Without protein, we can’t build, repair, or maintain muscle — it’s as simple as that. Studies have shown that exercise boosts the body’s protein turnover rate, so athletes, weight trainers, and fitness enthusiasts alike have increased needs for protein, which should be the foundation of any nutrition program.

Which protein is the “better” choice for achieving your performance goals: whey, milk protein, casein, or soy? This remains one of the hottest, highly debated topics in performance nutrition. The bottom line: once you know the differences, you can make a better choice for your goals.

Where to find Protein

Proteins are found in all animal and vegetable tissues and are made up of amino acids. After we consume proteins, they’re broken down by our bodies into amino acids again and then used to build new proteins — that is, muscles, enzymes, and even some hormones.

Popup: Foods highest in Protein

Daily Value

The Daily Value for Protein is 50 g.


Why athletes use Protein

As an active person, you require a diet rich in protein to enhance muscle recovery and growth, maintain hard-earned muscle tissue, and strengthen your immune system. But it can be difficult to meet our bodies’ protein needs entirely with whole-food meals. Luckily, great sources of protein, like whey, soy, milk, and casein, are available in convenient, inexpensive, and nutritious supplements.

Ways that Protein can enhance Muscle Gain & Recovery:

  • Provide an optimal source of amino acids (which are the major building blocks of muscle) needed for the repair and growth of muscle tissue
  • Increase the anabolic environment and prevent muscle breakdown, assisting the muscle-building effects of intense weight training

Ways that Protein can enhance Longevity:

  • Boost immune function by increasing levels of the most potent antioxidants in the body


Signs of Protein deficiency

Although a deficiency in the primary amino acids is unlikely, individuals who consume less dairy products and animal meats would require additional protein intake from alternative sources. And, active people, especially hard-training athletes and weight trainers, require greater amounts of protein than sedentary people.


More about Protein

Protein, a macronutrient, is essential, and our bodies are chockful of it. To visualize a molecule of protein, think of a very long chain. The links in the chain are amino acids, commonly known as the “building blocks of life,” which are, scientifically speaking, the building blocks of protein.

Those of us who regularly exercise require more protein (a lot more!) than sedentary folks. And, no matter what kind of diet you follow — whether it’s low or high in complex carbohydrates or fats — as an active person, you require a diet rich in protein. But it can be difficult to meet our bodies’ protein needs entirely with whole-food meals. Luckily, great sources of protein, like whey, soy, milk protein, and casein, are convenient, inexpensive, and nutritious supplements. Here’s a quick look at just a few of the many benefits of proteins:

Promote muscle building

Studies with both strength and endurance athletes have clearly indicated exercise increases our needs for protein. Studies appearing in the American Journal of Clinical Nutrition have also shown that the muscle-building effects of intense exercise may be increased by a high-protein diet. In fact, the more intensely we exercise, the more important dietary protein is if we want to maximize our muscle-building potential.

Boost Energy

Protein has a positive effect on insulin stability and energy levels: when consuming protein with each meal, blood sugar levels fluctuate less. This can help control our appetites and provide an environment for greater fat loss. Plus, protein provides consistent, sustained energy. While carbohydrates certainly provide fuel for our immediate needs, protein helps supply fuel over the long haul.

Enhance muscle recovery

Because protein has especially high concentrations of amino acids, it gives our bodies the nutrition they need to build, maintain, and repair muscle mass.

So just which type of protein is best?

In fact, each type of protein, whey, casein, milk protein, and soy, offers unique benefits. So depending on your goals, you may choose to “mix and match” different sources in varying ratios. Below is a brief summary of each type to help you decide which protein combination is right for you:

Whey protein, one of the two forms of protein derived from milk protein, is quite possibly the highest quality protein available. Considered by many experts as the foundation for building and maintaining lean mass, whey has gained a solid reputation as the “supreme” protein supplement because of five key qualities:

  • High bioavailablity (BV factor), which allows for faster uptake of amino acids into muscle cells than other forms of protein;
  • A rich amino acid content, including the two vitally important aminos glutamine and cysteine (direct precursors to the most powerful free-radical fighting amino, glutathione);
  • Enhanced immune-function-promoting levels of glutathione;
  • Impressive amounts of immunoglobulins and lactoferrin (big words for protein peptides that positively trigger the immune system); and
  • Low levels of lactose (milk sugar), calories, and fat.

What these elements add up to is that whey protein is the “must-have” for all active individuals.

The other protein derived from milk, casein, has been found in recent studies to not only supply the most critical amino acids our bodies need to spare muscle mass during intense training sessions but to even help increase muscle mass. Here’s a rundown of some of casein’s key qualities:

  • It’s an especially rich source of the immune-boosting and muscle-protein-sparing amino acid glutamine. In fact, it has a potent 20.5% glutamine content.
  • It’s also a great source of arginine, the well-known “growth-hormone-releasing” amino acid.
  • And because casein has one of the highest tyrosine-to-tryptophan amino acid ratios of any protein (almost 5 to 1), it’s also considered one of the most stimulating and may even help suppress appetite after consumed. This is because tyrosine is considered the “pick-me-up” amino acid that increases levels of excitatory chemical signals in the brain and therefore creates a sense of overall satisfaction and “fullness.”

Milk protein is usually not found by itself like its counterparts whey and casein. In fact, it’s usually part of a protein blend found in meal-replacements, nutrition bars, or protein drink mixes. Check out the Nutrition Facts on the labels of just about any of these products, and you’ll find that milk protein is added to other high-quality proteins (such as soy, albumin, etc.) to create a “proprietary protein blend.”

A combination of both whey and casein, milk protein is actually used more as a labeling cosmetic than anything else. And, the benefits of milk protein are literally the same as those of whey and casein. Which is logically since milk protein is 80% casein and 20% whey.

Even though soy was the first protein powder ever available to consumers searching for a protein supplement, it was considered “substandard” as far as a protein source for decades because it was labeled “incomplete” as compared to animal-source proteins. Now, thanks to science, it’s been vindicated. It is, in fact, a good protein choice, being a complete protein that’s low in fat and calories while high in benefits that women and calorie-restricted dieters may find appealing.

Studies with both male and female athletes have demonstrated that soy may help prevent the loss of muscle mass and improve performance while decreasing bodyfat, likely by promoting the release of hormones and potentially affecting metabolism. Soy has also been shown to promote strong bones, connective tissue, and reduce inflammation, helping reduce recovery time. Uniquely, some research suggests soy may also help maintain or even boost metabolism, even when calories are decreased.

*To discover additional benefits and learn more about whey protein, casein, milk protein, and soy, please refer to our complete supplement profile for each.

In conclusion

Which protein is the “better” choice for achieving your performance goals: whey, milk protein, casein, or soy? This will likely continue to remain one of the hottest, highly debated topics in performance nutrition. But now you know some of the basic differences between whey, soy, casein, and milk proteins, so you’re better prepared to decide which proteins are best for your goals — it may just be most beneficial to consume a balance of all the protein types.



Studies supporting optimal protein intakes indicate intensely training people need between 1 and 1.5 grams of protein per pound of bodyweight.


Protein can be consumed anytime throughout the day.

Synergists of Protein

No synergists have been noted.

Toxicity of Protein

No known toxicity.

Bans and restrictions

None reported.


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