Does plant protein help with liver or kidney health? What the research does and doesn't show

The evidence doesn't support plant protein as a treatment for liver or kidney disease — but the research on protein source and kidney health points a specific direction worth knowing: reviews on preventing kidney stones and preserving kidney function generally recommend shifting toward plant protein and limiting animal protein, not the other way around.

What the evidence doesn't support

It doesn't support plant protein, in any amount or form, as a treatment for liver disease, chronic kidney disease (CKD), or kidney stones once they've formed. It also doesn't support higher-protein diets generally as harmful to healthy kidneys — the concern some people have about protein and kidney damage is based on the wrong population. Nothing here is medical advice for someone with a kidney or liver diagnosis; that's a conversation for a nephrologist, hepatologist or dietitian who knows the specifics.

What the trials found

Kidney stones and CKD. A 2023 review of kidney stone prevention strategies recommended, for people who form calcium or uric acid stones, limiting animal protein to 0.8-1.0 g/kg body weight per day and increasing the proportion of plant protein in the diet, alongside other measures like fluid intake and limiting sodium and oxalate-rich foods. This is dietary guidance based on the mechanism (animal protein raises urinary calcium and uric acid more than plant protein does), not a controlled trial that gave people plant protein and measured new stone formation.

A 10-year cohort study of 1,374 older women found that eating more plant-sourced protein was associated with a slower decline in kidney function (eGFR) over time — each additional 10 g of plant protein a day was linked to about 0.12 mL/min/1.73m² less yearly decline — while animal protein intake showed no association either way. The plant protein measured here came mostly from fruits, vegetables and nuts via a food questionnaire, not an isolated protein powder, and this is an association in observational data, not a trial proving cause and effect.

Separately, a meta-analysis of 28 randomized trials in 1,358 healthy adults without kidney disease found higher-protein diets (≥1.5 g/kg/day or ≥100 g/day), regardless of source, did not worsen the change in kidney function compared with normal- or lower-protein diets — evidence against the idea that a higher-protein diet damages healthy kidneys.

Liver. A 2021 meta-analysis of 5 randomized trials tested a soy-based diet against a control diet in people already diagnosed with nonalcoholic fatty liver disease (NAFLD). The soy diet reduced insulin resistance (HOMA-IR) and a marker of oxidative stress (malondialdehyde), but showed no significant effect on liver enzymes (ALT, AST), BMI, total cholesterol or LDL — the markers most directly tied to liver injury and overall metabolic improvement didn't move. This is soy-based dietary intake in a NAFLD population, not our fava bean and fermented yeast protein blend, and it's a mixed result even on its own terms.

Questions people ask

Can plant protein cause kidney stones?

The evidence points the other way. Kidney stone prevention guidance recommends increasing plant protein and limiting animal protein for people who form calcium or uric acid stones, based on how each affects urinary calcium and uric acid. No trial has tested plant protein powder specifically for causing or preventing stones.

What plant protein is good for kidney disease?

This isn't a question this page can answer safely. Protein needs in CKD are highly individualized — they depend on the stage of kidney disease and whether someone is on dialysis — and are set by a nephrologist or renal dietitian, not a general plant-protein guide. The observational and trial evidence above describes people without diagnosed kidney disease.

Is plant protein powder bad for kidney stones?

The available evidence doesn't support that. If anything, the dietary guidance for people prone to calcium and uric acid stones favors plant protein over animal protein. That guidance is about dietary pattern, not a specific plant protein supplement.

Does plant protein help with liver disease?

The one meta-analysis on this, in people already diagnosed with fatty liver disease, found soy-based intake improved insulin resistance but had no significant effect on liver enzymes or cholesterol. That's a mixed result for soy specifically, and it doesn't test our fava bean and fermented yeast protein blend.

When to talk to a doctor

Kidney disease, liver disease, or a history of kidney stones need individualized dietary guidance from a doctor, nephrologist, hepatologist or renal dietitian — protein targets in these conditions vary by diagnosis and stage, and general guidance like this page can't substitute for that. Plant protein is not a treatment for kidney or liver disease. If you take medication for either, or are pregnant or nursing, talk to a doctor before adding any supplement.

Related reading: who should not take plant protein, plant protein side effects, and plant protein: what the research shows.