Does whey protein affect kidney health? What the research does and doesn't show

The evidence doesn't support whey protein causing kidney stones or damaging kidneys in people with healthy kidneys. The one trial testing whey protein's effect on stone-forming risk factors found no significant average change over three days — though individual results varied enough that people who already form stones should be cautious rather than assume the average finding applies to them.

What the evidence doesn't support

It doesn't support whey protein causing kidney stones in a general, healthy population — the average result in the one dedicated trial was no change in the urinary measures tied to stone risk. It doesn't establish that whey protein is safe for people who already have kidney disease or a history of kidney stones, since neither group was the one tested. And it doesn't tell us anything about long-term daily use, since the only dedicated trial ran three days — not months or years.

What the trials found

A 2017 trial gave 18 healthy volunteers either whey protein or albumin supplements, one scoop a day, for three days each, with a week's washout between the two and a controlled baseline diet. Averaged across all 18 participants, urinary calcium, phosphorus, sodium, potassium, uric acid, citrate, oxalate, magnesium, creatinine, pH and calculated stone-risk indices did not differ significantly from before supplementation. But individually, results varied more than the average suggests: 39% of participants had an increase of more than 50% in urinary calcium, and 44-67% (depending on which supplement) had a decrease in urinary pH — more acidic urine is itself a stone-risk factor. The authors concluded the average findings were reassuring but recommended closer monitoring specifically for people who already form stones.

On kidney function more broadly, a 2018 systematic review and meta-analysis of 28 randomized trials (1,358 people) compared higher-protein diets against normal or lower-protein diets in adults without kidney disease and found no worsening in the change in kidney function (GFR). A separate 30-day trial in 40 healthy, resistance-trained men taking about 80 g/day of whey protein — over three times our 22 g serving — found no adverse change in kidney, liver or metabolic markers. That's the extent of the liver-specific safety data available too: no dedicated trial has tested whey protein in people with existing liver disease.

Questions people ask

Can whey protein cause kidney stones?

The one trial testing this directly found no significant average change in the urinary measures tied to stone formation over three days in healthy volunteers, though individual results varied — some participants saw meaningfully higher urinary calcium. It wasn't tested in people who already form stones.

Does whey protein cause kidney disease, or damage kidneys?

In healthy adults, a meta-analysis of higher-protein diets found no worsening of kidney function. That finding doesn't cover people who already have kidney disease, since that population wasn't the one studied.

Is whey protein bad for people who already have kidney stones?

The stone-risk trial above specifically didn't test people with a history of stones. Given that some participants showed real increases in urinary calcium and more acidic urine, that's a reasonable question for a doctor or dietitian before adding a protein supplement if you're a known stone-former — not a reason for someone without that history to worry based on this trial.

Can whey protein damage your liver?

The 30-day trial above, in healthy resistance-trained men at roughly 80 g/day, found no adverse change in liver markers alongside kidney and metabolic ones. We didn't find a dedicated trial testing whey protein in people with existing liver disease.

When to talk to a doctor

Kidney disease, a history of kidney stones, and liver disease are all reasons to ask a doctor before adding any protein supplement. Whey protein is not a treatment for any of these conditions, and the research above hasn't shown it to be harmful in short trials of healthy people — that's a different thing from being tested and cleared for someone who already has one of these conditions.