Animal study: L-citrulline supplementation accelerates healing of broken bones
People who have broken a bone may promote their healing process by supplementing with the amino acid L-citrulline. This is suggested by an animal study that Dutch researchers at Maastricht University Medical Center published in European Cells and Materials.Study
The researchers experimented with old female mice, surgically sawing the bone in their hind legs into two pieces, and then re-joining them with screws. In doing so, however, the researchers left a little space between the two parts of the bone, so the bone had to form new bone tissue.

The researchers gave the test animals 4.6-5 grams of arginine or citrulline per kilogram of body weight daily. These were the experimental groups.If the mice had been human adults, they would have received about 30 grams of citrulline daily. That's a lot - and maybe too much. In most human studies, subjects are given only 2-8 grams of citrulline per day.
Mice in a control group received no additional amino acids.
The researchers scanned the bones 14 days after the procedure. The scans showed that supplementation with the amino acids - especially supplementation with citrulline - accelerated the healing of bone tissue.

The mice also lost less weight after surgery due to amino acid supplementation. This may implicate that citrulline, and to a lesser extent arginine, enhanced the animals' entire health during the healing process.

The researchers believe that citrulline, and to a lesser extent arginine, accelerates bone fracture healing by converting citrulline into building blocks of collagen in bone tissue.

In addition, citrulline may also stimulate the construction of new blood vessels, so that new bone tissues can be supplied with more oxygen and nutrients.
Eur Cell Mater. 2020 Mar 20;39:183-92.