Older adult believes their food has been poisoned. Any suggestions?

My MIL went though a spell ( well before she really went off the rails) when she thought everyone was trying to poison her. She would pack up her meal on a tray and take it to the bathroom with her if she had to go... No lie!!

Tell a little white lie and say you had her doctor check it out and all good!

Have him/her checked for a UTI. The first indication when my aunt had one was a man in her room, and music coming from wires in her wall. She unplugged everything. and could not be calmed by anything I told her. Urine showed physical signs of infection, so the doc gave her antibiotics. Test later came back negative, however, no more voices, music, people in her room, etc. after the 2nd antibiotic.

I dealt with this with my father. He had severe OCD. Very serious.

Tell them you will take care of it. Take the opportunity to go through the cabinets and discard what's expired, donate what's unloved, and bag separately what you want to keep. It all goes to a separate part of the car (expired in trash). Next day bring back the stuff to keep and donate the other. Unfortunately, they won't remember that you did this. It's paranoia and is because the brain is broken. 

Provide food and drink that are sealed like fruit cups, yogurt, small juice containers.

You could "check" the food by tasting it first.

They’re spooked by so many things... germs, someone breaking in, etc. I like grammy’s reply... be creative and flexible.

Tell her you took it to a lab and it checked out fine. Therapeutic lies work well.