The kidneys are sophisticated organs that remove waste and toxins from your blood. Every day, they process about 200 quarts of blood and remove 2 quarts of waste products and water. Normally, your kidneys have little trouble filtering out everything that is presented to them. Even a moderate decline in kidney function of 30 to 40 percent is barely noticeable. However, damage to the filtration units of the kidneys, known as the glomeruli, can affect their ability to handle protein from tuna and other animal products. This condition is called proteinuria, and it's a sign of chronic kidney disease.
Protein in the Blood
Proteins are a group of molecules upon which every cellular process in your body depends. In the blood, they help protect your body from infection, stop blood clots and regulate the amount of fluids circulating. The type of protein in the blood is a water-soluble substance known as albumin. The liver obtains protein from the foods in your diet, including tuna, and converts it into albumin. A single can of white tuna, which contains 30 to 40 g of protein, will therefore increase the amount of albumin circulating in your blood. The typical protein requirements are not great --- 56 g for men and 46 g for women --- so the consumption of tuna represents a significant portion of your daily protein intake.
Proteinuria
Most proteins are usually too big to pass through the glomeruli. If albumin does manage to pass through, however, it can result in major leakage of protein from your body. When your kidneys are deteriorating, this is the fate of the protein that you consume from tuna. The major symptom of proteinuria is known as edema, which means that your blood will no longer be able to soak up enough fluid, causing swelling in the hands, feet, abdomen and face.
Research
According to a 2010 study published in "The Journal of the American Medical Association", patients with higher levels of proteinuria and lower levels of glomerular filtration capacity have an increased risk of all-cause death, heart attack and a progression to kidney failure. Tuna contributes such a large amount of protein in your diet that it will only worsen the problem over time.
Causes and Treatment
People with diabetes, hypertension or certain genetic factors are at the greatest risk for proteinuria because they harbor conditions that can damage the glomeruli in the kidneys. Damage is rarely cured or reversed, but a doctor may recommend restricting protein in your diet to prevent further damage. Protein is so essential that you cannot completely remove it, but you can control the sources of protein and work with a dietitian to construct a diet plan that conforms to your needs. Removing tuna from your diet is one such step that you can take.
References
- National Kidney and Urologic Diseases Information Clearinghouse; The Kidneys and How They Work; February 2009
- National Kidney and Urologic Diseases Information Clearinghouse; Proteinuria; March 2009
- Centers for Disease Control and Prevention; Protein; February 2011
- "Journal of the American Medical Association"; Relation Between Kidney Function, Proteinuria, and Adverse Outcomes; Brenda R. Hemmelgarn, et al.; February 2010
