Question

Which of the following organs will be severely affected by deprivation of lactose in the diet of an infant?

• A. Liver
• B. Kidney
• C. Pancreas
• D. Brain

Hint:

Nutritional Role of Lactose: Hydrolysis yields D-GALACTOSE $\rightarrow$ Essential for synthesising Galactocerebrosides required for BRAIN MYELINATION in infants.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Pediatric neurodevelopmental biochemistry: intestinal hydrolysis of lactose yields D-galactose, an obligate structural precursor for synthesizing galactolipids (cerebrosides and gangliosides) required for myelin sheath formation and neonatal cerebral neurodevelopment.
Key Formula or Approach:
\[ \text{Lactose} \xrightarrow{\text{Lactase}} \text{D-Glucose} + \mathbf{D\text{-Galactose}} \xrightarrow{\text{UDP-Galactose}} \mathbf{Galactocerebrosides \text{ (Brain Myelination \& Neural Growth)}} \]

Step 2: Detailed Explanation:
In human neonatal nutrition and brain neurodevelopment:
- Lactose ($pprox 7.0\%$ in human breast milk) is the exclusive carbohydrate source for infants:
1. Intestinal lactase hydrolyzes lactose into D-glucose (immediate cellular energy) and D-Galactose.
2. Galactose is specifically utilized in the central nervous system to biosynthesize Galactocerebrosides (Galactosylceramides) and Gangliosides—the foundational lipid-glycoprotein structural building blocks forming the myelin sheath around cranial nerve axons and cerebral cortical membranes.
3. Depriving an infant of lactose during the critical neonatal brain-growth spurt ($0 - 2\text{ years}$) severely impairs myelination, cerebral membrane architecture, and cognitive neural maturation, making the Brain (D) the most severely affected organ.

Step 3: Final Answer:
Therefore, the organ severely affected by lactose deprivation is Brain, corresponding to option (D).