Alanine

One of the most important glucogenic amino acids – it carries nitrogen from muscle to the liver (alanine-glucose cycle). During fasting it supplies the liver with starting material for making new glucose.

What alanine does in the body

Alanine is a building block of proteins and at the same time a means of transporting nitrogen. When the muscles break down amino acids – especially the branched-chain ones – they transfer their amino group to pyruvate, which is produced during sugar breakdown; the enzyme for this is alanine aminotransferase (ALT, formerly GPT), which needs vitamin B6. In this way nitrogen is packed into a non-toxic form that is easy to transport. Alanine travels via the blood to the liver: there the amino group is released again and excreted via the urea cycle, and from the remaining pyruvate the liver makes new glucose, which flows back to the muscles. This cycle, the glucose-alanine cycle, is particularly active during fasting and prolonged muscle work.

Low alanine – what happens in the body?

When there is little alanine in the blood, the muscles are releasing less of it – for example with low muscle mass, little protein in the diet or during long fasting periods in which the liver takes up and uses alanine rapidly. The liver then lacks part of the starting material for making new glucose; it has to rely more on other sources such as glycerol from fat tissue and lactate, and blood sugar is harder to maintain during long gaps between meals. Low alanine values have been observed in studies in children with recurrent low blood sugar during fasting.

High alanine – what happens in the body?

A lot of alanine is produced when more pyruvate accumulates in the cells than the mitochondria burn: some of it is then converted into lactate and some into alanine. This occurs with intense muscle work, with increased muscle breakdown under stress hormones and with impaired mitochondrial function, in which lactate and alanine rise together. Protein-rich meals also raise the value temporarily. The liver makes more glucose from the additional alanine. Raised values have been observed in studies with insulin resistance and fatty liver.

The interpretation is given in your report.