News: Strict protein restriction in chronic kidney disease associated with worse clinical outcomes, study finds

Consuming less than 0.6 g/kg of protein a day correlated with higher risks of kidney failure and death, according to a recent study published in JAMA Network. Compared with patients consuming the highest amount of daily protein, those consuming the least had a 42% greater risk of kidney failure requiring long-term maintenance hemodialysis, peritoneal dialysis, or kidney transplantation.

In terms of secondary endpoints, the lowest protein intake category was associated with more than double the risk of all-cause mortality, though was not linked to more adverse cardiovascular events.

The biological rationale for protein restriction “is centered on the premise that protein intake serves as a primary source of uremic toxins and metabolic acidosis, which together drive intraglomerular hypertension and accelerate the progression of kidney injury,” the researchers explained.

For the KNOW-CKD study, investigators analyzed 1,861 patients with CKD stages 1 to predialysis 5 across nine tertiary hospitals from 2011 to 2016, following them for a median of 9.3 years. Daily protein intake was objectively estimated using baseline 24-hour urinary urea nitrogen excretion.

Participants in the lowest daily protein intake category tended to have higher body mass index and systolic blood pressure, alongside lower baseline serum albumin, hemoglobin, and estimated glomerular filtration rates. Diabetes was also more prevalent in this group.

The link between severe protein restriction and kidney failure requiring replacement therapy held across sensitivity analyses, such as excluding patients reaching that stage with 1 year of those with protein-energy wasting markers and adjusting for echocardiographic parameters.

The findings “provide robust longitudinal evidence to support this normalization of protein intake,” researchers wrote. The findings also suggest that risks of the traditional 0.6 g/kg per day threshold “may outweigh the marginal benefits of kidney workload reduction.”

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