Nutritional Science & Dietetics Flashcards

Which phase of digestion is stimulated by the sight and smell of food before eating begins?

Answer: Cephalic phase

The cephalic phase is the neurally mediated response to food cues (sight, smell, taste) that prepares the GI tract by stimulating saliva and gastric secretions before food arrives.

Pellagra is caused by deficiency of which vitamin, and what is its biochemical role?

Answer: Niacin; component of NAD+ and NADP+ for redox reactions

Niacin deficiency causes pellagra (dermatitis, diarrhea, dementia, death); niacin forms NAD+ and NADP+, which are essential electron carriers in energy metabolism.

What is the primary site of absorption for fat-soluble vitamins in the gastrointestinal tract?

Answer: Jejunum

Fat-soluble vitamins (A, D, E, K) are absorbed in the jejunum via micelle formation with bile salts, along with dietary fats.

A dietitian is counseling an older adult on calcium intake. Which combination of factors most impairs calcium absorption?

Answer: Low gastric acid (achlorhydria) and vitamin D deficiency

Calcium solubility and absorption requires adequate gastric acid and vitamin D (which induces calcium-binding proteins in intestinal cells); both are often deficient in older adults.

Which hormone primarily inhibits appetite by signaling satiety to the hypothalamus after a meal?

Answer: Leptin

Leptin, secreted by adipose tissue, signals the hypothalamus to suppress appetite and increase energy expenditure, reflecting long-term energy stores.

In a patient with chronic kidney disease (CKD), which dietary modification is typically required to prevent hyperkalemia?

Answer: Restrict dietary potassium to prevent dangerous elevations in serum levels

Impaired renal potassium excretion in CKD leads to hyperkalemia risk, so dietary potassium restriction is usually indicated to prevent cardiac arrhythmias.

The Maillard reaction in food processing primarily affects which nutrients?

Answer: Proteins and carbohydrates, reducing lysine bioavailability

The Maillard reaction between reducing sugars and amino acids (especially lysine) during heating creates browning compounds and reduces the bioavailability of lysine.