All of these can and almost invariably will, cause serious problems over a period of time and can contribute to a very early death. Cheese contains valuable calcium and vitamins, however the benefits from these are considerably outweighed by the disadvantages of the excess fats and salts. Ideally, a few light scrapings can be scattered over food as an occasional treat to add flavouring. Milk is sometimes given along with cereals as a regular breakfast 'treat'. In time, severe allergies and potentially life threatening conditions can occur, including acute inflammation of the entire gastro-intestinal system resulting in very severe diarrhoea.
Milk has absolutely no part in the diet of a parrot.
Conversely, natural, live, low-fat yoghurt is one of the very few, beneficial dairy products and can be safely offered from time to time. Many breakfast cereals are fortified with vitamins and these can be highly injurious, causing chronic hyper-vitaminoses in time. No foods which are fortified with human vitamin and mineral requirements should ever be offered to parrots. These additives are totally unsuitable and the amounts contained, excessive from an avian point of view. Above all, cereals with 'added iron' must be avoided since iron accumulates in the blood system, gradually rising to toxic levels.