It is also possible that excessive protein intake can reduce calcium retention. Tryptophan is a precursor for 5 HT synthesis. It competes with the BCAAs to cross the blood-brain barrier. Prolonged exercise sees an increase in BCAA uptake by the muscles and a decrease in plasma concentrations. There is believed to be an increase in tryptophan entry to the brain and a greater risk of fatigue.
Experimental data are equivocal.
Glutamine - a fuel for lymphocytes and thus, function of the immune system. In a clinical setting, intravenous infusions of ornithine and arginine are used to test HgH 'reserve'. Well planned vegetarian diet - no problem Healthy. Typical deficiencies include inadequate protein and energy, reduced bioavailability of haem products, zinc, calcium and low intakes of B6, B12, riboflavin and Vit. Protein -often slightly higher than sedentary.