Amino Acid
Protein
Also known as: whey protein, plant protein, barley protein, rice protein
Protein is a macronutrient composed of amino acids essential for building and repairing muscle tissue, supporting immune function, and maintaining overall body composition. It is obtained through diet or supplementation and is critical for athletes, active individuals, and general health maintenance.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every Protein product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Thorne Protein Isolate - Chocolate | 96 A | $1.47 |
| 2 | Thorne Whey Protein Isolate - Vanilla | 96 A | $1.47 |
| 3 | NutraBio Clear Whey Protein Isolate Powder | 96 A | $2.15 |
| 4 | NutraBio Whey Protein Isolate Powder | 96 A | $2.50 |
| 5 | Transparent Labs Grass-Fed Whey Protein Isolate | 95 A | $2.00 |
| 6 | Transparent Labs Grass-Fed Beef Protein Isolate | 89 A | $2.00 |
| 7 | Onnit Grass Fed Whey Isolate Protein - Vanilla (30 Serving Tub) | 89 A | $2.00 |
| 8 | Thorne MediClear-SGS™ - Vanilla | 86 A- | $2.10 |
| 9 | Thorne RecoveryPro® | 85 A- | $3.67 |
| 10 | Nutricost Whey Protein Concentrate Powder | 85 A- | $2.65 |
| 11 | Nutricost Casein Protein Powder | 84 A- | $1.53 |
| 12 | Nutricost Grass-Fed Whey Protein Concentrate Powder | 84 A- | $2.42 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much Protein should I take?
The typical range is 20-40 g per serving, 1-3 servings daily. Can be used long-term as part of regular supplementation
When should I take Protein?
Post-workout timing is most effective; can be consumed throughout the day. Can be taken with or without food; post-workout absorption may be enhanced with carbohydrates.
Which form of Protein is best?
whey protein concentrate. Other forms in the catalog: whey protein isolate, plant-based blends, barley protein, rice protein.
Is Protein safe?
Commonly reported: Bloating or gas (particularly with plant-based proteins), Digestive discomfort in sensitive individuals, Occasional constipation.
Which Protein supplement scores highest?
Thorne Protein Isolate - Chocolate, at 96/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Daily target & upper limit
50 g / dayProtein has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
Protein dosage reference →Primary uses
- Muscle building and recovery
- Post-workout recovery
- Muscle maintenance
- Satiety and weight management
- General nutritional support
What systematic reviews concluded
Outcomes that systematic reviews of Protein reached a verdict on: 5 with a benefit, 1 with harm reported, 2 unclear. Each is quoted from a review and linked to it on PubMed. How these were read.
Reviews found a benefit (5)
“whey protein significantly improved bench press (mean difference [MD] 8.87; 95% CI: 5.95-11.79) and squat performance (MD 9.60; 95% CI: 5.61-13.60), with low to no heterogeneity.” PMID 41454445 · 4 reviews
“additionally, whey plus multicomponent exercise training achieved the most promising effects on such sarcopenia-related physical indicators such as chair rise (large effect, SMD = 1.09; CoE: high), timed up and go (medium SMD, 0.70; CoE, high), and global mobility score (large SMD, 1.02; CoE, high).” PMID 42124009 · 2 reviews
“The combination of whey protein supplementation and exercise improves MPS in a time- and dose-dependent manner.” PMID 40871607
“In comparison to the placebo group, whey protein supplementation enhanced the phosphorylation levels of AKT, mTOR, eukaryotic translation initiation factor 4E-binding protein-1 (4E-BP1), 70 kDa ribosomal protein S6 kinase (p70S6K), and ribosomal protein S6 (rpS6) at 1-2 h post-exercise.” PMID 40871607
“WP supplementation during RET is more effective in increasing handgrip strength and skeletal muscle mass in older people with Sarcopenia compared with RET with or without placebo supplementation.” PMID 37571361
Harm reported (1)
“The majority of the papers associated the damaging effect with the chronic and abusive use of whey protein, with the kidneys and liver being the main organs affected.” PMID 32702243
Not enough to say: muscle mass; fat-free mass in obesity.
How it works
- Provides amino acids for muscle protein synthesis
- Stimulates mTOR pathway for anabolic signaling
- Supports enzyme and hormone production
- Enhances satiety through metabolic effects
Dosage
- Typical range
- 20-40 g per serving, 1-3 servings daily
- Timing
- Post-workout timing is most effective; can be consumed throughout the day
- With food
- Can be taken with or without food; post-workout absorption may be enhanced with carbohydrates
- Duration
- Can be used long-term as part of regular supplementation
- Special populations
- Requirements increase with age (65+ may need 1.2-1.6 g/kg body weight); individualize based on activity level and training goals
Forms
- whey protein concentrate· 70/100
- whey protein isolate· 70/100
- plant-based blends· 70/100
- barley protein· 70/100
- rice protein· 70/100
Safety
Common side effects
- Bloating or gas (particularly with plant-based proteins)
- Digestive discomfort in sensitive individuals
- Occasional constipation
Contraindications
- Milk allergies (for whey/casein sources)
- Severe kidney disease (consult healthcare provider)
- Phenylketonuria (PKU) if containing phenylalanine
Products containing Protein
Top-scoring supplements in our catalog that list Protein on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Evidence notes
Extensive RCT evidence demonstrates protein supplementation significantly supports muscle growth and recovery, particularly when combined with resistance training. Well-established macronutrient with decades of research.
Grade A: Multiple well-designed human trials support the main claims.
Cited research for Protein
Clinical studies referenced across Formulate guides that mention protein. Each links to the full study page with PubMed source + the guides that cite it.
Related in Amino Acid
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.