Nutrition and Metabolism Practice Questions

Q: What is the recommended daily protein intake for a healthy adult male?

1 gm/kg/day. ***1 gm/kg/day*** - The recommended daily protein intake for healthy adults is generally around **0.8 to 1.0 gram per kilogram of body weight** to maintain nitrogen balance and prevent deficiency. - This intake supports normal bodily functions, tissue repair, and muscle maintenance in non-athletic individuals. *0.5 gm/kg/day* - This amount is generally considered **below the optimal daily protein intake** for most healthy adults and may be insufficient to maintain proper nitrogen balance. - While it may prevent overt deficiency in some sedentary individuals, it does not support optimal muscle protein synthesis or recovery for active or moderately active adults. *1.5 gm/kg/day* - This level of protein intake is often recommended for individuals who are **highly active, engaged in resistance training**, or aiming for muscle gain. - While not harmful for most healthy individuals, it generally **exceeds the basic requirements** for a typical healthy adult male not involved in intense physical activity. *2 gm/kg/day* - This is a very high protein intake, often utilized by **competitive athletes, bodybuilders**, or individuals on specific weight loss programs. - While generally safe for healthy kidneys, it is **significantly higher than the recommended daily allowance** for the average healthy adult and not necessary for general health maintenance.

Q: Which of the following dietary fibers is most characteristically insoluble in water?

Lignin. ***Lignin*** - **Lignin** is a complex polymer found in plant cell walls, known for its **extreme insolubility** in water. - It provides structural rigidity to plants and is a non-carbohydrate component of **dietary fiber**. *Pectin* - **Pectin** is a type of soluble dietary fiber that forms a **gel-like substance** when mixed with water. - It is often used as a gelling agent in foods and is found in fruits like apples and citrus. *Hemicellulose* - **Hemicellulose** is a diverse group of polysaccharides; some forms are **soluble**, while others are **insoluble**, but it's generally more soluble than lignin. - Its solubility depends on its specific structure and sugar composition. *Cellulose* - **Cellulose** is an insoluble fiber, but it can absorb water and swell, contributing to **bulk in stool**. - While largely insoluble, **lignin** is considered the most characteristically insoluble fiber due to its highly cross-linked and rigid structure, which resists hydration even more effectively than cellulose.

Q: All of the following are examples of Dietary fibre except for which of the following?

Starch. ***Correct: Starch*** - **Starch** is a **polysaccharide** that serves as a **storage carbohydrate** in plants and is readily digestible by human enzymes, breaking down into glucose. - While it's a carbohydrate found in plant foods, it does not fit the definition of dietary fibre which is generally resistant to human digestive enzymes. *Incorrect: Pectin* - **Pectin** is a type of **soluble dietary fibre** found in fruits, particularly apples and citrus. - It forms a gel in water, contributing to satiety and helping to **lower cholesterol** and **regulate blood sugar**. *Incorrect: Lignin* - **Lignin** is a **non-carbohydrate dietary fibre** that provides structural support in plants. - It is an **insoluble fibre** and is resistant to breakdown by digestive enzymes, aiding in bulk formation in stool. *Incorrect: Cellulose* - **Cellulose** is a major component of **plant cell walls** and is a type of **insoluble dietary fibre**. - It adds bulk to stool, promoting regularity and preventing constipation.

Q: Which of the following is required for proper effects of Insulin?

Chromium. ***Chromium*** - **Chromium** is an essential trace mineral that plays a crucial role in enhancing the action of **insulin** by promoting its binding to cell receptors. - It is a key component of **glucose tolerance factor (GTF)**, which helps cells absorb glucose more efficiently. *Selenium* - **Selenium** is an antioxidant and is involved in thyroid hormone metabolism and immune function, but it does not directly facilitate insulin action. - While important for overall health, it has no known direct requirement for the proper effects of insulin. *Copper* - **Copper** is involved in various enzymatic reactions, iron metabolism, and connective tissue formation, but it is not directly required for insulin's proper function. - High levels of **copper** can even negatively impact glucose metabolism in some contexts. *Iron* - **Iron** is essential for oxygen transport in hemoglobin and myoglobin, as well as for many enzymatic processes, but it does not directly enhance insulin sensitivity or action [1]. - Both **iron deficiency** and **iron overload** can indirectly affect metabolic health but do not directly influence insulin's effects in the same way chromium does [2].

