The amino acid that is deficient in wheat is?

Appeared in: SCTIMST Staff Nurse - 2016

Explanation

Proteins are made of amino acids; those the body cannot make are called 'essential' and must come from food.
The 'limiting amino acid' is the essential amino acid present in the lowest amount in a food, which restricts protein synthesis.
Wheat is a cereal grain, and the protein in most cereals is characteristically low in the essential amino acid Lysine.
Because Lysine is the most deficient essential amino acid in wheat relative to human needs, it is considered the limiting amino acid.

Option A: Leucine is a branched-chain amino acid that is generally found in adequate amounts in wheat and other cereals.
Option B: Methionine is the primary limiting amino acid in pulses and legumes, not in cereals like wheat. Grains are a relatively good source of methionine.
Option D: Cystine is a sulfur-containing amino acid, and its requirement is linked to methionine. It is typically limiting in pulses along with methionine, not in cereals.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Limiting amino acids and protein quality as background academic context rather than a clinical decision trigger.
Understanding limiting amino acids is crucial for planning balanced diets, especially for individuals on vegetarian or vegan diets who do not consume complete animal proteins.
In the Indian context, the traditional combination of dal (pulses) and roti/rice (cereals) is a practical application of protein complementation that ensures a balanced intake of all essential amino acids.
A diet severely deficient in essential amino acids can lead to protein-energy malnutrition, such as Kwashiorkor, characterized by edema, poor growth, and muscle wasting. Nurses play a key role in nutritional assessment and education to prevent such conditions.

How to Approach the Question

First, identify the key terms in the question: 'amino acid', 'deficient', and 'wheat'.
Recognize that 'wheat' is a type of cereal grain.
Recall the basic nutritional principle regarding the protein quality of major food groups.
Remember the key pairing: Cereals are limiting in Lysine, and Pulses/Legumes are limiting in Methionine.
Apply this rule to the question. Since the food is wheat (a cereal), the deficient amino acid is Lysine.
Evaluate the options to confirm your answer and eliminate the distractors based on this rule.

Concept Tested & Keywords

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E6 Nutrition Monika Sharma 3e p. 87-89

Practise the full SCTIMST Staff Nurse - 2016

Attempt every question from this paper in a timed mock, then review the full solution for each one.