25446
Oxalic acid on its own interacted with Ca ( 2 + ) at low concentrations , whereas polyphenols and protein did not .
 Oxalic acid, Ca ( 2 + ), polyphenols
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Oxalic acid, Ca ( 2 + ), polyphenols