJ2onUseyM-WKzZULJc4&hl=en&sa=X&ei=NPf_UdqSK-Xb0QWY64GgCw&ved=0CHUQ6AEwCTgK#v=onepage&q=curcumin%20catalase&f=false
So how much is too much? The most satisfactory answer I could find looks like maybe 6g - a heaped tablespoon? There are 2 studies footnoted, but it's not clear: http://examine.com/supplements/Curcumin/
I take a tip of a teaspoon everyday, so I guess that's well outside the pro-oxidant range.
Anyone else have views? I know turmeric is generally recommended on this site.
(There is a "how much turmeric" thread already, but I think this info deserves a new one. Plus the information on catalase is interesting.)