One of the most important things you can do for your kidneys is to not spike your blood sugar. When your blood sugar goes beyond a healthy level it causes advanced glycation end products (AGE).
Glycation happens when sugar molecules floating around in the blood attach to the protein molecules on the surface of cells, causing those proteins to lose some of their function. Normally, proteins that are embedded within cell membranes and that protrude to the outer surface of the cell have numerous vital functions, such as hormone reception, communication between cells, and cell identification. However, when a surface protein becomes incapacitated by glycation, it is changed into an AGE. Instead of helping cells communicate, the affected protein becomes a problem. Once an AGE is produced, it can actually speed up a chain reaction that furthers the damage to tissues (for example by promoting the formation of free radicals, or by affecting gene expression). When there is a consistently high glucose level in the blood the kidneys must work over time in an attempt to remove it. Over a period of time AGE destroys the glomeruli (the filters of the kidneys) and they fail.
Protecting your kidneys by keeping your blood sugar in balance and taking an anti-oxidant supplement such as Grape seed extract will help them do their job.
Parsley is an excellent diuretic and as such it is used for edema and urinary stones. It is believed to increase the elimination of waste products like urea, and other acidic metabolites, and thus used for gout and arthritis. Fresh parsley juice is easy to make by taking 1 cup of chopped parsley and adding it to 2 cups of filtered water in a blender. Blend on high until the parsley breaks down and is easy to drink. Add 1 tbsp. of lemon juice for a refreshing taste. This is a wonderful way to start the day and includes healing nutrients beta-carotene, vitamins A, B2, C and E, calcium, potassium, and iron.
Nettle tea is another wonderful kidney remedy. It has been shown to increase the elimination of the waste products such as uric acid. It is a diuretic, and has been found successful in managing the symptoms of benign prostate hypertrophy, particularly in combination with saw palmetto. It is also rich in minerals and has been used as a blood tonic in traditional herbal medicine.
With both these herbal remedies, you must have functional kidneys to use these remedies due to its high mineral content. Consult your health care provider for more guidance.