Casein is a protein found naturally in milk. It is the main source of protein in cow's milk, making up around 80% of the total protein content. But what about other dairy proteins? What type of casein should I choose? What foods contain casein? We'll answer all these questions. In this article, as the title suggests, we'll be focusing more on the undesirable effects of casein consumption. As you will discover, this product is not necessarily suitable for all athletes.
What is casein?
There are two main forms of casein: calcium caseinate and micellar casein. Calcium caseinate is the form most commonly used in dietary supplements, while the more natural micellar casein is considered to be of higher quality.
Casein is present in many foods, including dairy products such as cheese, yoghurt, ice cream and butter. It is also used as a food additive to improve the texture and flavor of certain foods.
In the world of bodybuilding and sport, casein is consumed in powder form. It is thought to help preserve muscle mass and promote recovery after training.
What are the side effects of taking casein?
Casein is not all good news. Some athletes complain of itching or other intestinal problems after consuming casein. These digestive problems may be linked to an allergy to casein or cow's milk proteins in general (very rare in adults), lactose intolerance or an effect due to other compounds in the powder. These conditions can cause similar symptoms. So how can you tell them apart?
A casein allergy is an immune system reaction to casein protein. Symptoms can include skin problems such as eczema, respiratory problems and, in the most severe cases, an anaphylactic reaction.
When we speak of cow's milkprotein allergy , we are most often referring to a reaction to several proteins present in cow's milk, not just casein. Symptoms can be similar to those of casein allergy. The potential dangers of commercial milk proteins are therefore real, even if such events are very rare.
Finally,lactose intolerance is caused by an inability to digest lactose, the main sugar in milk and dairy products, due to a deficiency in the enzyme lactase. It can lead to digestive symptoms such as bloating, gas and diarrhea.
| Symptoms | Casein allergy | Milk Protein Allergy | Lactose intolerance |
|---|---|---|---|
| Skin symptoms (rash, urticaria, eczema) | Yes | Yes | No |
| Digestive disorders (diarrhea, nausea, abdominal pain) | Yes | Yes | Yes |
| Respiratory symptoms (nasal congestion, asthma) | Yes | Yes | No |
| Severe symptoms (anaphylactic shock) | Yes | Yes | No |
| Bloating and gas | Sometimes | Sometimes | Yes |
| Usually appears a few hours after consumption | Very fast | Very fast | Yes |
| Requires total avoidance of milk and milk-derived products | Yes | Yes | No |
Please note that these symptoms may vary depending on the individual and his or her state of health. It is always advisable to consult a healthcare professional if you suspect a food allergy or intolerance.
Is casein bad for you?
Casein consumption is not inherently unhealthy, provided the individual has no allergies or intolerances, and there is no underlying kidney disease. However, some studies1 have raised concerns about its harmful long-term effects.
Some research has suggested that casein consumption may increase the risk of certain types of cancer, although the results are still widely debated and should be taken with caution.
Casein powder, like other types of protein powder, could also present risks if consumed in excess. Although a popular protein source for athletes, over-consumption of protein can be harmful to the kidneys and liver. What's more, as with many of these ready-to-use products, some casein supplements may contain additives or potentially harmful ingredients.
It's important to remember that self-diagnosis and self-treatment can be dangerous. If you suspect an allergy or intolerance to casein, or are considering adding a casein supplement to your diet, you should always consult a healthcare professional.
What are the benefits of casein?
Despite the concerns it raises, casein is still of interest to sportsmen and women.
Casein is rich in essential amino acids, necessary for the body to function properly. As a slow-digesting protein, it also helps prolong the feeling of satiety, which can be beneficial in weight-loss diets.
In the context of bodybuilding, casein is often favored for its ability to support muscle growth and recoveryover long periods, particularly during sleep. Its slow absorption allows continuous diffusion of amino acids into the bloodstream, promoting muscle protein synthesis. That said, no study has yet succeeded in clearly proving an advantage to casein consumption over whey taken before bedtime.
