Dr. Alex Chang, MD, MS, Johns Hopkins University Nephrology Fellow
A common memory for me growing up was my mother constantly handing me plates of apples, oranges, and grapes after dinner. As I’ve gotten older, I realize I should’ve been listening more to my mother’s advice! Many research studies have shown beneficial effects of consuming more fruits and vegetables and less meat. A diet filled with fruit and vegetables has been shown to lower blood pressure. However, those with kidney disease have complicated dietary needs and restrictions.
One particular concern is the decreased ability to rid the body of excessive dietary acid loads as well as potassium. Since the Western diet is typically heavy in acid-producing animal protein and low in base-producing vegetable protein, it’s possible that changing dietary habits may be beneficial in acid-base balance.
An interesting study was published in the Clinical Journal of the American Society of Nephrology with the goal of determining whether increasing fruit and vegetable intake could improve acid levels for carefully selected individuals with chronic kidney disease. Individuals were considered for this study if they had kidney disease due to high blood pressure, high acid levels, and could not afford the medication commonly used to improve acid levels. They had their blood pressure carefully controlled, and their potassium levels were carefully checked to make sure eating fruits and vegetables would not cause problems with high potassium levels, which can be dangerous for kidney disease patients. Participants were then randomly assigned to receive either medication or fruits and vegetables free of charge. The medication provided was sodium bicarbonate, which is commonly used to lower acid levels in the blood. Fruits and vegetables that were provided included apples, apricots, oranges, peaches, pears, raisins, strawberries, carrots, cauliflower, eggplants, lettuce, potatoes, spinach, tomatoes, and zucchini.
Interestingly, this study found that one year of fruits and vegetables or sodium bicarbonate improved acid levels for both groups. Blood pressure decreased significantly in the fruits and vegetables group after one year, which is consistent with other studies that have shown this effect. However, acid levels improved more in the sodium bicarbonate group than the fruits and vegetable group in this study.
This study is definitely intriguing and suggests the possibility that making substantial dietary changes could improve acid levels in people with kidney disease. However, larger studies need to be done to see if this approach can be effective in safely reducing acid levels in patients with chronic kidney disease.
For those of you with kidney disease, it’s important to remember that diet does matter. It can have the same impact as starting a new medication. While changing our lifestyle behaviors and particularly dietary habits is very difficult to do, making these changes could have a big impact on our health. Of course, many people with kidney disease have special dietary considerations so before embarking on major dietary changes always consult with your nephrologist or renal dietician.