What milk and cereal should I eat with stage 4 and is there a vitamin that should be taken to lower creatinine?

Nutrition needs in CKD stage 4 vary from person to person. But in general, the recommendation is to choose lower protein options. For milk, choose a nut milk without added protein such as almond milk. Be sure to check the label and avoid any with additives especially phosphorus and potassium additives. Oatmeal is a good breakfast choice, but the instant oatmeal packs tend to have phosphorus and potassium additives. Try making your own: use a quick cook oatmeal, add a bit of brown sugar (1 teaspoon) and cinnamon or any other spice flavoring, maybe try adding little maple syrup instead of the brown sugar. Add fresh/frozen berries or a chopped apple which add flavor and texture. Vitamins are tricky. I do not know of any vitamins that help lower creatinine. Also vitamins are not regulated by the USDA or FDA, so when choosing a vitamin, first talk with your doctor and if given the green light look for a vitamin that is 3rd party verified. USP and NSF are 2 of the 3rd party verifying organizations that are creditable. Talk with your doctor, they might prescribe medications such a sodium bicarbonate to help preserve kidney function. I do not recommend taking any over the counter supplements, including sodium bicarbonate or vitamin without speaking with your doctor first.