Both whey and casein are derived from milk, with casein making up 80 percent and whey 20 percent. While whey protein may be more suitable for quick recovery after a workout, past, present and emerging data support the notion that casein is the better choice later in the evening and at night.
A large body of emerging data also suggest that taking casein throughout the day is of great benefit as well, as it slowly releases valuable amino acids over a longer time period. That’s critical to helping the body maintain what researchers refer to as the amino acid pool.
The slow release occurs because casein, a milk protein, curdles in the stomach as it unites with various enzymes. It generally takes three to four hours for amino acids from casein to hit your bloodstream.
In a recent study conducted by French researchers at l’Université d’Auvergne Clermont-Ferrand I that compared whey to casein, subjects were given 30 grams of either whey or casein. After seven hours the researchers found that with casein there was a 31 percent drop in protein synthesis. There was also 27 percent less oxidation, or breakdown, of casein protein vs. whey, however, and that resulted in a more sustained period of nitrogen retention—which is critical to maintaining a state of anabolic equilibrium. Maintaining proper nitrogen balance is a key factor in muscle growth and development.
The final and most critical aspect of those numbers was a 34 percent decrease in muscle protein breakdown in subjects who got casein protein vs. those who got whey. The bottom line is that better nitrogen retention equates to better muscle growth and repair, and that’s music to any bodybuilder’s ears!
One last point: Like whey, casein is derived from milk. Casein is immediately collected after it curdles in the cheese-making process. When you purchase casein protein, make sure it isn’t listed as caseinate or calcium caseinate. Those forms are extracted before the curdling process and are actually a much lower grade of casein protein. Micellar casein is 100 percent casein protein and is a better choice. [Note: For a premium micellar casein-whey combo-array protein, see page 14 of the August 2010 issue of Iron Man.]