Glutamine

Glutamine is the most abundant free amino acid circulating in the blood as well as stored in the skeletal muscles. Glutamine is a diverse amino acid that is utilized in numerous vital functions. It is necessary for rapidly dividing cells, including those of the gut and immune system. Glutamine is used by the mitochondria in energy production and is a precursor to the neurotransmitter, glutamate. Glutamate sends signals between nerve cells, and under normal conditions it plays an important role in learning and memory

People who suffer from increased intestinal permeability (aka leaky gut) supplement with L-glutamine as it is thought to repair the intestinal tract. Leaky gut can drive fatigue and inflamation. Some CFS/ME sufferers have found some fatigue abatement by following the Leaky Gut diet.