Avocados are very healthy. They are full of vitamins, minerals, and phytochemicals, and they are also a very healthy source of fats. Unfortunately, they may not be so good for the kidneys. Avocados are very rich in potassium, which can be difficult for the kidneys to process. Individuals with kidney problems will most likely be told by their physicians to avoid too much potassium, so it's okay to say no to the guacamole once in a while. Typically, restrictive renal diets are low in sodium, potassium, protein, and phosphorus, all of which are difficult for kidneys to process. Even with healthy kidneys, diets high in these substances can lead to kidney disease later in life.