Streep was in Bloomingdale to help raise money and awareness at the Charlie Foundation's Inaugural Gala.
That charity raises money to help find a cure for pediatric epilepsy.
Streep starred in a 1997 film called First Do No Harm, which centered on a boy with severe epilepsy.
"I'm really proud to be associated with the foundation to have played some small part in getting the word out the ketogenic diet and all the protocols that are associated with it," Streep said.
The ketogenic diet that Streep refers to has been beneficial to more than half of the children who've tried it.