And so a food that is synthesized turns out to be an incomplete source of nutrition. Conversely, when nature puts the food together it contains all the elements - vitamins, minerals, amino acids, etc. Many birds are not being fed well. A synthetic diet or pelleted feed does not contain all the parts needed to make it complete. When you look at the label it reads like a who's who in vitamins, minerals and so forth, but in actual fact it is really deficit in a lot of things.
Incomplete vitamins create vitamin deficiencies.
Many folks think they're doing the correct thing when feeding an incomplete pelleted diet to their birds, but in reality these fabricated diets can worsen a condition or the state of health. Just by taking a bird off pellets and providing them with whole foods it has been discovered that an overwhelming change in health for the better takes place - for example, freedom from disease, calmness, and responsiveness to its human companion. Of course, a whole foods diet must be varied, balanced and from a wide selection of foods. The more diverse your bird's diet is the better. They are isolated synthetic vitamins, minerals, amino acids and so forth along with a few grains, seeds, etc.