7️⃣ Nutrition

Question 1

Define malnutrition and its broad categories.

Answer 1

Malnutrition = inadequate protein/calorie intake or absorption; includes under-nutrition (deficiency), over-nutrition (obesity), eating disorders, and micronutrient deficiencies.

Question 2

Describe vitamin D metabolism and deficiency outcomes.

Answer 2

Vitamin D from diet/skin → liver 25-hydroxylation → kidney 1α-hydroxylation → 1,25(OH)₂D; deficiency causes rickets in children and osteomalacia in adults.

Question 3

Describe vitamin A metabolism and deficiency outcomes.

Answer 3

Retinol from diet → oxidized to retinoic acid; functions in vision, cell differentiation, gut epithelium; deficiency → epithelial metaplasia, keratin debris (stone) formation, ↑ cancer risk.

Question 4

Describe vitamin C function and deficiency (scurvy).

Answer 4

Cofactor for prolyl/lysyl hydroxylases in collagen synthesis; antioxidant; deficiency → unstable collagen, bleeding gums, skin/joint hemorrhages, poor wound healing.

Question 5

What are health effects of protein-calorie malnutrition?

Answer 5

Generalized weakness, wasting.

Question 6

List health effects of key vitamin deficiencies.

Answer 6

D: rickets/osteomalacia; A: epithelial metaplasia, cancer risk; C: scurvy (bleeding, poor healing).

Question 7

Explain how cancer risk is influenced by diet.

Answer 7

Carcinogens in food (aflatoxins → p53 mutations, nitrosamines), low protective factors (fiber), Neu5Gc incorporation (chronic inflammation, ROS → atherosclerosis, cancer).

Question 8

What causes obesity in terms of energy balance?

Answer 8

Chronic caloric intake > expenditure due to dysregulated homeostatic mechanisms.

Question 9

Describe normal CNS-gut-endocrine regulation of energy.

Answer 9

Hypothalamus integrates adiposity (leptin), pancreatic (insulin), and gut hormone (ghrelin, PYY) signals to adjust appetite, metabolism, and energy expenditure.

Question 10

What mechanisms are disrupted in obesity?

Answer 10

Blunted satiety/hunger signaling, increased weight “set point,” insulin/leptin resistance, altered gut hormone responses, and breakdown of CNS-gut feedback loops.

Question 11

List diseases caused or worsened by obesity.

Answer 11

Type 2 diabetes, metabolic syndrome, cardiovascular diseases, certain cancers, endocrine dysfunction, and impaired energy regulation with resistance to weight-loss signals.