Gold Standard Casein Review: is Optimum Nutrition’s Slow-Digesting Formula Worth it?

Image of chocolate casein protein powder

Gold Standard Casein is part of the famous "Gold Standard" product line designed by Optimum Nutrition, who also make a bunch of other supplements like creatine, bcaas, and pre-workout.

While not having the same popularity as their signature Gold Standard Whey, casein is becoming a must-have for bodybuilders and athletes seeking to maximize their strength and muscle mass.

And it's no surprise, as you'll soon find out.

After trying their whey protein, we decided to create a full Optimum Nutrition Gold Standard casein review, to check out the benefits for ourselves.

Optimum Nutrition Casein Nutrition Facts

Per serving, which is roughly 34 g, we get quite a decent nutritional profile from what is put simply, just a protein powder. A scoop gives us 24g of protein, and 50% of the RDI for calcium, which is sourced from 100% micellar casein.

Rounding off the rest of the calories (120) are a few grams of carbs (3 g) and a tiny bit of fat (1g), which is to be expected given that 80% of it sourced from milk proteins.









Micellar Casein




ON also include Aminogen™, which is a digestive enzyme, and as you'll find out later, it can be useful if you're really going hard on the protein intake. There's also the typical sweeteners (sucralose and acesulfame potassium) which are used to cover up the taste of the powder.

Now, let's see what these ingredients can actually do for us.

Gold Standard Casein Ingredients

The main ingredient here is micellar casein, a "slow protein" which is commonly found in your everyday foods like yogurt, cheese, and milk.

You might have heard stories of bodybuilders eating cottage cheese before bed, this is no weird ritual, cottage cheese is really high in casein, which keeps protein synthesis dialed up throughout the darker hours.

On the mineral side of things, there's a remarkable 50% of the RDI for calcium, which is a vital nutrient for muscle contractions, nerve functioning, and bone health.

It's also minimal in fats and carbs, making it an excellent nighttime shake because you won't go to bed feeling like you've just eaten Christmas dinner.

Who Can Benefit From Taking Gold Standard Casein?

Being a pure and remarkably simple supplement, anyone seeking to improve their physique or increase their protein intake can benefit from taking this protein formula regularly.

However, those who will enjoy the most noticeable effects, are those who do not currently consume any slow-digesting protein before bed. By not taking in a slow-digesting protein source before hitting the sack, the muscles can easily slip into a catabolic state as you sleep, leaving you vulnerable to being undercover and even muscle loss.

By skimping on slow-digesting protein before bed, you may well be missing out potential size gains.

Sleep is a gold rush for muscle growth, and by not timing your protein intake around it, you are missing out on what are potentially some of the best gains you'll make. Eating a whole foods meal can do the trick, but it's also cumbersome on the stomach, which is not at all ideal for sleep.

Thankfully, with the invention of supplements, we don't need to cram in bowls of cottage cheese to get the benefits of casein.

If you want to maximize muscle growth, then you may well benefit from taking ON Gold Standard Casein before bed. Go ahead and try, to see how it can improve your recovery rates.

How To Properly Use

To avoid catabolism and promote muscle growth, take Gold Standard Casein before bed with water or milk.

For all scenarios, use around 8-12 oz of liquid and shake hard for 25-30 seconds. For a sweeter shake, which is my preference, go with milk, or less water. To lessen the intensity, go for lower calorie milk, or just more use cold water.

In my experience, casein tends to be a little thicker than whey and requires more shaking to even out the mixture. This isn't a bad thing though, it's a good sign that you're actually getting the real ingredients.

We mixed Optimum Nutrition's Gold Standard Whey with just a spoon, but for their casein, we recommend using a shaker bottle and your strongest arm for best mixability.

Image of a shirtless man drinking a protein shake

Sizes, Servings, And Scoop

There are 3 sizes that you can pick from, which I've listed below along with the number of servings:

  • A regular 4 lb tub with 53 servings
  • Smaller 2 lb tub with 26 servings
  • A naturally flavored powder in a 4 lb tub with 48 servings

If you only take Gold Standard Casein before bed, even the smallest tub lasts nearly a month, which is good value considering its many benefits for the body.

As for the scoop size, it's 34 g in the regular tub, and just under 38g in the naturally flavored option.

The Available Flavors

Being part of the famous Gold Standard product line, it is available in a variety of flavors. Optimum Nutrition makes both artificially sweetened and naturally flavored powders, which cater to all kinds of taste palates.

Here are the regular flavors:

  • Banana Cream
  • Chocolate Peanut Butter
  • Chocolate Supreme
  • Cookie Dough
  • Cookies And Cream
  • Creamy Vanilla
  • Mint Chocolate Chips

Naturally Flavored

There is not as much choice with their naturally flavored options, but it's my best guess that most people like either chocolate or vanilla.

  • Natural Chocolate Creme
  • Natural French Vanilla

How Does It Compare?

If you are unsure whether Gold Standard ticks all the boxes, you can check out our comparison below, or click the link for our full guide on buying protein supplements.


Our Rating





Gold Standard Casein




Naked Casein




Dymatize Elite Casein




So, Should I Give It A Shot?

Overall, we feel that ON Gold Standard Casein is an excellent supplement in many ways. Using it regularly can help to prolong protein synthesis, reduce muscle breakdown at night, and keep you feeling full for longer, all while being more convenient than cottage cheese.

Anyone can use this supplement. Whether you're a competitive bodybuilder, amateur athlete, or are merely seeking to increase your diet's calcium content, give Gold Standard casein a try and see its effects for yourself.

Compared to Gold Standard Whey, we found the consistency of the powder to be on the thicker side, and mixability wasn't as instantaneous. However, this is characteristic of most caseins we've tried, and given the desirable effects the protein can have, we don't think you'll mind shaking your bottle a little bit more vigorously.

We hope that you like our Optimum Nutrition Gold Standard Casein review and hopefully, it helps you decide which brand to buy.

Optimum Nutrition Casein | Releases Amino Acids Slowly

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Jonathan Abbott
Jonathan Abbott
Jonathan is a long time fitness enthusiast who specializes in helping others reach their goals faster with the most up to date sports science. When he's not working, you'll find him challanging his body with heavy squats and deadlifts.

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