Casein comparison
Ascent Micellar Casein vs Optimum Nutrition Gold Standard 100% Casein
Ascent Casein scores higher on our standard, 84/100 to 63/100. It earns more points for third-party testing (Informed Sport vs none found) and ingredient simplicity (natural flavors vs mixed natural and artificial), while ON Gold Standard Casein earns more for protein density (71% vs 69% protein by weight). We could not verify a current price for ON Gold Standard Casein, so we can't compare cost.
Both are scored out of 100 against our published standard: protein density, third-party testing, label transparency, sugar, ingredient simplicity and verified label data. Every number below is from the manufacturer's label; last checked 2026-10-14.
Optimum Nutrition
Gold Standard 100% Casein
Side by side
Per serving, from each label. Bold marks the better score, protein density, sugar and cost where the two differ. How we score
| Compared | Ascent Casein | ON Gold Standard Casein |
|---|---|---|
| Our score | 84/100 (better) | 63/100 |
| Protein density | 14 / 3069% of each scoop is protein | 22 / 30 (better)71% of each scoop is protein |
| Third-party testing | 25 / 25 (better)Lot-tested for banned substances | 0 / 25No verified independent testing program |
| Label transparency | 20 / 20Fully disclosed formula, no amino spiking | 20 / 20Fully disclosed formula, no amino spiking |
| Sugar | 10 / 101 g sugar per serving | 10 / 101 g sugar per serving |
| Ingredient simplicity | 10 / 10 (better)Natural flavors and sweeteners | 6 / 10Mix of natural and artificial flavors or sweeteners |
| Verified label data | 5 / 57 of 7 label values verified | 5 / 57 of 7 label values verified |
| Type | Casein | Casein |
| Protein per serving | 25 g | 24 g |
| Serving size | 1 scoop (36 g) | 34g (About 1 Scoop) |
| Protein by weight | 69% | 71% (better) |
| Sugar | 1 g | 1 g |
| Calories | 120 | 120 |
| Cost per 25 g protein | $1.80 | Not verified |
| Price per serving | $1.80 | Not verified |
| Third-party certifications | Informed Sport | None found |
| Sweeteners | Stevia Leaf Extract | Acesulfame Potassium, Sucralose |
| Allergens | Milk | Milk, Soy |
| Proprietary blend | No | No |
| Added free amino acids (amino spiking) | No | No |
| Last checked | 2026-10-14 | 2026-10-13 |
Which to choose
Only the differences in our records. A value we couldn't verify never counts as a difference.
Choose Ascent Casein if…
- You want a powder lot-tested for banned substances (Informed Sport); we found no third-party testing for ON Gold Standard Casein.
- You prefer natural flavors and sweeteners (ON Gold Standard Casein uses a mix of natural and artificial ones).
- You avoid soy: ON Gold Standard Casein's label lists it as an allergen and Ascent Casein's does not.
- You want a powder the brand labels gluten-free (our record for ON Gold Standard Casein has no such label).
Choose ON Gold Standard Casein if…
On the label facts we track, ON Gold Standard Casein has no clear edge over Ascent Casein. Taste, how it mixes and the price where you shop may still decide it.
The two powders
Good to know
Labels and prices change, so check the package before buying, especially if you have allergies. If you are pregnant, nursing, buying for a child or managing a health condition, ask your doctor before adding a supplement.