Milk is known as one of the best sources of high-quality protein for humans. According to nutritional analysis, milk also contains a little of nearly every nutrient you need to get from your diet every day.

But that’s not all milk has to offer. In a 2016 review, Iranian researchers compiled evidence of milk’s many medicinal properties, which are not highlighted as often as its nutritional benefits. The researchers attributed these properties to the major proteins in milk, which serve as its most bioactive components.

The health-promoting components of milk

Milk proteins make up about 38 percent of milk’s total solid content excluding fats. They are usually classified as either whey protein or casein. Whey protein accounts for about 20 percent of the total protein in cow’s milk, while casein accounts for the remaining 80 percent.

Whey protein refers to a group of globular proteins found in the watery portion of milk (whey) that separates from the curd during cheese-making. These proteins are described as heat-labile, meaning they are easily destroyed or altered by heat. Examples of these proteins include serum albumin, lactoferrin, immunoglobulins and alpha-lactalbumin.

Despite the instability of whey protein, it has high nutritional value and is also easily absorbed, as well as efficiently utilized, by the human body. And because it provides a considerable amount of amino acids, which the body uses to make its own proteins, whey protein has become popular among athletes and bodybuilders. Protein is the building block of muscles and is essential for gaining muscle mass and strength.

Casein, on the other hand, is a family of milk proteins composed of four major components, namely, alpha-, beta-, gamma- and kappa-casein. As a whole, casein is considered a complete protein because it provides all nine essential amino acids your body needs but can’t produce on its own.

In contrast to whey protein, casein is slowly digested by the body, so it releases amino acids at a much slower rate. This makes casein a great supplement for supporting muscle repair after strenuous exercise. In fact, people who supplement with casein take it before going to bed to support muscle recovery and prevent muscle breakdown while they sleep.

Health benefits of whey protein and casein you might not know about

Numerous studies have shown that milk proteins are not just for growing muscles and improving physical performance. In their article, Iranian researchers discussed how whey protein and casein can benefit your health in surprising ways, thanks to the following properties:

• Anticarcinogenic — According to cell culture studies, whey protein offers protection against certain cancers. Researchers believe that this is because whey protein helps increase your cells’ glutathione levels by providing the amino acids needed for its production. As a potent antioxidant, glutathione can protect your cells from oxidative stress, which promotes the growth and progression of tumors. Meanwhile, casein has been shown to prevent colon cancer in mice by stimulating and increasing the number of certain immune cells responsible for fighting cancer.
• Immune-modulating — Animal and cell culture studies show that whey protein helps regulate immune responses. For instance, whey protein helps increase antibody responses in the presence of allergens and bacterial toxins. It has also been found to normalize the number of white blood cells in cancer patients.
• Antimicrobial and antiviral — Some proteins in whey, such as lactoferrin, have antibacterial effects against known pathogens like group A Streptococcus (GAS) bacteria, which cause strep throat, impetigo and cellulitis, and Helicobacter pylori, which causes stomach ulcers. Proteins like alpha-lactalbumin and beta-lactoglobulin have also shown inhibitory activities against enzymes involved in viral replication.
• Anti-cariogenic — The protective effects of milk protein also extend to your teeth. Research has found that whey protein and casein help protect against tooth decay by preventing oral pathogens from forming biofilms on the surface of your teeth. This biofilm is commonly known as dental plaque. Kappa-casein has also been found to inhibit the activity of a plaque-promoting enzyme.
• Hypocholesterolemic — A series of studies have reported that casein can help reduce total blood cholesterol levels, particularly low-density lipoprotein (bad) cholesterol, in healthy individuals. Casein supplementation has also caused significant improvements in people with high blood cholesterol or a high risk of developing heart disease.

Milk is one of the oldest and most widely consumed foods in the world. It is also one of the most beneficial to your health because of the bioactive proteins it contains. Enjoy good nutrition, cancer protection and better cardiovascular and immune function by taking advantage of the health-promoting properties of whey protein and casein in milk.

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