Q.13 Patients with Galactosemia are advised not to take dairy products because
1. they have defective B-galactosidase and cannot digest lactose in dairy products
2. they cannot metabolize galactose digestion product of lactose
3. they cannot digest the fats present in dairy products
4. they cannot digest the proteins present in dairy products
Galactosemia requires avoiding dairy products due to the inability to process galactose, a component of lactose found in milk. The correct answer is option 2, as patients cannot metabolize this sugar breakdown product.
Correct Answer
Option 2: They cannot metabolize galactose digestion product of lactose.
Lactose in dairy breaks down into glucose and galactose via lactase. In galactosemia (often classic type), deficient galactose-1-phosphate uridylyltransferase (GALT) causes toxic buildup of galactose-1-phosphate and galactitol, leading to liver damage, cataracts, and sepsis. A lactose-free diet prevents these effects.
Option Breakdown
| Option | Statement | Correct/Incorrect | Explanation |
|---|---|---|---|
| 1 | Defective B-galactosidase and cannot digest lactose | Incorrect | B-galactosidase (lactase) digests lactose; its defect causes lactose intolerance, not galactosemia, which affects post-digestion galactose metabolism. |
| 2 | Cannot metabolize galactose digestion product of lactose | Correct | Galactose from lactose accumulates toxically due to GALT deficiency; dairy avoidance eliminates the source. |
| 3 | Cannot digest the fats present in dairy products | Incorrect | Fat digestion issues (e.g., lipase deficiency) are unrelated; galactosemia targets carbohydrate metabolism. |
| 4 | Cannot digest the proteins present in dairy products | Incorrect | Proteins like casein are irrelevant; the problem is sugar metabolism, not proteolysis. |
Galactosemia Pathway Basics
Lactose → glucose + galactose (lactase). Galactose enters Leloir pathway: galactokinase → gal-1-P → GALT → UDP-glucose. Blockage causes toxicity, resolved by galactose restriction.
