The answer is not without malnutrition.
Amino acids are the substances required for the body's metabolic synthesis. They can provide raw materials for the synthesis of proteins including enzymes and antibodies, as well as many cytokines with immune functions. They can also be converted into carbohydrates and fats, or consumed by metabolism to generate energy.
For healthy people, we have normal digestion and absorption functions. Many of the foods we eat contain protein or amino acids. Protein can be digested into amino acids for reabsorption. Non-essential amino acids can also be synthesized in the human body. Most of us healthy people have abundant amino acids in the body to maintain physiological functions including immune function.
For people who have obvious protein malnutrition and cannot eat normally, injecting amino acids to supplement the amino acids required in the body can provide raw materials for maintaining normal physiological functions, including the operation of the immune system, and may be helpful for immunity.
Therefore, for people who are severely malnourished and cannot eat normally for a long time due to various reasons, doctors can infuse nutrients including amino acids to supplement or maintain nutrition after evaluating the condition, so as to maintain physiological functions including immunity.
For people who have no nutritional problems, they do not need it. Injection of amino acids will not improve immunity, but may increase the nutritional burden, and may also cause adverse reactions such as infusion reactions.