Optimum Nutrition 100% Casein Protein Review

Casein Protein

Optimum Nutrition is one of the most well known protein supplements in the market today.

If you have a vague idea about protein supplements, you have likely heard about this brand. The company makes some of the best protein powder in the world.

Among their line of products, the 100% Casein Protein has to be the most popular supplement. This particular product has even won several awards. Many nutritionists consider it as the best casein based protein you can get.

What is Optimum Nutrition 100% Casein Protein?

The Optimum Nutrition 100% Casein Protein, also known as Gold Standard 100%, is a milk-based protein supplement. It also contains BCAAs, vitamins, and digestive enzymes.

This product is not for weight loss purposes. However, several athletes use this supplement to burn fat while gaining muscles. Several studies have also proven this.

The 100% Casein Protein was first introduced in 1986 and does not seem to have too many artificial ingredients. You can purchase this product from a local store or its official website.

Optimum Nutrition




The main ingredient in the 100% Casein Protein is micellar casein. But there are also several other ingredients which makes this product very effective. Let’s take a look at them


Aminogen is a digestive enzyme that helps in breaking down proteins. In simple terms, it helps the body in absorbing nutrients. Many professional athletes and bodybuilders take this substance to enhance their performance and achieve their body goals.

Aminogen is a great addition to the ingredient of any protein supplement, whether it is casein based or whey based.

It does not have any reported side effects


Lecithin, also known as soy, is a common food additive found in protein powders. This substance is a common allergen, and some people may experience mild side effects to it. It usually considered as a negative substance. However, lecithin is good for cholesterol markers and blood lipids.

Acesulfame Potassium

Acesulfame Potassium is an artificial sweetener found in several protein supplements.

The benefit of this substance is that it does not have any cholesterol. The main purpose of Acesulfame Potassium is to eliminate the bitter after taste of dietary supplements.

Some other ingredients of Gold Standard 100% Casein are:

Malic Acid
Beet Powder
Natural and artificial flavors

How to take:

Gold Standard 100% is a powder based supplement that you can take with water or any other liquid.

You can mix the protein with liquid by stirring with a spoon or a shaker. Besides water, most nutritionists mix it with almond milk or carbohydrate drinks to increase its effects. You can also add some fruits to make the shake tastier.

The recommended dosage of Gold Standard 100% is one scoop with 8 ounces of water. However, that depends on your body’s requirements. You can even take up to 3 scoops per serving.

The supplement is best taken between meals and before bed.

Benefits of Optimum Nutrition 100% Casein Protein

The benefits of Optimum Nutrition 100% Casein protein are way beyond what most products offer these days.

When you combine the supplement with resistance training, the result you get is hard to beat. In terms of bodybuilding and weight loss, it is easily one of the best protein supplements out there.

While Optimum Nutrition does not claim they are the best, its users’ response shows how good it is. The supplement’s benefits are also so well documented that the company does not need to advertise it.

The fact that the product is a casein supplement means that it will take longer to digest.

While it is desirable for protein shakes to dissolve faster, longer digestion period is more beneficial for the remaining day.

This is because slow digestion will provide a steady amount of amino acids to your muscles throughout the day.

A casein protein shake will usually cause a rise in the amino acid levels in your blood. This is very effective during the period after your workout when your muscle tissues are repairing.

You can also take this product before you sleep to provide your body with the nutrients it needs.

Since the protein powder from Optimum Nutrition is also slow to digest, it is perfect for serving between meals. In fact, you can also use it as a meal replacement drink.

Optimum Nutrition




Side Effects:

Optimum Nutrition 100% Casein Protein is a simple protein powder, so it is normally very safe.

However, if you are allergic to milk and milk products, you might experience some slight side effects.

The side effects may include cramps in the lower belly, diarrhea, wheezing, and irregular bowel movement. There are chances that you might feel nauseous after consuming the shake.

Some other serious side effects that a person with milk or soy allergy may experience are: 

Itchy skin
Swelling in various parts of the body like throat, lips, face, and tongue
Runny Nose
Pain in abdominal areas
Diarrhea and vomiting
Tingling sensation in the mouth

Stop the use of Optimum Nutrition 100% immediately if you experience the side effects mentioned above.

Does it work?

This protein supplement from Optimum Nutrition works quite well. However, as mentioned above, it may not be suitable for people with soy and milk allergy.

Besides that, if you work out regularly with intensive workout routines, the Gold Standard 100% will be very effective. You can build muscles much faster while also burn a great number of fats.

Without regular exercise, a person will usually experience poor or no results at all. In fact, you will likely gain more weight in the absence of a proper workout routine.


Slow digestion
100% Casein Protein
Comes with digestive enzymes
Low in fats and cholesterol


A bit expensive
Contains Soy


As far as casein supplement goes, the Optimum Nutrition 100% Casein is not the cheapest product in the market.

But the fact that it comes with a ton of benefits and great ingredients makes it worth the price. If you are looking for something to help you with your bodybuilding, then you’ll be pretty satisfied with this.

James Vaughan
James Vaughan
I'm James Vaughan. I am a bodybuilding and fitness enthusiast giving my honest reviews on all bodybuilding supplements including legal steroids and testosterone boosters. I also write articles and give advice on fitness and weight loss supplements.

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