Cats should not eat marshmallows. Their digestive systems are adapted for meat-based diets, and marshmallows offer no nutritional value. can cats eat marshmallows The sugar and additives in marshmallows can upset their digestive tract. To maintain your cat's health, avoid sharing such human treats. Instead, provide appropriate cat food that meets their dietary requirements. Consult your vet if you suspect your cat has consumed marshmallows or other non-cat foods.