Losing Weight, Cutting Phosphorus May Halt CKD

Encourage patients to avoid high-fat foods.
Encourage patients to avoid high-fat foods.

Reductions in waist circumference and 24-hour urine phosphorus excretion may prevent chronic kidney disease (CKD) or slow its progression, according to study findings published in the American Journal of Kidney Diseases (2013;62:900-907).

A team led by Alex Chang, MD, MS, of the Division of Nephrology and the Welch Center for Prevention, Epidemiology, and Clinical Research at Johns Hopkins University in Baltimore studied urinary albumin excretion (UAE) in 481 patients with normal kidney function who had participated in the PREMIER blood pressure–lowering trial. That study focused on weight loss, healthful diet, and exercise among mostly overweight or obese individuals with prehypertension or stage I hypertension.

For their observational analysis of the PREMIER participants, Dr. Chang and his colleagues examined 24-hour urine specimens collected at baseline and at six months. The researchers found that after six months, the proportion of subjects with UAE of 10 mg/day or more fell from 18.7% to 12.7%. Mean waist circumference decreased by 4.2 cm, mean 24-hour excretion of sodium dropped by 28.2 mmol/day, mean potassium increased by 8.4 mmol/day, mean phosphorus decreased by 27.7 mg/day, and mean protein intake was reduced by 1.7 g/day.

After adjustment for relevant covariates, the investigators found that decreases in waist circumference, 24-hour urine phosphorus excretion, and protein intake were significantly associated with UAE reduction in separate models. Ultimately, the first two factors, but not protein intake, remained significantly associated with UAE reduction, even after adjusting for changes in blood pressure and insulin resistance. In addition, participants with higher UAE and baseline metabolic syndrome experienced greater reductions in UAE from decreases in waist circumference.

“Other studies have suggested that once [a person is] diagnosed with kidney disease, weight loss may slow kidney disease progression, but this is the first research study to support losing belly fat and limiting phosphorus consumption as a possible way to prevent kidney disease from developing,” noted Joseph Vassalotti, MD, Chief Medical Officer of the National Kidney Foundation.

He added, “A good rule of thumb is that if the food comes in a package, it's likely to be high in phosphorus. This study suggests limiting the amount of processed foods in [the] diet may be an easy way to reduce [the] risk of developing kidney disease.”

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