Question

First limiting essential amino acid in wheat and rice is ______

• A. Threonine
• B. Aspartic acid
• C. Lysine
• D. Cysteine

Hint:

Remember the classic limiting amino acid pairings:
- Cereals (Wheat, Rice, Corn) \( \rightarrow \) Limiting in Lysine.
- Legumes (Pulses, Soy) \( \rightarrow \) Limiting in Methionine.
Combining them in a meal provides a complete, balanced protein profile.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
An essential amino acid is one that cannot be synthesized by the body and must be supplied in the diet.
The "limiting amino acid" of a food protein is the essential amino acid present in the lowest amount relative to the body's requirements, limiting the overall nutritional value and protein synthesis.

Step 2: Detailed Explanation:
Cereal grains, such as wheat and rice, are the staple carbohydrate and protein sources for a large portion of the global population.
However, cereal proteins (such as gluten in wheat and oryzenin in rice) have a relatively poor amino acid profile compared to animal proteins.
The essential amino acid that is most deficient in both wheat and rice proteins is Lysine.
Because lysine is present in the lowest concentration relative to human nutritional requirements, it acts as the first limiting amino acid.
This nutritional deficit is often balanced in diets by combining cereals with legumes (such as pulses), which are rich in lysine but limiting in methionine.
Therefore, Lysine is the first limiting amino acid.

Step 3: Final Answer:
The first limiting essential amino acid in wheat and rice is Lysine.