Kidney health is crucial because kidneys filter waste, balance minerals, control blood pressure, make red blood cells, and keep bones strong, all of which affect many body functions. When kidneys are unhealthy, waste and fluid can build up, leading to issues like heart disease, anemia, high blood pressure, and mineral/bone disorders, affecting nerves, muscles, and the ability to breathe. 

Impact on specific body functions

• Cardiovascular System (Heart & Blood Vessels): Kidneys regulate blood pressure by releasing hormones like renin and balancing fluid and salt levels. Impaired function can lead to high blood pressure, heart disease, and stroke.

  • Kidneys and the heart share a close relationship. Damaged kidneys can't manage blood pressure well, causing hypertension (high blood pressure) which further damages blood vessels and strains the heart. The accumulation of fluid can lead to swelling and potentially fluid in the lungs (pulmonary edema) or around the heart (pericarditis), significantly increasing the risk of heart disease, heart attack, and stroke.

• Blood and circulation: Blood System: Kidneys produce the hormone erythropoietin (EPO), which tells bone marrow to make red blood cells. Kidney disease can lead to decreased EPO production, resulting in anemia (low red blood cell count), which causes fatigue, weakness, and shortness of breath.

• Skeletal System (Bones): Kidneys are vital for bone health by helping to balance minerals like calcium and phosphorus and by assisting in vitamin D activation. Problems can lead to a mineral and bone disorder.

  • Kidneys activate vitamin D, which is necessary for the body to absorb calcium and keep bones strong. When this process is disrupted, it leads to an imbalance in calcium and phosphorus levels, causing weak bones, bone pain, and an increased risk of fractures (renal osteodystrophy).

• Nervous system (Brain & Nerves): The balance of salts and minerals is essential for nerves to function properly. Impaired kidney function can lead to nerve damage (neuropathy) and symptoms like muscle cramps due to electrolyte imbalances.

  • The buildup of toxins and waste products in the blood (uremia) can affect the brain and nerves, leading to difficulty concentrating, memory problems, confusion, personality changes, nerve damage (neuropathy) in the limbs, muscle twitches, cramps, and sleep problems.

• Respiratory system: Fluid retention from kidney failure can cause fluid buildup in the lungs, making it difficult to breathe. Anemia can also cause shortness of breath.

• Metabolism: The kidneys help regulate the body's overall chemistry, including the balance of water and other chemicals. They also play a role in managing acid-base balance (pH balance). 

• Integumentary System (Skin): Mineral imbalances and toxin buildup often cause persistent dry and itchy skin.

• Digestive System: High levels of urea in the blood can cause nausea, vomiting, a metallic or bad taste in the mouth, and loss of appetite.

• Immune System: The excess toxins accumulating in the bloodstream and overall bodily stress can suppress the immune system, making a person more susceptible to infections. 

Symptoms of poor kidney health

• Fluid retention causing swelling in hands and feet or puffiness around the eyes

• Fatigue

• Shortness of breath

• Nausea, vomiting, or loss of appetite

• Muscle cramps

• Itching

• Changes in urination, such as blood in the urine 

Maintaining Kidney Health 

Early kidney disease often has no symptoms. Regular check-ups, especially for those with risk factors like diabetes or high blood pressure, are crucial for early detection. 

Key steps for healthy kidneys include:

• Managing underlying conditions like diabetes and high blood pressure.

• Maintaining a healthy weight and staying physically active.

• Following a kidney-healthy diet, potentially with a renal dietitian's guidance, and reducing sodium intake.

• Quitting smoking.

• Managing stress and getting enough sleep. 

Preventive diets for kidney health focus on a heart-healthy, balanced eating pattern to manage blood pressure and blood sugar, while diets for those with existing symptoms of kidney failure require specific restrictions on protein, sodium, potassium, and phosphorus to reduce the kidneys' workload and slow further damage. 

Kidney Health Preventive Diets

A kidney-healthy diet is generally the same as a heart-healthy, balanced diet, such as the DASH (Dietary Approaches to Stop Hypertension) eating plan. The goal is to manage underlying conditions like high blood pressure and diabetes that can lead to kidney disease. 

• Sodium (Salt): Aim for less than 2,300 milligrams (mg) of sodium per day. Use herbs and spices for flavor instead of salt, and limit processed, packaged, and fast foods which are often high in sodium.

• Fruits and Vegetables: Eat plenty of fresh fruits and vegetables (aim for at least 5 portions a day). These provide essential fiber, vitamins, and minerals.

• Whole Grains: Choose whole grains like whole-wheat bread, brown rice, oats, and whole-grain pasta which offer more fiber and nutrients.

• Lean Protein: Include lean protein sources such as fish, poultry, beans, and pulses in moderate amounts.

• Healthy Fats: Use healthy, unsaturated fats like olive oil and avocado oil, and limit saturated and trans fats found in red meat and fried foods.

• Hydration: Drink enough water throughout the day, as advised by a healthcare provider.

• Alcohol: If you drink alcohol, do so in moderation (one drink per day for women, two for men). 

Diet Plans for People with Symptoms of Kidney Failure (Chronic Kidney Disease)

If you have reduced kidney function, you must work with your healthcare provider or a registered dietitian who specializes in kidney disease to create a personalized eating plan, as your nutritional needs and restrictions will depend on your specific condition and lab results. The primary goal is to minimize the buildup of waste products and manage fluid and mineral balances. 

Key adjustments may include:

• Limited Protein: You may need to limit the amount of protein you eat to reduce the workload on your kidneys. Your dietitian will determine the right amount for you, often emphasizing plant-based proteins which produce less acid than animal proteins.

• Reduced Sodium: A lower sodium target is typically recommended (often less than 2,300 mg daily, or even lower if you have high blood pressure or swelling), achieved by avoiding processed foods and not adding salt.

• Potassium Management: Damaged kidneys may struggle to remove excess potassium. You might need to limit high-potassium foods such as:

  • Avocados, bananas, melons, oranges, prunes, and raisins.

  • Potatoes, tomatoes, spinach, and beans.

  • Lower-potassium alternatives: Apples, cranberries, grapes, pineapples, cauliflower, onions, peppers, radishes, and white rice.

• Phosphorus Restriction: Phosphorus can build up and weaken bones. You may need to limit high-phosphorus foods like:

  • Whole-grain bread, bran cereals, and oatmeal.

  • Nuts, sunflower seeds, and dark-colored colas.

  • Dairy products and processed foods with phosphate additives.

  • Lower-phosphorus alternatives: Italian or sourdough bread, corn or rice cereals, unsalted popcorn, and some light-colored sodas.

• Fluid Management: Your healthcare team may advise you to limit fluid intake to avoid fluid overload, which can cause swelling and high blood pressure. 

Consult a healthcare professional for personalized medical nutrition therapy.