Q: What is the Net Protein Utilization (NPU) for eggs?

94. ***94*** - **Eggs** are considered a **high-quality protein source** with a Net Protein Utilization (NPU) of approximately **94**, indicating very efficient protein absorption and utilization by the body. - This high NPU reflects the excellent balance of **essential amino acids** in eggs, making them a benchmark for protein quality. *70* - An NPU of 70 is generally considered good but is lower than that of **eggs**, which are among the most efficiently utilized proteins. - This value might be typical for some **plant-based proteins** or mixtures of proteins with slightly less optimal essential amino acid profiles. *80* - An NPU of 80 indicates good protein quality but is still significantly lower than the **NPU of eggs**. - This value is often seen in high-quality **meat proteins** or well-balanced **dairy products**. *100* - An NPU of 100 would mean that all ingested protein is perfectly absorbed and utilized by the body without any loss, which is **theoretically impossible** for biological systems. - While some protein quality metrics might approach 100, **NPU is a measure of actual utilization** and never reaches 100 due to metabolic losses.

Q: What is the limiting amino acid in cereals?

Lysine. ***Lysine*** - **Lysine** is the **first limiting amino acid in cereals** (wheat, rice, corn), meaning it is present in the lowest proportion relative to the body's needs. - This deficiency can impact **protein synthesis** if cereals are the sole or primary protein source without supplementation. - Complementing cereals with **legumes** (rich in lysine but low in methionine) provides complete protein nutrition. *Methionine* - **Methionine** is typically the limiting amino acid in **legumes**, not cereals. - It works with cysteine to provide **sulfur-containing amino acids** essential for various metabolic processes. - This is why cereal-legume combinations (rice and lentils, corn and beans) are nutritionally complementary. *Tryptophan* - **Tryptophan** is an essential amino acid, but it is generally **not the primary limiting amino acid in cereals**. - While corn can be relatively low in tryptophan, **lysine deficiency is more significant** across cereal grains. - It is a precursor to **serotonin** and **niacin**. *Cysteine* - **Cysteine** is a non-essential amino acid, meaning the body can synthesize it from methionine. - While important for protein structure and function, it is **not considered a limiting amino acid** since it can be produced endogenously.

Q: Calcium absorption is hampered by

Phytates. ***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.

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

Lignin. ***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.

Q: Which is not a dietary fiber ?

Lactulose. ***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 1

What is the recommended daily protein intake for a healthy adult male?

Accepted Answer

1 gm/kg/day

Answer

0.5 gm/kg/day

Answer

1.5 gm/kg/day

Answer

2 gm/kg/day

Question 2

Which of the following statements about phosphorus is true?

Accepted Answer

Comprises about 1% of the total body weight

Answer

Parathormone acts on NaPiIIc receptors

Answer

Most of it (85%) is found in the bones

Answer

Dietary phosphorus deficiency is common in healthy individuals

Question 3

Which of the following dietary fibers is most characteristically insoluble in water?

Accepted Answer

Lignin

Answer

Pectin

Answer

Hemicellulose

Answer

Cellulose

Question 4

All of the following are examples of Dietary fibre except for which of the following?

Accepted Answer

Starch

Answer

Pectin

Answer

Lignin

Answer

Cellulose

Question 5

Which of the following is required for proper effects of Insulin?

Accepted Answer

Chromium

Answer

Selenium

Answer

Copper

Answer

Iron

Question 6

What is the Net Protein Utilization (NPU) for eggs?

Accepted Answer

94

Answer

70

Answer

80

Answer

100

Question 7

What is the limiting amino acid in cereals?

Accepted Answer

Lysine

Answer

Methionine

Answer

Tryptophan

Answer

Cysteine

Question 8

Calcium absorption is hampered by

Accepted Answer

Phytates

Answer

Protein

Answer

Lactose

Answer

Acid

Question 9

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

Accepted Answer

Lignin

Answer

Cellulose

Answer

Hemicellulose

Answer

Pectin

Question 10

Which is not a dietary fiber ?

Accepted Answer

Lactulose

Answer

Lignin

Answer

Pectin

Answer

Cellulose

Nutrition and Metabolism — MCQs

Nutrition and Metabolism — MCQs

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