Protein Intake Ceiling Myth

There's this kind of worldwide belief that you can only digest ~30g of protein per meal, and any additional protein is just peed out and wasted.

This is BS--Here's why:

This so called "protein intake ceiling" derives from studies years ago that studied protein intake and urine nitrogen levels. The researchers basically observed increased Nitrogen losses in urine with increased protein intakes. From this, the researchers determined that the extra protein was wasted.

We now know that when you eat protein you don't use it directly--ingested protein breaks down into amino acids to create their own proteins. When you eat more protein, your body can afford to lose some. The proteins being replaced are damaged or oxidized proteins. This means protein synthesis AND protein breakdown are increased.

Going back to the old studies, this is why urinary nitrogen levels are increased. It doesn't reflect wasted proteins, it reflects an increase in the damaged or oxidized proteins that the new proteins replaced.

Also, your body does more than just use proteins to build muscle or make other proteins, it uses the nitrogen from amino acids to synthesize important non-protein molecules such as purines and pyrimidines. These are the building blocks for nucleic acids such as DNA and RNA.

Lastly, your small intestines store and absorb a ton of amino acids that your body will be ready to use when it has to. The overall protein usage from small intestine ingestion is around 91-95%. This is why people get the "protein sh*ts". Nitrogen has two pathways in the small intestines:

• Absorption

• Rectal excretion

The unabsorbed protein goes to the colon to get fermented by bacteria, then pooped out

Summary:

The idea that eating more than ~30g of protein results in wasted protein is incorrect. Your body will breakdown and find a way to use almost all the protein you eat