Which of the following is not excreted in breast milk?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Applied Nutrition & Dietetics

Medium

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Explanation

Iron is the correct answer because it is present in breast milk in very small quantities (approximately 0.4 to 1.5 mg/L).
This amount, while highly bioavailable, is insufficient to meet the needs of a growing infant after their initial iron stores (acquired in utero) are depleted around 4-6 months of age.
Compared to other minerals like calcium (330 mg/L) and phosphorus (150 mg/L), the concentration of iron is negligible.
The question uses the word "not" to identify the substance present in the least significant quantity among the options.

Option A: Zinc is excreted in breast milk and is vital for the infant's immune system and growth. Its concentration is highest in colostrum.
Option B: Phosphorus is excreted in significant amounts in breast milk (~150 mg/L). It is essential for bone mineralization, working alongside calcium.
Option D: Calcium is the most abundant mineral in breast milk (~330 mg/L) and is crucial for the development of the infant's bones and teeth.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Composition of minerals in human breast milk as background academic context rather than a clinical decision trigger.
A key nursing responsibility is educating new mothers about infant nutrition. This includes advising that exclusively breastfed, full-term infants need an iron source (like iron drops or iron-fortified cereals) starting at 4-6 months of age.
It is important to clarify that maternal iron supplementation does not significantly increase the iron content in breast milk. The transfer of iron into milk is tightly regulated.
What if the infant was born prematurely? Preterm infants have much lower fetal iron stores and higher growth demands, so they require iron supplementation much earlier, often starting within the first few weeks of life.

How to Approach the Question

First, identify the core of the question, which is about the composition of breast milk. The keyword "not" is critical; it implies you should look for the substance that is either absent or present in a negligible amount.
Recall the major minerals found in breast milk and their functions. All options listed (Zinc, Phosphorus, Iron, Calcium) are known to be present.
The next step is to compare the relative quantities of these minerals. Think about which ones are needed in large amounts for an infant's growth (like for bones) versus those needed in smaller amounts.
Calcium and Phosphorus are major components for skeletal growth, so they are present in high quantities.
Iron is famously low in breast milk, which is a major clinical point leading to supplementation recommendations.
Therefore, even though iron is technically 'excreted', its quantity is so low compared to the others that it is the correct answer for a 'which is not' type of question.

Concept Tested & Keywords

Concept Tested: Composition of minerals in human breast milk.
Stem keywords: excreted, breast milk
Lead-in keywords: not
Negative lead-in flag: Question is negatively framed, asking what is NOT excreted.

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