Optimum 100% Casein Protein, 4 lbs
Optimum Nutrition 100% Casein Protein — 4 lbs (56 Servings)
Optimum Nutrition 100% Casein is the world's best-selling micellar casein — and for good reason. At 75% protein by weight, it delivers 24g of slow-digesting micellar casein per 32g serving, providing a sustained release of amino acids over 5–7 hours. This makes it the definitive nighttime protein: taken before bed, it continuously feeds muscle tissue through the overnight fast when you'd otherwise be in an amino acid deficit. Each serving also provides 40% of your daily calcium requirement — a significant nutritional bonus alongside the muscle-preservation benefits.
| Spec | Per Serving (32g) |
|---|---|
| Brand | Optimum Nutrition |
| Size | 4 lbs (56 servings) |
| Protein | 24g |
| Calories | ~110–120 |
| Fat | ≤1g |
| Sugar | 1g |
| BCAAs (naturally occurring) | ~5g |
| Calcium | 40% DV |
| Protein Type | Micellar Casein (slow-digesting) |
| Available Flavours | Chocolate Supreme, Creamy Vanilla |
Key Benefits
- Micellar Casein — 5–7 Hour Release — Unlike whey protein which digests in 1–2 hours, micellar casein forms a gel in the stomach that releases amino acids slowly over 5–7 hours — providing anti-catabolic protection during sleep and extended fasting periods.
- 24g Protein at 75% Protein by Weight — One of the highest protein densities in any slow-digesting protein formula on the market. Minimal carbs and fat means the calories are almost entirely protein.
- 40% Daily Value Calcium Per Serving — Micellar casein is naturally calcium-rich. For athletes, adequate calcium supports muscle contraction, bone density under heavy loading, and overall metabolic function.
- 5g Naturally Occurring BCAAs — Including leucine, isoleucine, and valine to support overnight muscle protein synthesis and reduce muscle breakdown through the fast.
- 56 Servings per 4lb Container — Nearly two months of nightly use in a single tub at a cost-efficient per-serving rate.
Best For
- Nighttime use before bed to prevent overnight muscle catabolism
- Between-meal slow-release protein to maintain a positive nitrogen balance throughout the day
- Athletes in a calorie deficit who want maximum muscle preservation
- Stacking with whey protein for a complete fast + slow protein protocol
Not Ideal For
- Post-workout use where fast absorption is the priority — use whey instead
- Those with dairy or lactose intolerance (micellar casein is a milk protein)
Ingredients & Allergens
Primary protein source: Micellar Casein. Other ingredients vary by flavour and include natural and artificial flavours, cocoa (Chocolate Supreme), cellulose gum, soy lecithin, sucralose. Contains: MILK, SOY. Confirm the complete ingredient list for your specific flavour on the product label before use.
Who Is This For?
Optimum Nutrition casein protein is ideal for athletes and gym-goers who want a slow-digesting protein to support overnight muscle protein synthesis and recovery. It works best as a pre-bedtime protein source or as a filling, sustained-release protein between meals.
Who Is This NOT For?
Not suitable for individuals with dairy or milk allergies. Casein is a slow protein — it is not the best choice for immediate post-workout recovery where fast-absorbing whey is preferable.
Why Buy From Bulldog Nutrition?
Bulldog Nutrition is an authorized Canadian and US retailer of Optimum Nutrition products. We source directly from the brand — never from grey market or unauthorized distributors — so every order is genuine and fresh.
- ✓ Authorized Optimum Nutrition retailer — authentic products only, never grey market or counterfeit
- ✓ Ships across Canada and the US — fast, reliable delivery to your door
- ✓ 10+ years in business — a track record you can rely on
- ✓ 4.7/5 stars from 2,400+ verified customer reviews
- ✓ Ongoing support available — reach us anytime via email or live chat
Shipping Information
Bulldog Nutrition ships across Canada and the United States. Most orders are processed within 1 to 2 business days.
Free shipping is available on eligible orders over $100. Please note that drink cases are excluded from free shipping due to size and weight.
During extreme hot or cold weather, heat-sensitive or cold-sensitive items may be affected in transit. For full details, please review our Shipping Policy.
Product & Site Disclaimer
Website information is provided for general informational purposes only. Product details, images, ingredients, and labels may change without notice, so customers should always review the actual product packaging received before use. For full details, please review our Product & Site Disclaimer.
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