Your kidneys are bean-shaped organs that perform many important functions.
They’re in charge of filtering blood, removing waste through urine, producing hormones, balancing minerals, and maintaining fluid balance.
There are many risk factors for kidney disease. The most common are uncontrolled diabetes and high blood pressure.
Alcoholism, heart disease, hepatitis C virus, and HIV infection are also causes ( 1 ).
When the kidneys become damaged and are unable to function properly, fluid can build up in the body and waste can accumulate in the blood.
However, avoiding or limiting certain foods in your diet may help decrease the accumulation of waste products in the blood, improve kidney function, and prevent further damage ( 2 ).
Dietary restrictions vary depending on the stage of kidney disease.
For instance, people who are in the early stages of chronic kidney disease will have different dietary restrictions than those with end-stage renal disease, or kidney failure.
Those with end-stage renal disease who require dialysis will also have varying dietary restrictions. Dialysis is a type of treatment that removes extra water and filters waste.
The majority of those with late- or end-stage kidney disease will need to follow a kidney-friendly diet to avoid the buildup of certain chemicals or nutrients in the blood.
In those with chronic kidney disease, the kidneys cannot adequately remove excess sodium, potassium, or phosphorus. As a result, they’re at higher risk of elevated blood levels of these minerals.
A kidney-friendly diet, or renal diet, usually involves limiting sodium and potassium to 2,000 mg per day and limiting phosphorus to 800–1,000 mg per day.
Damaged kidneys may also have trouble filtering the waste products of protein metabolism. Therefore, individuals with chronic kidney disease in stages 1–4 may need to limit the amount of protein in their diets ( 3 ).
However, those with end-stage renal disease undergoing dialysis have an increased protein requirement ( 4 ).
Here are 17 foods that you should likely avoid on a renal diet.
In addition to the calories and sugar that sodas provide, they harbor additives that contain phosphorus, especially dark-colored sodas.
Many food and beverage manufacturers add phosphorus during processing to enhance flavor, prolong shelf life, and prevent discoloration.
Your body absorbs this added phosphorus to a greater extent than natural, animal-, or plant-based phosphorus ( 5 ).
Unlike natural phosphorus, phosphorus in the form of additives is not bound to protein. Rather, it’s found in the form of salt and highly absorbable by the intestinal tract ( 6 ).
Additive phosphorus can typically be found in a product’s ingredient list. However, food manufacturers are not required to list the exact amount of additive phosphorus on the food label.
While additive phosphorus content varies depending on the type of soda, most dark-colored sodas are believed to contain 50–100 mg in a 200-mL serving ( 7 ).
As a result, sodas, especially those that are dark, should be avoided on a renal diet.
Dark-colored sodas should be avoided on a renal diet, as they contain phosphorus in its additive form, which is highly absorbable by the human body.