How many of the 20 amino acids used to build human proteins are considered essential in our diet?

• A. 6.
• B. 9.
• C. 11.
• D. 15.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of essential amino acids. Essential amino acids are those that cannot be synthesized by the human body and must be obtained through the diet.
2. Step 2: Recall that there are 20 amino acids used to build human proteins. Out of these, some are classified as essential because the body cannot produce them.
3. Step 3: Identify the number of essential amino acids. Research and nutritional science confirm that there are 9 essential amino acids required in the human diet.
4. Step 4: Review the list of essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
5. Step 5: Compare the given options (6, 9, 11, 15) and select the correct number of essential amino acids, which is 9.