Casein Protein Side Effects - Slow-Moving Danger
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Casein Protein Side Effects – Slow-Moving Danger

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Slow Danger

We’ve all heard of the substance that is used throughout many products to eat more protein; whey. It’s the most popular source for making protein powders, protein bars, and other dietary supplements. However, to the surprise of many people, whey protein has a brother that also gets incorporated into different supplements. It’s more of a little brother, known as casein. If you’re in and out of the supplement market, you’ve most likely heard of casein. It does provide distinct benefits whey can’t offer, but how are the casein protein side effects? How severe are they, and how does it compare to whey? Let’s find out.

What Is Casein?

Before getting into what side effects casein can plague you with, it’s essential to discuss what exactly casein is, and why people take it. It isn’t as popular as whey, nowhere near for that matter, but it’s still taken by a lot of people for certain reasons.

How’s Casein Protein Made 

There’s a process that manufacturers use to create to create casein. Interestingly enough, it’s the same process companies use to also create whey. It all starts with our favorite white-colored dairy liquid, milk. Both whey and casein come from milk, classifying them both as dairy products with lactose. (Having lactose will come back later in this article, keep in mind) This is why I call whey and casein brothers since they come from the same mom or source I should say.

Casein Protein Side Effects - Slow-Moving Danger

The goal of the process is to separate whey and casein, and this is done by adding certain enzymes to milk. What we get from the milk are two bi-products, a liquid substance, and solid chunky substances. The liquid part is the whey protein; it’s dehydrated into powder and used for all types of substances, simple. The chunky bits are the casein, also used in products like cheese and yogurt. From here, we got our casein, and manufacturers purify it for it to be usable in supplements.

Why Is Casein Protein Neglected?

At this point during the process, everything is pretty much wrapped up. We’re not getting into the additives thrown in or marketing done by companies, maybe another time. The exact same process is used to create either protein, but whey takes most of the fame while casein is left in the dust. Why is that? Well, a couple of reasons. Probably the biggest reason is due to the price differential. Take a look at this bar graph below I created comparing two products made by one of the most trusted supplement company there is to date, Optimum Nutrition.

Casein Protein Side Effects - Slow-Moving Danger

The price of their whey protein is at $60 for 5lbs of protein powder. The casein is priced at $67 for 4lbs of protein powder. Looking at that, you notice something fishy. You get more protein for less money when choosing whey, while you’ll more for casein, for less powder. This is one of the main reasons why people steer away from casein. That and also the taste of it may cause some concern. Many caseins taste chalky, which most people don’t find appealing. I have a full list of why casein is left in the shadow from this article here, is quite long.

Side Effects

After taking a look at the properties of casein, it’s time to look at the side effects. I have listed three things that make many consumers raise some suspicion when deciding to buy a casein protein powder. To be honest, I still have to do extra research sometimes, when I want to buy a casein protein just to be safe.

Digestible Issues

This side effect not only goes for whey protein but also for its brother casein protein. The way the protein is digested by our stomaches can go one of two ways; a smooth passing, or a bumpy disaster. It all mainly has to do with people being lactose intolerant, a digestive disorder that occurs when the sugar in milk, lactose, is present in the body. Since both whey and casein have lactose, you’ll expect more or less the same problems. So why exactly are you or someone you know lactose intolerant?

To break down lactose in our stomachs, we need a certain enzyme to help our bodies do that. This enzyme is called lactase, a convenient name. Our bodies produce different amounts of lactase, respectively. If your body produces enough lactase, the lactose will be digested smoothly by your body without any problems. (These people are lactose tolerant, or the lucky ones.) If your body does not produce enough lactase, you’ll experience the known symptoms related to lactose intolerance.

This is because the leftover unbroken down lactose just sits there in your stomach fermenting. It’s then taken to the colon, and once it gets there, your stomach is in for it now. A couple of symptoms include diarrhea, bloating, gassiness, upset stomach, abdominal cramps, and or vomiting. Things you do not want to experience, trust me. If you are lactose intolerant, I advise switching to dairy-less protein powder for the sake of your stomach.

Allergic Problems 

Moving on to another problem that casein may present, I’ll discuss its allergen factor. Many people think that lactose intolerance is actually an allergic reaction. However, that is not the case. An allergic reaction involves your immune system reacting to a foreign substance in your body. Lactose could be classified as a foreign substance, but your immune system has nothing to do with being lactose intolerant.

It’s common to be allergic to milk, and therefore casein. You could experience a lot of the same symptoms as that of lactose intolerance. However, it may go farther than that. Certain symptoms are classified as anaphylaxis reactions. In short, these are deadly reactions, severe reactions. The list includes shortness of breath, wheezing, swelling of eyes, rashes, and possibly shockOnce again, switch to another protein powder if you know you are prone to some of these allergic reactions.

Harmful Substances 

This is one of the main reasons why people see a lot of controversy in protein powders. In 2018, a group of people puts the integrity and honesty of manufacturers to the test by inspecting their products. Conducted by the Clean Label Project, they set forth a mission to see what ingredients were actually used in their protein supplements. They wanted to inform consumers, like you and me, about what companies got going on behind the curtain. Their results? Shocking.

Casein Protein Side Effects - Slow-Moving Danger

A handful of protein powders contain toxic substances such as lead and arsenic. The substance arsenic is a known causer of cancer, something no one wants in their protein powder. These findings were headline-worthy to expose what companies were really doing. Imagine going to buy protein powder, thinking that the worst thing you’d be consuming would be artificial flavoring according to the ingredients label. But in reality, it’s a toxic substance that is nowhere listed on the supplement. It caused some outrage, still to this day.

How can protein powder companies get away with this? Well, unbeknownst to the public, protein powders aren’t actually regulated by the Federal Drug Administration or FDA. Meaning, companies don’t need the approval of the FDA to sell products. They can add whatever they like and get away scot-free since they’re supplements. The Clean Label Project refuses to take that sitting down and are petitioning to have them regulated by the government. If you’re on board with that, I’ll leave a link to their site here if you’d like to check it out.


In the conclusion of the side effects in casein protein, you can see they’re a handful of them. These are things to watch out for when deciding to purchase a casein protein powder for yourself soon. The possibility of lactose intolerance, allergic reactions, and or harmful substances concern the consumer. This is why it is essential to be cautious when buying and do your own research to see if the product you’re interested in is worth the bucks.

Got any questions? Leave them down below, along with any comments you may have!