One of the top sources of long-lasting amino acids, casein protein provides easy-to-digest protein in a similar fashion to whey. One of casein’s greatest advantages is the timing of how it’s absorbed, plus how long it lingers in the body. Both factors make it beneficial for building muscle fast and preserving the body’s lean muscle tissue.
When it comes to nutrient timing, the type of protein matters. Casein protein hits your bloodstream very quickly — plus its amino acids stay where they need to be in order to help build muscle tissue for many hours, as opposed to being flushed from the body relatively quickly.
Derived from milk, just like whey protein, casein protein is actually a naturally more abundant source of BCAAs. That’s why it’s sometimes simply called “milk protein,” since around 80 percent of the protein found in cow’s milk is casein — and it also makes up 20 to 40 percent of human breast milk.
Casein is made up of various “building blocks” called essential and non-essential amino acids. The human body is able to make certain amino acids on its own (called non-essential) while others it cannot (called essential), making the essential kinds crucial to get through the foods you eat. Since plant foods don’t always provide the complete set of essential amino acids we need, animal foods — and sometimes convenient protein powders — are one way people make sure they cover their protein bases.
Casein protein powder is created in a lab from dehydrating parts of milk — the problem is that many forms are denatured and isolated, and may cause health issues. You’ll want to try to find casein protein that is from A2 beta-casein rather than A1 casein (see the difference below).
Whey protein and casein protein differ in terms of their bioavailability and effects on muscle synthesis. Although whey protein has many of the same benefits, it’s believed to cause more of a fast “amino acid spike” compared to casein.
There are certainly benefits to consuming both faster- and slower-releasing proteins; it really just comes down to your goals and schedule.
At the molecular level, within a protein source like casein various amino acids are branched together. Casein protein has a lower percentage of branched-chain amino acid compared to whey protein, which is one reason it’s slower to digest and also tends to work for longer. Because of its utilization and timing, casein increases protein synthesis a bit less than whey does.
On the plus side, it better stops the body from breaking down amino acids it already has available within your muscles. Whey protein also has more sulfur than casein, which can also change the way the body uses it.
Compared to casein, whey is a fast protein source, which means it provides amino acids quickly after ingestion — however they also leave the body sooner than when you consume casein.
Both casein and whey protein can supplement your workouts well and include all the essential amino acids you need, but whey has more branched-chain amino acids and, therefore, might be slightly better at facilitating muscle protein synthesis.
The good news is this: After comparing the effects of both proteins on body composition and performance in female athletes, researchers from the Exercise and Performance Nutrition Laboratory at the University of South Florida found that whey and casein had similar positive effects. Females were found to experience benefits using both supplements, including an increase in performance markers from consuming protein after resistance training and a decreased body fat composition.
The benefits of casein protein:
• Building new muscle tissue and promoting lean muscle growth (5)
• Repairing broken-down muscle fibers after a workout while you sleep
• Preserving muscle you already have (making it anti-catabolic)
• Restoring nitrogen balance during muscle recovery
• Curbing your appetite
• Regulating blood sugar levels
• Helping prevent overeating
• Potentially helping with weight loss/maintenance
The Best Times to Use Casein Protein
Ideally, you want to use casein protein before bed (if your goal is to build muscle and potentially gain weight) or as a meal replacement/snack between spaced-out meals. Remember that casein is digested slowly, which means following a workout it will take longer than other types of protein (such as whey) to reach your muscles.
Since you want to supply your damaged muscle tissue with nutrients ASAP following exercise, using casein over faster-acting protein sources won’t give you the benefits of an immediate rush of amino acids that you’re after. Because whey protein is so quickly absorbed and digested, it makes the better choice following a workout. Your muscles are searching for a rapid supply of nutrients after you train in order to carry out muscle synthesis, so hold off on having casein to better speed up this.
Nutrition facts
A serving of casein powder has around:
• 120 calories
• 23 grams protein
• 1 gram fat
• 1 gram sugar
• 450 milligrams calcium (45 percent)
Different Types of Casein Protein: A1 vs. A2 Casein
Milk is composed of about 85 percent water and 15 percent sugar (called lactose), protein, fat and minerals. Among the protein compounds in milk, there is more than one kind. A2 beta-casein is the type that has been produced naturally by animals for thousands of years, even before they were first domesticated more than 10,000 years ago. It’s believed to be easier to digest, and some research suggests it has much fewer effects on human health than the other type, called A1 casein.
A1 is the “newer type of casein,” which first developed sometime in the past few thousand years following animal domestication. It came about after certain genes caused proteins to change, resulting in proline amino acids changing over to histidine. Today, A1 beta-casein is more abundant in dairy cows that are used to produce the vast majority of milk in the U.S. and even Europe.
Each cow has a certain genotype of A1/A1, A1/A2 or A2/A2 that ultimately affects the milk it produces. It’s preferable to consume milk products, including all dairy foods and whey/casein protein supplements, made from cows (or goats) that predominantly contain A2 casein. How come?
When A1 beta-casein caused a switch from proline to histidine amino acids, it resulted in problems with humans digesting and properly metabolizing milk. In fact, most people who are intolerant of cow milk are actually sensitive to one of the proteins found in it, A1 casein. They essentially lack the ability to digest A1. This intolerance is now linked to a wide range of illnesses, including autoimmune reactions, food allergies, digestive issues, type 1 diabetes, heart disease and more. A1 is also thought to promote inflammation, however milk that contains mostly or exclusively A2 casein produces far fewer (or zero) inflammatory effects. Usually the grass fed whey products contain less A1 casein.
