By now you probably know the difference between whey and casein protein, well if not, casein protein is a very slow digesting protein while whey is fast-digesting. Casein protein can make an excellent meal replacement shake due to its slow digestion rate and steady amino acid release time. We at CHROME reviewed Optimum Nutrition’s Gold Standard 100% casein protein and below is what we think of it.


Faster digesting amino acids are desirable immediately before and after exercise to help refuel recovering muscles, but slow digestion and absorption may be more beneficial at other times – including bedtime when your body typically goes for hours without food.*

Casein proteins are acid sensitive and thicken in the stomach. Compared to some other proteins, it can take more than twice as long for Gold Standard 100% Casein to be broken down into its amino acid subcomponents. By using only premium micellar casein as a protein source, ON has created a formula that sets the standard for slow digesting protein support.


  • Best-Selling Micellar Casein
  • 75% Protein by Weight (24G of Protein per 32G Serving Size)
  • 24 Grams of Slow-Digesting Micellar Casein per Serving
  • Over 5 Grams of BCAAs (Leucine, Isoleucine and Valine) per Serving
  • Nearly 5 Grams of Glutamine & Glutamic Acid in Every Scoop
  • Very Low Levels of Fat, Sugar & Carbohydrates
  • Ideal for Use Between Meals and Before Bed



TASTE = 9.5/10

This all depends on what flavour you tried out, I was fortunate enough to try the chocolate flavour and it was divine. Not all companies have mastered the taste when it comes to casein protein, but after tasting Optimum Nutrition’s casein, I can now understand why their proteins are the #1 seller in the world.

MIX = 8.5/10

In general, a casein protein does not mix as easily as a whey protein, but I had no issues mixing Optimum Nutrition’s casein in my shaker. If preferred you can also mix it in a blender, but I found that a shaker works just fine.


Optimum Nutrition’s casein protein consists of 24 grams of protein per serving, along with a mix of BCAA’s and glutamine to the value of 10grams per serving. ON also included 24miligrams of Aminogen, in a nutshell Aminogen increases the rate of protein absorption in the body, meaning that you will be able to get more bang for your buck!

Try Optimum Nutrition Gold Standard 100% Casein For Yourself

Optimum Nutrition Gold Standard 100% Casein

Casein proteins are pH sensitive and gel in the acidic environment of the stomach. As a result, it can take more than twice as long for caseins to be broken-down into their amino acid subcomponents than whey and other proteins. Because of their unique time-released qualities, caseins are aptly described as anti-catabolic or muscle-protecting proteins.

OVERALL = 9/10

With approx. 75% protein per serving, with added Essential Amino Acids and Aminogen, you will never feel disappointed after purchasing this product.


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