Depends. And some supplements can enhance assimilation / utilization.
Originally Posted by muratkolukirik
From Bodybuildings Biggest Protein Myths Debunked (Layne Norton)
Myth: "You can only absorb 'X' grams of protein in one meal."
The real deal: Not only is this myth not rooted in any kind of fact, it's actually a misnomer in and of itself. Absorption refers to the amount of a certain substance that makes it into circulation (blood) from the digestive tract. The body will absorb a good portion of the protein you eat regardless of the amount of protein in the meal (though there's a limit to the percentage absorbed and it will vary between protein sources). What this myth actually refers to is protein/amino acid utilization. Specifically, what's the maximum amount of protein at a meal that will be used for muscle-building processes, and at what point does the amount of protein become excessive and the extra amino acids burned for energy rather than retained? At this point, researchers have no good answer to this question, but the answer probably depends on many various factors, including but not limited to:
- lean body mass
- length of time since last protein-containing meal
- amount of protein at previous meal
- type of protein source
- training state (Post-workout? Pre-workout? Resting?)
- total calories in the meal
- caloric balance
Although there's no definitive answer as to the maximum amount of protein that's beneficial at a meal, there's some research out there that is mildly helpful. Leucine, the amino acid that's an anabolic component of protein1 and is responsible for stimulating protein synthesis, was administered at different doses in rats to see what dose elicited the maximum protein synthetic response.2 The researchers found that the maximum beneficial dose of leucine was achieved at 0.68 grams of leucine per kilogram of bodyweight. This equates to about 62 grams of leucine in a 200-pound individual, which is an unrealistic amount to get from whole food. There are many problems with applying the absolute numbers from this study to a whole food meal in humans because of the differences in protein metabolism between rats and humans. In order to determine what level of leucine at a meal elicits the greatest anabolic response for the longest period of time more human studies will be required, but the research is moving in the right direction. While there's most definitely a maximum beneficial protein intake at a meal, no studies have directly addressed the subject and the number is likely to be influenced by various factors. So, pay no attention to Joe Dumbbell who says you can only absorb (insert gram amount) of protein at a meal, because he has no clue.