The kidneys contain specialized cells, called glomeruli, surrounded by a bed of small blood vessels, called capillaries. The glomeruli act as small filters, removing toxins from the blood in the capillaries for excretion in the urine, while retaining essential nutrients within your bloodstream. The foods you eat have an effect on a number of tissues within your body including your kidneys. Consuming a diet rich in unhealthy foods can increase the strain on your kidneys and eventually damage structures within your kidneys over time.
High sodium foods can damage your kidneys. Sodium acts as a preservative for many processed food products and also acts as a flavor enhancer. Your kidneys balance the amount of sodium stored in your body. However, if they can’t eliminate enough sodium, the sodium accumulates in the blood and because sodium attracts and holds water, your blood volume increases, causing high blood pressure. Over time, consistently high blood pressure can damage the blood vessels surrounding the glomeruli in your kidneys, diminishing kidney function and leading to kidney disease. To lower the levels of sodium in your diet, avoid consuming processed foods, fast food, and cured meats such as bacon.
Eating foods high in sugar can also damage your kidneys over time. After consuming sugary foods, your body breaks down and absorbs carbohydrates from your meal, increasing the level of simple sugars, called glucose, in your bloodstream. If you eat sugary foods regularly or in large quantities, this increase in blood sugar can lead to increased blood pressure, which can strain your kidneys. In addition, a diet rich in sugary foods increases your risk of diabetes, increasing your risk of diabetic kidney disease. You can help protect against sugar-related kidney diseases by avoiding candies, baked goods, and other sugary foods and condiments, as well as monitoring your carbohydrate intake to help control your blood sugar if you already suffer from diabetes.
Consuming high levels of oxalate-rich foods may play a role in the formation of kidney stones, a common kidney disorder. Kidney stones develop from minerals found in your bloodstream that begin to crystallize within the tubules of your kidney, eventually forming a stone. The presence of high levels of oxalate can promote the formation of some types of kidney stones such as calcium oxalate stones. If you have suffered from kidney stones in the past, do not consume oxalate-rich foods including rhubarb, concord grapes, strawberries, sweet potatoes, spinach, summer squash, beets, leeks, tea, coffee, nuts and tofu to avoid recurrence.