Parrots like humans need a good diet to live a long happy life. A parrot should be  fed a diet with lots of fruits and vegetables and low in fat and sugars.  Most food that are good for humans are good for your pet birds as well. (NEVER FEED YOUR BIRD CHOCOLATE, AVOCADO,  AND CAFFIENE) Birds should never be fed a seed only diet because a diet of seeds only can lead to weight gain and other health problems. Talk to your avian veternarian for the  best diet for your bird. Birds usually like foods such as pasta and other human grade cooked foods WITHOUT SEASONINGS!
Food brands I recommend are as follows:
1. Zupreem
2. Harrisons
3. Roudybush
4. Totally Organic
5. Bird Street Bistro
Most avian veternarians will tell you to use Zupreem because it is a complete avian diet. If your bird will not eat Zupreem then try it on another high quality food such as Harrisons or Roudybush. NEVER BUY BIRD FOOD AT THE GROCERY STORE. ALWAYS CHECK THE DATE ON FOOD BEFORE BUYING!
When buying food for birds be sure it is the correct food for your bird species and size. In some cases foods may not list all species it can be fed to in this case ask a trained avian specialist or veternarian. Some websites such as have a shop by species option to help you with this. You can also buy food mixes you can cook for your bird such as Bird Street Bistro and Dr. Harveys What's Cooking.

Vitamins: With a good diet chances are your bird will not need a extra vitamin added to it's food or water but in some caes a vet may think it needs one. BEFORE USING ANY VITAMINS TALK TO YOUR AVIAN VETERNARIAN!!!