The Claim

In older men, 20 days of high protein intake (greater than 2.1 g/kg lean body mass per day) increases direct arterial-to-venous shunting of amino acids by an average of 2.9 μmol/min compared to recommended protein intake (1.1 g/kg lean body mass per day), without increasing muscle protein synthesis.

Source: Postprandial muscle protein synthesis rate is unaffected by 20-day habituation to a high protein intake: a randomized controlled, crossover trial

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
72score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

How it works
1 study reviewed
In plain English

In older men, consuming more than 2.1 grams of protein per kilogram of lean body mass for 20 days increases the amount of amino acids diverted directly from arteries to veins by 2.9 micromoles per minute compared to consuming 1.1 grams per kilogram, but this change does not result in higher muscle protein synthesis.

See the scientific wording

In older men, 20 days of high protein intake (greater than 2.1 g/kg lean body mass per day) increases the direct arterial-to-venous shunting of amino acids by an average of 2.9 μmol/min compared to recommended protein intake (1.1 g/kg lean body mass per day), suggesting a shift in amino acid handling that does not translate to increased muscle protein synthesis.

Why this might work

When older men consume very high amounts of protein, their liver and muscles take up more amino acids from the blood, but instead of using them to build muscle, the amino acids are diverted directly from arteries to veins without being incorporated into muscle tissue.

Supported mechanismbased on 1 study

What the research says

1 study

  1. Study: Postprandial muscle protein synthesis rate is unaffected by 20-day habituation to a high protein intake: a randomized controlled, crossover trial

    When older men ate a lot more protein for 20 days, their bodies sent more amino acids straight from blood to veins without using them to build muscle — just like the claim says. The extra protein didn’t help build more muscle, but it did change how the body moved amino acids around.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

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