My cat throws up every few days, could it be related to food (cat chow)? Or something enviromental? Or..?

She's a mixed breed, medium hair, small cat, about 7 years old.

This has been going on for years, she doesn't seem to be in distress, other than throwing up. It's gross and I'm tired of it.

Give your cat a half a tea spoon of hydrogen peroxide
one time a week in her food for 2 months she sounds like she has a blockage and this should clear it up

Make sure you have no plants that are poisonous to cats in your neighborhood or backyard, and try testing for worms.

Cats do naturally regurgitate fur balls from grooming themselves. So, naturally, there may be food in the mix. I've never known a cat that DOESN'T do this. There are fur ball remedies you can try, but I would ask a vet for a recommendation.