Considering all these effects together, glutamine may potentially retard some of the effects of aging by preserving muscle mass and reducing fat accumulation. Growth hormone helps build and strengthen muscles and clear acid from body fluids, but starting at age 30, its production declines. Although this is only an animal trial, the potential ability of glutamine supplements to reduce insulin resistance is exciting. Insulin resistance is now estimated to occur in half of all obese people and is considered a major risk factor for heart disease, high blood pressure and diabetes. While it is premature to jump from animal studies to conclusions about humans, the research so far may suggest a safe, nutritional way to adjust metabolism and look and feel healthy.
Different neurotransmitters can also influence perceptions of energy or fatigue.
Neurotransmitter production is thought to increase when the amino acids they are formed from are supplemented in the diet. If this is true for glutamine, nutritional strategies that replenish it may also boost perception of energy or help prevent mental fatigue. Two final points are important for the glutamine story. First, too much glutamine may be counterproductive. In humans, more than two grams is likely to result in less growth hormone production, less bicarbonate buffer, and probably no further energy benefit.