We will be getting a new puppy in 4 weeks. The breeder sent us a list of things to get (toy, leash, x small harness, food bowls, crate). The breeder also sent a link for food and a vitamin.  Can the breeder require use the certain type of food or vitamin?  We take very good care of our animals.  In the past we had a sick dog and spent a small fortune monthly on food, vitamins and medicination. So we will do what ever is needed. But can a puppy contract state a buyer has to use a certain type of food or vitamin?  I feel like the breeder gets a percentage of the vitamin sales.  The vitamins have a code we must use to purchase.

What is the food and vitamin they are stating you will need?
Normally a pup would not need additional supplements if their food is good quality and well balanced.
You should feel comfortable to be able to ask your breeder what the vitamin is for.

It is a good idea to use the food the breeder has been using to avoid upset tums when you bring the pup home. it would them usually be up to you to transtition them onto what you want to feed, but there may be a reason that the breeder want you to feed something specific. Again, you should feel comfortable to ask the breeder these questions.

This is interesting because I've recently seen a similar thread online about vitamins that a breeder (not in the UK) was getting their puppy buyers to purchase in this way. It ended up being kind of like a pyramid scheme and you were actually buying through the breeder- probably what the code is for.

The only thing a growing puppy needs is a quality, balanced diet. The only thing I would consider adding would be omega oils, but not necessary.

Not worried about the food. It is a responsible price and sold at a local pet store.

It is the vitamin I am curious about. The vitamin is Nuvet. I plan to ask the breeder tomorrow what the vitamin is.

I would not assume that a food being reasonably priced and sold in a pet store means that it is good quality. Maybe see if you can find it on the All About Dog Food website so you can better judge.
If it is indeed a good quality food, then no supplements are required for an otherwise health pup.
NuVet is a supplement containing many ingredients rather than being a 'vitamin'.

I think a breeder can strongly recommend a food because it's what the pups have been raised on, and what they know to work well with their dogs/lines.  (They can't MAKE you use it or do anything legally - they can only recommend.)

As others have said, a vitamin/mineral supplement shouldn't be necessary if you're using a decent balanced food - that should have all you need in it.

Just looked up nuvet .it seems to be amixture of various vitamins and minerals all of which should be in any decent food they are feeding their pups anyway. 
I would do as the others have said use the current food short term and then change to what u feel is best for the pup.supplemnts arnt usually needed in a healthy pup

The allaboutdogfood site is worth looking at unless u know what u want to feed. I have changed all my dogs to raw after a few weeks to settle in . I would be very surprised if a breed stipulated in the contract about food and unless u both agreed I wouldn't be able to purchase the pup jmo  .

For me, all a breeder can do is recommend.   It's usually best to keep the puppy on the food it's been eating up to the time you bring him home, but after that, given that if you do switch it must be done gradually over at least a week, mixing the new with the old, it's up to you.   Just know that if you do alter what the breeder recommends and it goes pear-shaped, you can't go back to them to 'complain'!!    Most good breeders know what works best for their particular bloodline.   I've had a vet rubbish the diet sheet I always gave with our puppies and that really made me MAD, especially as what was suggest wasn't anything I'd have recommended and what was tried and tested with our puppies over many generations.

Was a time back when, that people would be advised to use a calcium product called Stress, but with the advent of good quality puppy food, none of that was necessary.

Unless there's a special need for the puppy you will be buying to have 'extras' I'd just take her recommendations as advisory - what she has worked with and which has worked.   But as said, if you decide to ignore her advice, you really can't expect to get back to her if your puppy has problems after you've changed the diet.

once you have brought the puppy it's yours to do with as u like. Just like a toaster, if I sold u mine I could not then say you can only toast white bread in it.

As others have said if the diet is good extra vitamins are not needed and can I fact be harmful as the pup may be getting to much of them.

Does the puppy contract state you have to keep feeding the same food and vitamins, or is it just what she uses and she has given you a link if you wish to buy more?

If it's part of the contract, I would ask what will happen if you change foods? If the contract is to stringent saying what you can't do with your own dog, I'd look for another breeder

I don't think a contract like that would be legally enforceable but yes, it doesn't bode well for a good breeder-puppy owner relationship...