Q: How can I keep my kidneys healthy? Should I drink more water for my kidneys to function better?
A: Over 37 million people — more than 1 in 7 — in the United States have chronic kidney disease (CKD). What is concerning is that 9 out of 10 individuals do not know that they have CKD.
To keep your kidneys healthy, it is important to first understand the causes and risk factors associated with kidney disease.
Our kidneys perform many crucial tasks in our body. As Homer Smith, a physiologist and science writer, famously said, “The kidney is the organ par excellence of evolution.”
They continually filter the blood that traverses through them of waste products and acid that are generated from various chemical reactions in the body.
They maintain appropriate blood levels of electrolytes such as sodium, potassium, calcium, magnesium and phosphorus through absorption and excretion via subunits called nephrons. The preservation of these electrolyte levels is needed for optimal functioning of multiple vital organs such as the heart, brain and muscles.
The kidneys manage blood pressure through regulation of salt and water and production of hormones.
The kidneys also secrete hormones that are responsible for conservation of bone health and continual production of red blood cells (the oxygen-carrying component of the blood).
When the kidneys fail to perform these tasks, many other organs and our overall health are impacted. CKD is recognized as one of the leading causes of death worldwide. And thus, earlier detection, mitigation, and treatment of modifiable causes and risk factors of CKD is important.
Symptoms associated with CKD — such as nausea, vomiting, weight loss, reduced appetite and generalized malaise — frequently manifest when the disease is in its advanced stages. And so, it is even more pertinent to undergo screening tests if you have any risk factors associated with CKD.
Elevated blood pressure (hypertension) and diabetes are the foremost causes of CKD. And heart disease, obesity, cigarette smoking, ethnicity (African Americans and Hispanics have a higher risk of developing CKD), family history of CKD and abnormal kidney system anatomy are the main risk factors.
If you have any of these conditions or risk factors, your doctor should periodically monitor blood and urine laboratory indexes that could detect onset of CKD. These tests include a glomerular filtration rate (a measure of how well your kidneys are working) and urine albumin (an early marker of kidney disease).
Use of certain over-the-counter medications, such as nonsteroidal anti-inflammatory drugs, including ibuprofen, naproxen and diclofenac, and proton pump inhibitors, including pantoprazole and omeprazole, is associated with a risk of developing CKD. If you are using these drugs on a regular basis — which differs from person to person — you should discuss it with your doctor, especially if you have any risk factors for CKD.
Since many cases of hypertension and diabetes arise from certain dietary choices, including salt intake, and weight gain, making healthier choices can have a downstream effect of reducing your risk of developing CKD.
A diet high in fruits, vegetables and low-fat dairy products (the DASH diet) has been shown to have a considerable effect in reducing blood pressure. This diet combined with salt reduction lowers the risk of hypertension, Type 2 diabetes, cardiovascular disease, stroke and mortality.
Research at Johns Hopkins University that followed over 15,000 adults for 20 years, has demonstrated that the DASH diet could reduce the risk of developing kidney disease. This study also found that individuals with a high intake of red and processed meats had a higher risk of developing CKD.
A plant-based or vegan diet has also been shown to prevent kidney disease and slow its progression.
Since exercise is beneficial in mitigating various causes and risk factors, such as hypertension, diabetes and cardiovascular disease, associated with kidney disease, its effects have been studied in the large-scale National Health and Nutrition Examination Survey (NHANES). Individuals with higher levels of physical activity measured by an accelerometer and a questionnaire were more likely to have healthier kidney function.
The National Kidney Foundation recommends that people with CKD exercise at least three nonconsecutive days a week, building up to 30 minutes per session.
As nephrologists, we are frequently asked if increasing water intake, beyond general recommendations, has an effect on improving kidney function.
A study that examined water intake in patients with CKD showed that increasing water consumption by over 1 liter (about 34 fluid ounces) per day did not reduce progression of kidney disease. There is also no robust evidence to suggest that increased water intake prevents CKD.
Increased fluid intake, however, is associated with reduction in the formation of kidney stones. Frequently developing kidney stones may increase the risk of kidney disease.
The National Academy of Medicine suggests a fluid intake of nearly 100 ounces per day in men and 70 ounces per day in women (this being a guide for intake rather than a daily goal). Increased physical activity and exposure to warmer temperatures warrants an increase in this recommended amount, while patients with certain medical conditions and lower weights should lower consumption.
There is no one size that fits all for water consumption, but the general recommendation is simple — drink to thirst with regulation based on activity and climate.
Meet the doctors: Sam Kant is a general and transplant nephrologist, and an assistant professor of medicine at the Division of Nephrology and Comprehensive Transplant Center at Johns Hopkins University School of Medicine.
Natasha Dave is a nephrologist and medical director at Strive Health.
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