How many amino acids must be available in diet?

Question

Accepted Answer

The correct option is (1):
The correct option is (1): The foundational principle of human nutrition dictates that our body requires 20 standard amino acids to construct all the proteins necessary for life. These are categorized based on whether the body can synthesize them itself or not. The nine amino acids, known as Essential Amino Acids (EAAs), are those that the human body cannot synthesize internally at a rate sufficient to support growth and repair. Therefore, it is essential that these nine—Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine—be consistently included in the daily diet through high-quality protein sources. Adequate intake of these nine EAAs is non-negotiable for muscle synthesis, hormone production, and overall cellular maintenance, which is why they are a vital component of nutritional science.

The incorrect option is (2): 23 Amino Acid is an incorrect number. While the total number of amino acids involved in human biology can be viewed as 20 standard amino acids, plus two special ones (Selenocysteine and Pyrrolysine), the number 23 is not the recognized total. More importantly, it does not represent the minimum required for dietary consumption. This option is too high, covering amino acids that the body is fully capable of producing on its own.

The incorrect option is (3): 12 Amino Acid is incorrect because it does not represent a recognized physiological or nutritional category. In the standard set of 20 amino acids, if 9 are essential, the remaining 11 are generally considered non-essential (synthesizable by the body). The number 12 may arise from confusion with the non-essential or conditionally essential amino acids, but the correct, fixed count of amino acids that *must* be available in the diet is nine.

The incorrect option is (4): 17 Amino Acid is also an incorrect value. This number is arbitrary and does not align with the scientifically accepted total of 20 standard amino acids, nor does it represent the critical subset of essential amino acids that must be obtained from food. Dietary protein quality is defined by the presence of all nine essential amino acids, making the number 17 substantially higher than the actual requirement.