The kidneys are two organs located in the lower part of the back that are essential for excreting wastes from the body. Nephrons are functional units in the kidneys that contain a structure of capillaries, which work to filter particles out of the blood. These wastes are added to fluid to create urine, which is then excreted out of the body. Normally, the kidneys filter wastes out of the blood but leave protein. Low levels of protein in the body can also affect how the kidneys function.
Protein
Protein is an important nutrient that forms a basis for many different parts of the body including the skin, hair and nails. It is found in foods such as red meat and poultry, dairy products, beans, lentils and nuts. Proteins are made up of amino acids that are connected by peptides. The proteins are broken down into their amino acids during digestion and are then used for making new protein or for energy. Most people get more than enough protein in their diets; protein deficiency is rare in developed countries. Alternatively, for those with illnesses that cause difficulties digesting protein, or for vegetarians who do not eat enough plant-based foods with protein, a deficiency of this nutrient is possible.
Kwashiorkor
Significant protein deficiencies, often found in developing countries, cause a condition known as kwashiorkor. The condition occurs among those with very little protein in their diets. Kwashiorkor is typified by wasting of the muscles and edema, skin changes and damage to the liver cells. Low levels of the protein albumin can cause the kidneys to try to keep some water and sodium in the bloodstream, resulting in edema. This kidney response causes the swelling often seen among those with kwashiorkor, including that in the limbs and in the abdomen.
Kidney Disease
Some conditions can destroy the tissue of the kidneys, disrupting the filtration system. When the nephrons in the kidneys are damaged due to diabetes, high blood pressure or some types of congenital diseases, the kidneys begin to excrete protein into the urine. This occurs when a protein in the blood known as albumin is added to the rest of the wastes being excreted. Kidney disease can prevent the kidneys from regulating fluid levels, which leads to greater volumes of fluid circulating through the bloodstream. The capillaries can begin to leak some of this fluid into the surrounding tissues, causing swelling.
How Much Protein
If you have a protein deficiency, your doctor or dietitian can guide you as to what kinds of foods you should eat. This will depend on what your kidney function is and whether or not you have kidney disease. Low levels of protein may help keep kidney disease from progressing, but some doctors want patients to have protein in their diets to avoid malnutrition. According to DaVita, a medical provider of dialysis and kidney care in the United States, people with kidney disease should take in 0.75 grams per kilogram of body weight for moderate chronic kidney disease to avoid deficiency. For those who do not have kidney disease, adult women should receive 0.75 g/kg daily, while adult men should take in 0.85 g/kg daily to avoid deficiency.
