A warning repeated in every gym and gathering. Because it concerns vital organs, it deserves careful examination — neither a quick dismissal nor scaremongering.
What does the evidence say about healthy people?
A randomised crossover study of 44 healthy resistance-training volunteers showed that a high-protein diet (over 3 grams/kg per day) for six months produced no adverse effects on kidney function[1]. Controlled studies through 2024–2025 show no clinically meaningful declines in kidney function in people without pre-existing kidney disease[1].
A formal scientific discussion was also published describing claims of adverse effects of whey supplementation on human kidney and liver function as unsubstantiated[2].
effect on healthy kidneys
describes harm claims
— medical supervision only
But the exception matters greatly
People with existing kidney disease should not take concentrated protein except under medical supervision, since excess protein may strain already weakened kidneys[1]. The same applies to those with dairy allergy or severe lactose intolerance[1].
And is whey even necessary?
No. It is a convenient vehicle for reaching your protein target, not a magic substance. A systematic review and meta-analysis in older adults found effects of whey supplementation on body composition, muscle strength and cardiometabolic health[3] — but meat, eggs, lentils and laban serve the same purpose, usually at lower cost (our local sources).
Practical rules
- Food first, supplements to close the gap — not the reverse.
- Drink enough water alongside high protein.
- Test if unsure: a simple creatinine test provides reassurance.
- Beware "blends": some unregulated products contain undeclared additives — buy from trusted, registered sources.