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Maintaining kidney health across ages

Writer's picture: Fatima QureshiFatima Qureshi

Maintaining kidney health throughout life requires a focus on diet and lifestyle choices that support kidney function and overall well-being. The sources emphasize that the kidneys are highly vascular organs responsible for filtering blood and removing waste products. Protecting kidney function requires careful attention to dietary choices and other health-promoting behaviors.

Kidney Function and Aging

  • Kidneys act as nonstop water filters for the blood, processing up to 150 quarts of blood every 24 hours. This function is critical to overall health, and impaired kidney function can lead to a buildup of metabolic waste products in the blood, causing symptoms like weakness, shortness of breath, confusion, and abnormal heart rhythms.

  • Most people with declining kidney function don't experience any symptoms. A national survey found that only 41 percent of Americans tested had normal kidney function, a drop from 52 percent a decade earlier.

  • Approximately one in three Americans over the age of 64 may suffer from chronic kidney disease (CKD). More than half of American adults aged 30 to 64 are expected to develop chronic kidney disease during their lifetimes.

  • Kidney malfunction can be so damaging to the rest of the body that most people don’t live long enough to reach kidney failure. In a study of Americans over 64 with CKD, most died of cardiovascular disease before developing end-stage kidney failure.

  • Kidney function tends to decline with age. Kidneys may start to deteriorate in your twenties, and by the time you reach your eighties, you may be down to half capacity. As we age, the pH of our blood falls to the lower (more acidic) end of the spectrum, perhaps due in part to the declining ability of our kidneys to excrete acid.


Dietary Factors and Kidney Health

  • Animal Products: The standard American diet, which is high in animal products, can be toxic to blood vessels in the heart, brain, and kidneys. Researchers have found three specific dietary components associated with declining kidney function: animal protein, animal fat, and cholesterol. These are found only in animal products. There is no association between kidney function decline and the intake of protein or fat from plant sources.

  • Plant-Based Diets: The diets that are healthiest for our hearts—those centered around unprocessed plant foods—may be the best way to prevent and treat kidney disease as well. A plant-based diet alkalinizes the kidneys, whereas a nonvegetarian diet carries an acid load. A plant-based diet can also help to reverse the effects of kidney disease.

  • Protein: High animal protein intake can induce a state called hyperfiltration, which is a dramatic increase in the workload of the kidney. Within hours of consuming meat, kidneys go into hyperfiltration mode. Beef, chicken, and fish appear to have similar effects. However, an equivalent amount of plant protein causes virtually no noticeable stress on the kidneys. The hyperfiltration response disappears when study participants are given a powerful anti-inflammatory drug along with animal protein. A high intake of animal protein can profoundly influence normal human kidney function.

  • Acid Load: Dietary acid load is determined by the balance of acid-inducing foods (such as meats, eggs, and cheese) and base-inducing foods (such as fruits and vegetables). A higher dietary acid load was associated with a significantly higher risk of protein leakage into the urine, an indicator of kidney damage. Diets high in animal products produce acid, while plant-based diets produce base in the kidneys. The switch from base- to acid-forming diets may help explain our modern epidemic of kidney disease. To buffer the excess acid formed by your diet, kidneys produce ammonia, which can have a toxic effect over the long term. A meat-rich diet contributes to chronic, low-grade, metabolic acidosis, which helps explain why people eating plant-based diets appear to have superior kidney function.

  • Kidney Stones: When urine is more alkaline, stones are less likely to form. The standard American diet yields acidic urine. When people are placed on a plant-based diet, their urine can be alkalinized up to a near-neutral pH in less than a week. Less meat and more fruits and vegetables appear protective. Not all plant foods are alkalinizing, and not all animal foods are equally acidifying.

  • Dietary Fat: Fat in the blood can cause insulin resistance. An obese person's body may be constantly spilling fat into the bloodstream, which can cause insulin resistance.

  • Phosphate: Phosphate additives in food can be a health risk. Enhanced meat and poultry products have implications for patients receiving dialysis. Dietary phosphorus can acutely impair endothelial function.

  • Sodium: Dietary sodium loading impairs microvascular function. A high-salt meal can impair endothelial function.


Other Factors Impacting Kidney Health

  • Hydration: Older individuals may only be about 50 percent water, compared to 70 percent for newborns. With smaller fluid reserves, a diminished sensation of thirst, and the waning ability of the kidneys to concentrate urine, the elderly are particularly susceptible to dehydration. Dehydrated individuals are at increased risk for heart attacks, pneumonia, and blood clots, which results in a doubling of the odds of becoming disabled over the subsequent four years. Urine color is not a reliable indicator of hydration status in adults older than sixty-five.

  • Blood Vessels: A recent editorial in the journal Aging Medicine rhapsodized that “the blood vessel is the candle of life,” asserting that “[a]ll disease stems from vessels”. The loss of blood vessel density may contribute to organ deterioration as we age. The capacity of blood vessels to repair themselves is dependent on endothelial progenitor cells that emerge from stem cells in our bone marrow.

  • Inflammation: Animal fat and animal protein can be inflammatory. A proinflammatory diet is associated with reduced kidney function in elderly adults.


Strategies for Maintaining Kidney Health Across Ages

  • Adopt a Plant-Based Diet: Emphasize whole, unprocessed plant foods to reduce the intake of animal protein, animal fat, and cholesterol. This approach can help to reduce the workload on the kidneys, prevent hyperfiltration, and reduce acid load.

  • Limit Animal Protein: Reduce the consumption of meat, poultry, and fish to minimize stress on the kidneys.

  • Stay Hydrated: Be mindful of fluid intake, especially in older adults, who may have a diminished sense of thirst. Though urine color is not a reliable indicator for those over 65, fatigue and missing drinks between meals may be predictive of impending dehydration.

  • Minimize Processed Foods: Limit consumption of processed foods that are high in sodium, phosphate additives, and other potentially harmful substances.

  • Engage in Regular Exercise: Aerobic exercise is a first-line strategy for helping to prevent and treat arterial aging.

  • Avoid Smoking: Exposure to even secondhand cigarette smoke can harm blood vessels.

  • Maintain Healthy Blood Pressure: Monitor blood pressure and take steps to manage it through diet and lifestyle changes if necessary.

  • Monitor Kidney Health: Regularly check kidney function, especially for those with risk factors for kidney disease.


By adopting these strategies, individuals of all ages can support their kidney health and reduce the risk of kidney disease. The sources emphasize that diet plays a key role in both preventing and treating kidney issues.


References 

  • Greger, M., & Stone, G. (2015). How not to die: Discover the foods scientifically proven to prevent and reverse disease. Flatiron Books.

  • Greger, M. (2023). How not to age: The scientific approach to getting healthier as you get older. Flatiron Books.


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