A new study finds out why curcumin might help protect against dementia, and links two factors associated with Alzheimer’s and Parkinson’s diseases: DNA damage by reactive oxygen species (ROS), and excessive levels of copper and iron in parts of the brain. It turns out that high levels of copper or iron help generate large numbers of ROS and interfere with DNA repair.

While small amounts of iron and copper are vital, these are normally bound by proteins. However, when there’s too much, it can overwhelm the proteins and the result is "free" iron or copper ions circulating in the blood, able to initiate chemical reactions that produce reactive oxygen species. Moreover, the free copper and iron also interferes with the activity of two enzymes that repair DNA, NEIL1 and NEIL2.

However, the curry spice curcumin binds to iron and copper and was extremely effective in protecting the NEIL enzymes from the metals.