Nutrition and Metabolism — MCQs

Nutrition and Metabolism Indian Medical PG Practice Questions and MCQs

Question 321: Which food item contains the highest protein content among the following options?

A. Egg
B. Soyabean (Correct Answer)
C. Rice
D. Wheat

Explanation: ***Soyabean*** - **Soybeans** are considered a complete protein, containing all **nine essential amino acids** required for human health. - They typically contain about **36-40 grams of protein per 100 grams** (dried/raw), making them one of the richest plant-based protein sources. - This is **significantly higher** than any of the other options listed. *Egg* - A **large egg** contains approximately **6 grams of high-quality protein**, including all essential amino acids. - Per 100 grams, eggs provide about **12-13 grams of protein** - excellent quality but much lower quantity than soybeans. *Rice* - **Rice**, particularly white rice, is primarily a source of **carbohydrates** and contains relatively low protein content. - Raw white rice provides about **7 grams of protein per 100 grams** (uncooked), making it the lowest protein source among these options. *Wheat* - **Wheat** is a grain rich in carbohydrates and also contains a moderate amount of protein, primarily **gluten**. - Whole wheat grain contains approximately **13-14 grams of protein per 100 grams**, which is comparable to eggs but significantly less than soybeans.

Question 322: Calcium absorption is hampered by

A. Protein
B. Lactose
C. Acid
D. Phytates (Correct Answer)

Explanation: ***Phytates*** - **Phytates** (phytic acid) found in whole grains, legumes, nuts, and seeds bind to calcium, forming an insoluble complex that significantly **reduces its absorption** in the intestines. - This binding prevents the free calcium ions from crossing the intestinal wall into the bloodstream. *Protein* - **Protein** generally *enhances* calcium absorption, especially when consumed in moderate amounts, as some amino acids can form soluble calcium complexes. - However, very high protein intake, particularly from animal sources, *may* slightly increase urinary calcium excretion in the long term, but it does not directly hamper intestinal absorption. *Lactose* - **Lactose**, a sugar found in milk, is known to *enhance* calcium absorption. - It does so by creating a more acidic environment in the small intestine and by forming soluble complexes with calcium, making it more bioavailable. *Acid* - **Stomach acid** (hydrochloric acid) is crucial for calcium absorption as it helps to solubilize calcium salts from food. - A *reduced* acidic environment, such as from antacid use or certain medical conditions, would hamper calcium absorption, but acid itself is beneficial.

Question 323: All of the following are required more during lactation as compared to pregnancy, except ?

A. Niacin
B. Energy
C. Iron (Correct Answer)
D. Vitamin A

Explanation: ***Iron*** - **Iron requirements are significantly higher during pregnancy** (~27 mg/day) due to the expansion of maternal red blood cell mass, fetal development, and placental iron needs. - During lactation, iron requirement decreases to **~9-10 mg/day**, lower than in pregnancy, as **lactational amenorrhea** (absence of menstruation) reduces iron loss. - This represents the **most significant decrease** in requirement from pregnancy to lactation among the listed nutrients. *Vitamin A* - The **recommended daily allowance (RDA) for Vitamin A is higher during lactation** (~1300 μg/day) compared to pregnancy (~800 μg/day). - This increased requirement ensures **adequate transfer to breast milk** to support infant's **vision development and immune function**. *Niacin* - **Niacin requirements during lactation** (~17 mg/day) are **similar to pregnancy** (~18 mg/day). - While lactation involves increased metabolic demands, niacin requirements do not show a marked increase compared to pregnancy, unlike Vitamin A and Energy. - This option is less clearly "required more" during lactation. *Energy* - **Energy requirements are significantly higher during lactation** to fuel milk production, which is energetically demanding. - A lactating woman typically needs an **additional 500 kcal/day**, compared to ~300 kcal/day in the 2nd/3rd trimester of pregnancy.

Question 324: Which nut has the highest protein content among the following options?

A. Walnut
B. Coconut
C. Groundnut (Correct Answer)
D. Almond

Explanation: ***Groundnut*** - **Groundnuts** (peanuts) contain approximately **26 grams of protein per 100 grams**, which is the highest among the given options. - While botanically classified as legumes, groundnuts are commonly grouped with nuts in nutritional contexts. - They are also rich in **healthy fats**, **fiber**, and various **B vitamins**. *Almond* - **Almonds** contain about **21 grams of protein per 100 grams**, making them the second highest in protein content among the options. - They are excellent sources of **vitamin E**, **magnesium**, and **healthy monounsaturated fats**. *Walnut* - **Walnuts** contain approximately **15 grams of protein per 100 grams**, which is lower than both groundnuts and almonds. - They are notably rich in **omega-3 fatty acids** (alpha-linolenic acid). *Coconut* - **Coconut flesh** has relatively low protein content, around **3.3 grams per 100 grams**. - It is primarily known for its high content of **medium-chain triglycerides** and **saturated fats**.

