Question

Which of the following nutrients show a dramatic increase in absorption during pregnancy?

• A. Salt and sugar
• B. Protein and fat
• C. Calcium and iron
• D. Thiamin and ascorbic acid

Hint:

To protect maternal bones and blood oxygen levels, hormonal adaptations during pregnancy increase the intestinal absorption efficiency of calcium and iron.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to identify which pair of dietary nutrients experiences a significant, physiological increase in maternal intestinal absorption efficiency during pregnancy to meet maternal and fetal developmental requirements.

Step 2: Detailed Explanation:

• Maternal Adaptations: Pregnancy triggers homeostatic adaptations in the maternal gastrointestinal tract to maximize the uptake of critical minerals needed for fetal skeletal and vascular development.

• Calcium Absorption:

• Calcium is essential for the development of the fetal skeleton.

• To meet this demand without depleting maternal bone mineral density, maternal intestinal calcium absorption efficiency nearly doubles during pregnancy, driven by hormonal changes (increased active vitamin D, $1,25(\text{OH})_2\text{D}_3$).

• Iron Absorption:

• Iron is required to support maternal erythropoiesis (blood volume expansion) and fetal placental growth.

• Maternal iron absorption efficiency increases during the second and third trimesters, driven by low systemic hepcidin levels, allowing the body to absorb a higher percentage of dietary iron.

• Other Options: Macronutrients like proteins, fats, salt, and water-soluble vitamins do not show the same physiological increases in active absorption efficiency compared to these two critical minerals.

Step 3: Final Answer:
The intestinal absorption of calcium and iron increases significantly during pregnancy to support fetal development, corresponding to option (C).