How much plant protein is too much?

There's no official number that marks "too much" protein the way there is for, say, vitamin A. The closest research points are a large meta-regression that found no added muscle benefit past roughly 1.62 g/kg of body weight a day, and a separate review that found higher-protein diets didn't worsen kidney function in people who started with healthy kidneys. Neither is a safety ceiling; both are about where the benefit runs out.

There's no tolerable upper limit set for protein

The NIH Office of Dietary Supplements lists a Recommended Dietary Allowance for protein (0.8 g/kg/day for a sedentary adult) but no Tolerable Upper Intake Level, unlike vitamins A, D or minerals such as zinc and selenium, which do have a defined UL. That's not an oversight — it reflects that healthy adults tolerate a fairly wide range of protein intake, and the research hasn't identified one clear ceiling where harm reliably starts.

The clearest ceiling in the research is about benefit, not harm

A 2018 systematic review, meta-analysis and meta-regression of 49 randomized trials (1,863 adults) tested protein supplementation alongside resistance training. It found added protein improved strength and lean mass up to a point — but once someone's total daily protein (food plus supplement) passed about 1.62 g/kg of body weight, more protein didn't produce more benefit. That's a plateau in what protein does for muscle, not evidence that going higher causes harm; the trial simply didn't find extra upside past that point.

What the kidney research says about pushing intake higher

A 2018 systematic review and meta-analysis of 28 randomized controlled trials (1,358 participants) compared higher-protein diets (≥1.5 g/kg/day, or ≥20% of energy, or ≥100 g/day) against normal- or lower-protein diets, tracking kidney function (GFR) in adults. The post-intervention GFR was slightly higher in the high-protein groups, but the change in GFR over the trial didn't differ between higher- and lower-protein diets. The authors concluded higher protein intake didn't adversely affect kidney function — in people who had normal kidney function to begin with. That trial doesn't cover anyone with existing kidney disease, where protein clearance already works differently; see who should not take plant protein for that caution.

What "non-toxic" searches are usually really asking

Some people searching "how much plant protein is too much" are really asking about contaminants — heavy metals, in particular — rather than the protein itself. That's a separate question with separate research behind it; see third-party testing for plant protein: what the seals mean for what testing does and doesn't cover, and for where our own label stands (we hold no third-party certification for this product).

Where our label draws the line

Our label directs one two-scoop serving (21 g of protein) daily and states "do not exceed recommended dose," without spelling out what a higher amount would do. We have no data — ours or anyone else's — testing this specific fava bean and yeast blend at two or three times that serving, so we can't tell you what happens at a multiple of the label dose beyond the general research above.

Questions people ask

What happens if you take too much plant protein powder?

The most commonly reported issue with protein powders generally is digestive — bloating, gas or looser stools, especially with a sudden increase — covered in does plant protein cause diarrhea, bloating or constipation?. No dedicated dose-response trial for this blend exists, so we can't give you numbers for our product specifically.

Is there a toxic dose of plant protein?

No established toxic dose has been defined for dietary protein in a healthy adult, and no health authority sets a tolerable upper limit for it. The research above addresses where added benefit stops (around 1.62 g/kg/day of total protein), which is a different question from toxicity.

Can too much protein hurt your kidneys?

Not according to the trial evidence in people with normal kidney function to start — the 2018 meta-analysis above found no adverse change in kidney function at higher intakes in that population. That finding doesn't extend to anyone who already has kidney disease, who should ask a doctor before increasing protein intake of any kind.

How much plant protein per day is safe long-term?

Long-term dose-finding data for this specific blend doesn't exist. General protein-safety research in healthy adults, covered above and in is it safe to take plant protein every day?, is the closest available evidence.

Related reading: how much plant protein should you take a day, is it safe to take plant protein every day?, and who should not take plant protein.