Question 325: Clinical effect of vitamin D is reduced by ?

A. Simultaneous ingestion of lactose
B. Simultaneous ingestion of phytates (Correct Answer)
C. None of the options
D. Acidic environment

Explanation: ***Simultaneous ingestion of phytates*** - **Phytates (phytic acid)** found in whole grains, nuts, seeds, and legumes can **reduce the clinical effect of vitamin D** through multiple mechanisms - Phytates **chelate calcium** and form insoluble calcium-phytate complexes, reducing calcium absorption - Since **vitamin D and calcium metabolism are closely linked**, impaired calcium absorption indirectly reduces vitamin D efficacy - Phytates can also **directly bind to vitamin D** in the gastrointestinal tract, reducing its bioavailability - Studies show that **high phytate intake increases vitamin D requirements** and can impair vitamin D status *Simultaneous ingestion of lactose* - Lactose does **not reduce** vitamin D absorption or efficacy - In fact, **dairy products are commonly fortified** with vitamin D, and the presence of lactose does not interfere with its beneficial effects - Lactose may actually **enhance calcium absorption**, which works synergistically with vitamin D *Acidic environment* - Vitamin D is a **fat-soluble vitamin** absorbed primarily in the small intestine - An acidic environment (stomach acid) is **not known to inhibit** vitamin D absorption - The absorption process occurs in the **alkaline environment of the small intestine** where fat-soluble vitamins are absorbed with dietary fats *None of the options* - This is **incorrect** as phytates do reduce the clinical effect of vitamin D through calcium chelation and direct binding mechanisms

Question 326: Which is not a dietary fiber ?

A. Lignin
B. Pectin
C. Cellulose
D. Lactulose (Correct Answer)

Explanation: ***Lactulose*** - **Lactulose is NOT a dietary fiber** - it is a synthetic disaccharide used pharmaceutically as an osmotic laxative and for treating hepatic encephalopathy. - Unlike true dietary fibers, lactulose is a manufactured drug, not a naturally occurring food component. - While it is fermented by colonic bacteria (similar to fiber), it does not meet the definition of dietary fiber. *Lignin* - Lignin is a complex aromatic polymer that provides structural support to plant cell walls. - It is classified as a non-polysaccharide dietary fiber that is largely indigestible by human enzymes. - Contributes to fecal bulk and is considered an insoluble fiber. *Pectin* - Pectin is a soluble dietary fiber found naturally in fruits, particularly in apple peels and citrus fruits. - Forms a gel when mixed with water, slowing gastric emptying and aiding digestion. - Beneficial for gut health and blood glucose regulation. *Cellulose* - Cellulose is the most abundant dietary fiber and a major structural component of plant cell walls. - An insoluble fiber composed of β-1,4-linked glucose polymers that cannot be digested by human enzymes. - Contributes to stool bulk and promotes regular bowel movements.

Question 327: In which of the following conditions is protein catabolism MOST increased?

A. Burns (Correct Answer)
B. Surgery
C. Starvation
D. Fever

Explanation: ***Burns*** - Severe burns lead to a profound **hypermetabolic state** with the highest increase in **protein catabolism** among all the options listed. - The extensive tissue damage triggers massive breakdown of muscle protein to provide amino acids for **wound healing**, **acute phase protein synthesis**, and **immune response**. - Burns can increase metabolic rate by **100-200%**, with protein catabolism far exceeding that of other stress conditions. *Starvation* - While starvation initially increases protein catabolism, the body adapts within days by shifting towards **ketone body utilization** to spare protein. - After adaptation, protein breakdown decreases to **20-30 grams per day** to preserve lean body mass. - The goal is survival through metabolic adaptation, not tissue repair. *Surgery* - Major surgery induces a **stress response** that increases protein catabolism, but it is typically less severe and shorter-lived than burns. - The degree of catabolism is proportional to the **magnitude of surgical trauma** and usually resolves within days. - Protein catabolism increases by **50-75%** in major surgery compared to **100-200%** in severe burns. *Fever* - Fever increases basal metabolic rate by approximately **13% per degree Celsius** rise in body temperature. - While metabolism is elevated, protein catabolism is **modest** compared to the massive tissue destruction and repair demands of severe burns. - The increase is primarily in energy expenditure, not protein breakdown.

