Often the subject of grit comes up since many birds eat it in the wild and it is essential for digestion in some species. Is this the case with budgies and other parrots? Are there any potential problems with offering it, or any benefits?

Well lets first think about what the purpose of grit is in the gizzard of a bird. Its purpose is to help break through the hard husks and shells of seeds that the bird has swallowed in the gizzard, since many species of birds swallow their seeds whole such as pigeons, chickens, quail etc. What about budgies? 

The picture on the left is a common site to any budgie owner, and it is quite obvious that unlike some other bird species parrots, including budgies, husk the shells off of each seed they eat 

before swallowing them. Because of this they do not need grit the way some other birds do. In fact it can pose a danger to their health. Please note this quote from Avian Web.com:

"Grit is an important aid in helping certain birds, such as finches, canaries and other passerines, digest food - but this does NOT apply to parrots. Parrots have a smaller exit opening from the stomach into the intestines, so grit remains trapped in the stomach causing internal blockage. The birds may show neurological symptoms, weight loss, and eventually death."
Quote from: http://www.avianweb.com/birdnutrition.html

Grit is not digested, and thus is of very little nutritional value or benefit. Offering a cuttle bone and mineral and or iodine block will give your budgie the other essential vitamins and nutrients it needs in addition to a well balanced diet of seeds, pellets, veggies and fruit among other things:


"Grit is Not Required By the Normal, Healthy Psittacine or Passerine Bird
Grit, usually defined as a granular, dense, insoluble mineral material (generally granite or quartz), is required for birds that consume whole, intact seeds. Examples of some birds requiring grit are pigeons, doves, free-ranging gallinaceous species (Red Junglefowl, Common Turkey, Helmeted
Guinea Fowl, Domestic Fowl, quail, megapodes, pheasants, grouse, and more) and ostriches. Notice that parrots, canaries and finches aren't on the list. The smaller psittacines (budgies, cockatiels, lovebirds and parrotlets) may overeat grit when they aren't feeling well, and this may result in an impaction of the gizzard. Psittacines and passerines will get all the minerals they need from a
balanced diet."  
Quote From: http://www.exoticpetvet.net/avian/20facts.html

If you do decide that you would like to have grit in your budgies diet, offering limited amounts of soluble grit is best. Oyster shell grit is an example of something you can offer that will digest over time and in the process provide some nutrients.

"Dr. Robert Linville, DVM of Vallejo, California states, "Birds that hull their seeds do not require grit. Although they seem to enjoy picking at it, overeating grit can irritate and even obstruct the gastrointestinal

tract. If grit is used, it should be provided in very small amounts. A few grains of grit a week is more than enough. We recommend a firm no-grit policy (exception is passerine birds such as Finches and Canaries)."
Quote from: http://www.holisticbird.org/pages/dgrit.htm