When should I eat casein?
Like other protein powders, this product makes a good dietary supplement, but you still need to know when to use casein. This supplement is potentially useful for individuals seeking to build muscle. Its slow digestion allows for a prolonged release of amino acids, promoting muscle protein synthesis over a longer period.
This characteristic would make it ideal for consumption before bedtime, to provide a constant flow of nutrients to muscles throughout the night, thus promoting muscle recovery and growth during sleep. Despite this, it is quite possible to achieve this "slowed digestion" aspect with whey, notably by accompanying the intake of whey with a bowl of food, taking it as a dessert for example.
Like whey, casein can also be of some help when dieting. Thanks to its high satiety power, it can help control appetite and reduce snacking between meals. By incorporating casein or whey into your meals, or taking it as a snack between meals, you can reduce your total calorie intake while preserving your muscle mass.
To explore this point further:
Can you put on weight by taking casein?
How much casein should I take to lose weight?
It's important to remember, however, that the consumption of casein or any other protein powder should form part of a balanced diet and a suitable training program. Whether for weight gain or weight loss, casein or whey should not be the only source of protein in the diet.
Also be sure to eat a variety of protein-rich "classic" foods to get a full spectrum of amino acids.
What can I do if I'm intolerant to casein?
If you're intolerant to casein, you'll probably need to avoid foods containing it. Above all, as we explained earlier, it's important to know what kind of intolerance you have.
If you suffer from a real allergy, this means avoiding most dairy products, as well as processed foods that may contain dairy products in their composition. In the case of lactose intolerance, it's enough to choose only lactose-free or low-lactose products, which is quite possible for certain milk proteins such as whey or casein.
| Alternative | Source | Benefits | Disadvantages |
|---|---|---|---|
| Soy protein | Soybeans | Vegetarian alternative | Less interesting amino acid profile, origin of raw materials, solvent-based production methods |
| Pea protein | Peas | Vegetarian alternative | Less interesting amino acid profile, origin of raw materials, solvent-based production methods |
| Rice protein | Brown rice | Vegetarian alternative | Less interesting amino acid profile, origin of raw materials, solvent-based production methods |
| Hemp protein | Hemp seeds | Vegetarian alternative | Less interesting amino acid profile, origin of raw materials, solvent-based production methods |
| Egg protein | Egg white | Rapid absorption, rich in essential amino acids | May cause allergies in some individuals - quality & origin of raw materials |
| Whey protein | Milk | Rapid absorption, rich in essential amino acids, a benchmark for muscle recovery | Can potentially cause allergies and intolerances in some individuals |
Please note that each type of protein (vegetable, whey, casein...) can be very different from one brand to another, depending in particular on composition, origin of raw materials... It is important to carefully analyze the products offered by a brand before making your choice.
Generally speaking, from a nutritional point of view, whey is now considered the best alternative.
The question of choosing between whey and casein therefore theoretically doesn't arise, especially if you have a certain intolerance to casein. However, whey protein has slightly different properties to casein. It is a rapidly assimilated protein, usually consumed post-workout.
| Whey | Casein | |
|---|---|---|
| Source | Milk | Milk |
| Digestion speed | Fast | Slow |
| Optimum use | Post-training for recovery and optimization of training effects | Before bedtime for protein intake during sleep |
| Amino acid profile | Naturally rich in branched-chain amino acids (BCAAs) | Naturally rich in branched-chain amino acids (BCAAs) |
| Effect on muscle mass | Promotes muscle growth in conjunction with training | Promotes prolonged muscle growth through a constant supply of nutrients |
In conclusion, casein is a protein found in cow's milk that can be beneficial to sports performance, provided it is used in specific situations and there are no allergies or intolerances. However, scientific studies confirming the superiority of casein over other proteins such as whey are lacking. On the subject of risks, we also return to this subject in our dossier on the dangers of whey proteins.
