The Difference Between Whey and Casein Protein

Milk is For Babies: Why Whey is Better Than Casein

"I maintain that if you took a group of identical twins, trained them the same way, and maintained duplicate conditions for all of them, with the exception of giving them different proteins, you'd see zip difference after a year." - TC Luoma, Editor, Testosterone Magazine.

A new debate is forming in the bodybuilding world. For the past little while, whey, or more specifically, whey protein isolate has been the Lennox Lewis of proteins. In other words, whey is the undisputed champ. Lately though, another protein has come along to take on the champ, but this challenger is more like the Butterbean or proteins: Some people are starting to say that casein is better than whey.

Wait a minute here. I thought science is supposed to move forward, not backwards.

Well folks, science is only part of the reasoning behind casein's/milk proteins re-emergence. You see taste has become the number one way for protein supplements to distinguish themselves. Let's face it, other than one or two new breakthroughs, the protein market is at a standstill. Patents are preventing many would be copycats from knocking off the new top products, so companies with smaller research budgets have decided to re invent MRP's by making them tastier than ever. "Okay, so why not use whey then?" Simple. Whey protein isolate taste like shit. High quality whey protein isolate tastes bitter, and it's costly to produce a good tasting all whey MRP. Casein and other milk proteins on the other hand, can be made to taste as good as any milkshake you've ever had and in most cases at a lower cost! Two birds with one stone baby. We live in a scientific world though, so to complete the puzzle, new tests have to be done (on overweight police officers among others) that show casein is superior at building muscle. There you have it, great taste and studies that show it's better than what we are used to.

Ready to switch to a casein supplement yet? Well stop right there dude. You see, this "guru" (me) doesn't quite see eye to eye with the pro-casein crowd. Frankly I don't see how casein warrants this much attention. There are just too many factors to consider about a supplement containing casein. What's the moisture, residual lactose and ash percentage? Is it potassium or sodium caseinate? What temperature was the protein dried at? How long has it been sitting in the warehouse? (A key issue, because amino acids continue to deteriorate after heat is applied. It's called the Malliard effect). Because heat-treated Casein is less digestible, more of it reaches the large bowel where it can be fermented by intestinal flora. When the Casein ferments it can produce ammonia and a variety of phenols-both of which are toxic to the human body. Casein also contains a high quantity of alpha Casein-a protein found only in animal milk, which is not easily digestible by humans. Casein has also been found to increase blood cholesterol in humans.

Casein does have the advantage of being more slowly absorbed. This is mostly because casein actually clots in your stomach and delay gastric emptying. This is good if you can't eat often, and for overnight when you sleep. However in my opinion there are many better places to get casein than in protein and meal replacement powders. Yogurt, cottage cheese and non-fat cheeses are not only more palatable but more reliable. Casein powder is never fresher than milk, yogurt, and cheese. Why pay a lot of money on a supplement that has casein and milk proteins, when there are cheaper sources?

Back to TC Luoma's statement. I agree to a point, but it's a very BIG point. What he's forgetting is that feeding a natural bodybuilder an entire year on casein could result in less muscle growth than a natural bodybuilder who uses whey because of a couple of key factors.

One key factor is whey's ability to reduce free radical damage in the body.

Glutathione is arguably the most important water-soluble anti-oxidant found in the body. It's actually a naturally occurring amino acid tripeptide (made up of L-cysteine, L-glutamic acid, and glycine). Gutathione protects muscle cells against oxygen and it's metabolites, notably free radicals, and carcinogens. Casein has been shown in tests to not rise Glutathione levels anything above normal. Keeping free radical damage to a minimum helps to keep the body in an anabolic state. Whey is actually anti-catabolic.

In other tests, whey was shown to increase immune response 5 times greater than that of casein. Keeping healthy is a key factor in any bodybuilder's growth.

However the kicker is that whey has been shown in tests to increase IGF-1. Insulin like growth factor (IGF-1), is the growth factor that is released during the destruction of GH in the liver, and is the real cause of the growth associated with GH. Studies indicate that the quality of protein in the diet is proportional to levels of IGF-1. High levels of HIGH quality protein increase IGF-1. With casein being relatively low (right down there with soy) in Biological Value, you can hypothesize that casein will have little or no effect on raising IGF-1 levels.

More studies show that whey caused an increase in protein synthesis by 68% with 30g, while in the same study; casein only increased protein synthesis by 31% with 43g of casein. That's a significant difference even if dosages where the same, however the casein dosage was even higher, further showing it's relative ineffectiveness.

Whey also improves zinc retention better than Casein. Any of you familiar with the ZMA craze as of late will know that keeping zinc levels up also keeps testosterone levels up. There are few doubts as to testosterone's ability to build more muscle.

This doesn't mean you should cut out casein altogether. I would recommend eating about 30-40g of it right before bed. Other than that? Forget about it.

I think by now it's pretty obvious to you the advantages of whey protein over casein. TC's bodybuilder would make gains of course; there is no disputing that casein is good enough to build muscle, however it's not the best choice, and you should always go for the best choice.

In the end, "best" wins out over "good enough" every time.


Meinertz H et al. Soy protein and casein in cholesterol-enriched diets: effects on plasma lipoproteins in normolipidemic subjects. Am J Clin Nutr, 1989;50(4):786-793.

Mahé S et al. Digestion of bovine milk proteins in patients with high jejunostomy. Am J Clin Nutr, 1991;54:534-538.

Renner E. Milk and Dairy Products in Human Nutrition. Munich, Germany, 1983, p. 104.

Boirie Y et al. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci, 1997;94:14930-14935.

Rehner G et al. Effect of proteins on availability of zinc. I. Gastrointestinal transit time of casein and whey protein and zinc absorption in weaned rats. Z Ernahrungswiss, 1985;24(4):245-55.

Dan Duchaine. BodyOpus: Militant fat loss and body recomposition" Nevada: Xipe Press 1996.

William D. Brink "Priming the Anabolic Environment" BTS Publishing: Boston, MA 1995.

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