🥇 Top Rated Product
9.8/10
The world's best-selling protein for 15 years. WPI-first blend, 24g protein, Informed Sport certified.
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📉 Lowest Rated Product
8.8/10
Gold Standard 100% Casein
28g micellar casein per scoop. Slow 5–7hr amino acid release — the best pre-sleep protein available.
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Brand Analysis
Optimum Nutrition has maintained its position as the world's most trusted sports nutrition brand for nearly 40 years. The brand was acquired by Glanbia in 2008 and has maintained its quality standards through the transition. Their core protein products have been independently validated across hundreds of studies.
Gold Standard 100% Whey is the benchmark protein supplement. The WPI-first blend, Aminogen® enzyme system, Informed Sport certification, and sub-$1 per serving cost at the 5lb size represent a combination no competitor has consistently matched across two decades. Serious Mass remains the reference mass gainer; their creatine and amino line are competent but don't lead their respective categories.
The brand's main limitation is disclosure depth on the WPI:WPC ratio in Gold Standard Whey. For most buyers, this is a non-issue given the product's 25-year track record. Their pre-workout range is conservative on dosing relative to Transparent Labs and Legion.
📦 All Products by Category
13 products across 6 categories · 2 reviewed · 11 reviews coming soon
✅ Reviewed
In Stock
Gold Standard 100% Whey
9.8/10WPI+WPC24g ProteinInformed Sport
Price: From $0.88/serving
The world's best-selling protein for 15 years. WPI-first blend, 24g protein, Informed Sport certified.
✅ Reviewed
In Stock
Gold Standard 100% Casein
8.8/10Micellar Casein28g ProteinPre-Sleep
Price: From $1.12/serving
28g micellar casein per scoop. Slow 5–7hr amino acid release — the best pre-sleep protein available.
In Stock
Gold Standard Natural 100% Whey
Natural SweetenersWPI+WPC24g Protein
Price: From $1.05/serving
Same WPI-first formula with natural sweeteners only — stevia instead of sucralose and Ace-K.
In Stock
Gold Standard 100% Plant
Plant ProteinVegan24g Protein
Price: From $1.80/serving
Pea + brown rice plant protein blend. 24g protein per scoop. Certified Vegan.
In Stock
Serious Mass
Mass Gainer1250 Cal50g Protein
Price: From $1.80/serving
1,250 calories per 2-scoop serving. 50g protein, 252g carbs. The reference mass gainer for hard gainers.
In Stock
Pro Gainer
Mass Gainer650 Cal60g Protein
Price: From $1.60/serving
650 calories per 2 scoops. Lighter than Serious Mass — better for lean bulking.
In Stock
Micronized Creatine Monohydrate Powder
Creatine Monohydrate5gMicronized
Price: ~$0.10/serving
5g pure micronized creatine monohydrate per serving. Unflavoured, mixes easily, no loading required.
In Stock
Gold Standard Pre-Workout
Pre-Workout175mg CaffeineInformed Sport
Price: ~$1.20/serving
175mg caffeine, 1.5g beta-alanine, 3g citrulline. Informed Sport certified. Conservative but well-formulated entry-level pre-workout.
In Stock
Gold Standard Pre-Workout Advanced
Pre-Workout300mg CaffeineAdvanced Formula
Price: ~$1.50/serving
300mg caffeine, 4g citrulline, 1.5g beta-alanine. Stronger stimulant profile for experienced users.
In Stock
Gold Standard BCAA
BCAA5g2:1:1 Ratio
Price: ~$0.80/serving
5g BCAAs (2:1:1 ratio) plus electrolytes and B vitamins. Good for intra-workout use.
In Stock
Essential Amino Energy
EAA100mg CaffeineIntra-Workout
Price: ~$0.75/serving
EAA + caffeine blend. 5g EAAs, 100mg caffeine. Popular for fasted training and light energy.
In Stock
Opti-Men Multivitamin
MultivitaminMen75+ Ingredients
Price: ~$0.25/serving
75+ ingredients. Amino acid blend, antioxidants, phytonutrients — a comprehensive sports multivitamin for men.
In Stock
Opti-Women Multivitamin
MultivitaminWomen40+ Ingredients
Price: ~$0.25/serving
Formulated for women's specific nutritional needs. 40+ active ingredients including iron, calcium, and folic acid.
🧪 Lab Testing History
PASSGold Standard 100% WheyJan 2026Informed Sport
PASSGold Standard 100% CaseinJan 2026Informed Sport
❓ Frequently Asked Questions
Is Optimum Nutrition a good brand?+
Yes — consistently ranked as the world's most trusted sports nutrition brand. Core protein products are best-in-class for ingredient quality, certification, and value.
Is Optimum Nutrition Informed Sport certified?+
Yes. Both Gold Standard Whey and Casein carry Informed Sport certification — tested for 280+ banned substances per batch.
What is ON's best product?+
Gold Standard 100% Whey (9.8/10) — best combination of protein quality, value, certifications, and consistency of any protein supplement we've reviewed.
What is ON Serious Mass used for?+
Caloric surplus for hardgainers — 1,250 calories and 50g protein per 2-scoop serving. Best for people who struggle to eat enough calories from whole food alone.
Does ON use proprietary blends?+
No for protein. Full amino acid disclosure on every label. The WPI:WPC blend ratio is not disclosed — the one transparency gap.