Protein Powder
The evidence that protein supplementation supports muscle gain with resistance training is among the most robust in nutrition science: a 2018 meta-analysis of 49 trials (PMID 28698222) confirmed the benefit with a ceiling at roughly 1.6 g/kg/day. Heavy-metal contamination in protein powders is a legitimate concern documented across multiple independent investigations, with plant-based proteins consistently showing higher levels than whey; the widely cited 'nearly half exceed safety thresholds' headline is based on California Prop 65 limits (a threshold approximately 25x stricter than the FDA adult reference level) and the Clean Label Project methodology has been formally disputed by CRN and NPA as non-peer-reviewed and without full transparency. Consumers who prioritize both efficacy and safety are best served by NSF Certified for Sport or Informed Protein-certified products.
Generally well tolerated in healthy adults. In people with normal kidney function, high protein intakes up to at least 2.2 g/kg/day are not associated with kidney damage; individuals with pre-existing kidney disease (particularly CKD with eGFR below 30) should consult a clinician before significantly increasing protein intake. Plant-based protein powders absorb more naturally occurring heavy metals (lead, cadmium, arsenic) from soil than whey derived from milk; consumers using plant-based protein daily at multiple servings should prioritize third-party-tested brands. Not a treatment for any disease.
Full safety details belowEvidence by use
Each use graded independently. A strong grade for one use does not carry over to others.
Strong, consistent human trials.
Moderate evidence; some gaps remain.
Moderate evidence; some gaps remain.
Generally well tolerated in healthy adults. In people with normal kidney function, high protein intakes up to at least 2.2 g/kg/day are not associated with kidney damage; individuals with pre-existing kidney disease (particularly CKD with eGFR below 30) should consult a clinician before significantly increasing protein intake. Plant-based protein powders absorb more naturally occurring heavy metals (lead, cadmium, arsenic) from soil than whey derived from milk; consumers using plant-based protein daily at multiple servings should prioritize third-party-tested brands. Not a treatment for any disease.
Who takes it and why
Each expert's dose and stated reason, linked to their own words. Attribution only; no endorsement implied.
Photo: Jop van Velthuis, CC BY-SA 4.0, via Wikimedia Commons ↗Building and maintaining muscle is critical for longevity and metabolic health; skeletal muscle is the primary site of glucose disposal and muscle loss accelerates frailty, cardiovascular risk, and cognitive decline; the RDA (0.8 g/kg) was derived from nitrogen balance studies in young sedentary men and fails older adults and exercisers
peterattiamd.com ↗Attribution only; no endorsement implied.
RDA (0.8 g/kg) prevents deficiency but does not optimize muscle health; cites stable isotope studies supporting 1.2-1.6 g/kg as practical optimum; for active adults in resistance training, 1.6 g/kg has been shown to maximize lean mass gains; older adults may need the higher end to prevent frailty
www.foundmyfitness.com ↗Attribution only; no endorsement implied.
Photo: M Robertson, CC BY 4.0, via Wikimedia Commons ↗Protein is a foundational longevity nutrient for muscle repair and preservation; Blueprint frames muscle retention as anti-aging infrastructure; luteal-phase elevation compensates for progesterone-driven muscle catabolism
blueprint.bryanjohnson.com ↗Attribution only; no endorsement implied.
Which Protein Powder should you buy?
The short version: plain protein powder is the most-studied and least-expensive form, and any product that is third-party certified is a safe bet. Certification (NSF Certified for Sport or USP Verified) screens for banned substances and confirms the label matches what is in the bottle. Here are recognizable brands that carry it. We do not certify products and take no payment to list them.
134 Protein Powder products are third-party certified in total. See the full list →
Published lab tests on Protein Powder
These studies test the ingredient category, not a single branded product. All attributed to their original source. We do not run the tests.
47% of tested protein products exceeded California Prop 65 or other federal safety thresholds for at least one contaminant; 21% exceeded Prop 65 lead limits by 2x or more; plant-based protein powders showed 77% exceedance. Note: Prop 65 lead MADL is 0.5 mcg/day, roughly 25x stricter than the FDA adult reference level of 12.5 mcg/day; methodology disputed by CRN and NPA as non-peer-reviewed.
All 15 products contained detectable levels of at least one heavy metal; three products (EAS Myoplex Original Rich Dark Chocolate, Muscle Milk Chocolate, Muscle Milk Vanilla Creme) exceeded proposed daily safety limits at 3 servings/day.
Sources
- A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults (2018) review
- The effects of consuming frequent, higher protein meals on appetite and satiety during weight loss in overweight/obese men (2011) rct
- Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group (2013) review