They are called essential. If these eight are not supplied in the proper amounts, or there is some pathway block in the protein synthesis, essential enzymes cannot be manufactured. For example, L-tyrosine is an amino acid and needs iodine to become thyroxin, the thyroid hormone. They are Interdependent. Once the machinery is operating smoothly, these amino acid supplements can be discontinued and sensible eating habits will maintain the physiology.
Continued use is fine, but can be expensive.
They are utilized best if taken on an empty stomach. Threonine is important in fat metabolism, and is low in those on a vegetarian diet. People who have little are often irritable, hard to get along with. L-Glutamic Acid detoxifies ammonia, which is common in candida sufferers. It aids brain metabolism, often controls symptoms of hypoglycemia, and, thus, is a standby in the treatment of alcoholism.