3-Methylhistidine

Urine and plasma levels of 3-methylhistidine can be higher with meat consumption.

Elevations have been seen in catabolism or fasting states.

3-methylhistidine may also be higher than normal if the diet or assimilation of folic acid and B-12 are insufficient.

3-methylhistidine is derived primarily from skeletal muscle, and to a lesser extent from skin. Elevated 3-methylhistidine may be indicative of an abnormal rate of catabolism of muscle protein in the body or an abnormal rate of turnover of muscle tissue. This may be a degenerative condition, or simply the result of very strenuous, prolonged exercise/athletic training.

3-methylhistidine is lower with low protein diets, or in vegetarian and vegan diets.

Both 1-methylhistidine and 3-methylhistidine are histidine metabolites which have been proposed as markers of meat intake. Note that some confusion exists in the literature regarding the numbering of atoms in the imidazole ring of histidine – 1 versus 3 – and thus, there is caution with interpretation and clinical significance of these two markers.

3-methylhistidine is a constituent of actin and myosin, the contractile proteins of skeletal muscles. Urinary excretion of 3-methylhistidine may be a result of muscle breakdown or consumption of meat fibers. Unlike 1-methylhistidine, 3-methylhistidine has been shown to increase in fasting states indicating catabolism of muscle tissue. Therefore, this marker is more variable with regards to animal protein consumption.