Question 328: Which of the following plant components is not fermented by gastrointestinal microorganisms?

A. Lignin (Correct Answer)
B. Cellulose
C. Hemicellulose
D. Pectin

Explanation: ***Lignin*** - **Lignin** is a complex polymer found in plant cell walls that is highly resistant to degradation by digestive enzymes and microbial fermentation in the gastrointestinal tract. - Its complex, cross-linked structure makes it **non-fermentable** by the microorganisms typically present in the human gut. *Cellulose* - **Cellulose** is a major component of plant cell walls and is a type of dietary fiber that can be fermented by certain gut bacteria. - While humans lack the enzymes to digest cellulose, colonic microorganisms possess cellulases that break it down into **short-chain fatty acids (SCFAs)**. *Hemicellulose* - **Hemicellulose** is a diverse group of plant polysaccharides that are a significant source of fermentable fiber for gut microbiota. - It is readily broken down by gastrointestinal bacteria into **SCFAs** and gases, contributing to colonic health. *Pectin* - **Pectin** is a soluble dietary fiber found in fruits and vegetables, known for its gel-forming properties. - It is highly fermentable by gut microorganisms, leading to the production of **SCFAs** like butyrate, propionate, and acetate.

Question 329: Selenium deficiency is seen in -

A. Keshan disease (Correct Answer)
B. Wilson disease
C. Acrodermatitis enteropathica
D. None of the options

Explanation: ***Keshan disease*** - **Keshan disease** is a form of **cardiomyopathy** caused by **selenium deficiency**, particularly prevalent in regions with selenium-poor soil. - It presents with **heart failure**, arrhythmias, and cardiac enlargement. *Wilson disease* - **Wilson disease** is a disorder of **copper metabolism**, leading to excessive copper accumulation in organs, primarily the liver and brain. - It is not related to selenium deficiency. *Acrodermatitis enteropathica* - **Acrodermatitis enteropathica** is a genetic disorder of **zinc deficiency**, characterized by dermatitis, diarrhea, and alopecia. - It does not involve selenium deficiency. *None of the options* - This option is incorrect because Keshan disease is directly linked to selenium deficiency.

Question 330: What is the recommended daily calcium intake for adult non-pregnant females?

A. 1000 mg (Correct Answer)
B. 1200 mg
C. 600 mg
D. 800 mg

Explanation: ***1000 mg*** - The recommended daily calcium intake for adult non-pregnant females (ages 19-50) is **1000 mg** according to **WHO and international guidelines** (US RDA/NIH) to maintain bone health and prevent osteoporosis. - This is the **standard recommendation** used in most medical textbooks and international nutritional guidelines. - Adequate calcium intake supports various bodily functions, including **nerve transmission**, **muscle contraction**, and **hormone secretion**. *1200 mg* - While 1200 mg is the recommended intake for **older women (above 50-70 years)** or during **pregnancy/lactation** per some guidelines, it is generally higher than necessary for non-pregnant adult females aged 19-50. - While not harmful, this higher dose is not specifically indicated for the general non-pregnant adult female population. *600 mg* - This amount of calcium is **lower than the internationally recommended daily allowance** for adult women (though it aligns with some regional guidelines like ICMR for sedentary women). - For optimal bone health and prevention of osteoporosis, **1000 mg is the widely accepted standard** in medical education. *800 mg* - This value is **below the internationally recommended daily intake** for adult non-pregnant females, which could lead to long-term calcium deficiency. - Insufficient calcium intake can increase the risk of conditions like **osteopenia** and **osteoporosis**.

Practice by Chapter

Macronutrients and Energy Requirements

Practice Questions

Protein Quality and Nitrogen Balance

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Essential Amino Acids and Proteins

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Essential Fatty Acids and Lipids

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Dietary Fiber and Complex Carbohydrates

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Glycemic Index and Glycemic Load

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Micronutrients: Vitamins and Minerals

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Trace Elements and Metabolism

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Malnutrition: Biochemical Consequences

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Dietary Antioxidants

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Functional Foods and Nutraceuticals

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Dietary Guidelines and Recommendations

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