In Turkish cuisine there is a popular food called "tahin pekmez" (tahini with grape molasses).
According to a 2017 article on some Turkish news site, mixing these is supposedly counter-productive due to the calcium in the tahini bonding with the iron in the molasses and becoming unusable to the human body. From what I can tell, the article doesn't cite any study for this claim.
Obviously I'm inclined to believe that the claim is click-bait, but I thought let's give it a chance and ask people who know their chemistry.
I hope this isn't too basic or otherwise off-topic for Chemistry StackExchange.