Nutrition and Vitamins Quiz

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Questions and Answers

What is the primary function of calcitriol in the body?

Stimulating respiration rate

Maintaining adequate serum levels of calcium (correct)

Regulating blood pressure

Enhancing sodium reabsorption in the kidneys

Which factor primarily stimulates the formation of calcitriol in the kidneys?

Hormonal signals from the thyroid

Oxygen levels in the blood

Blood glucose levels

Serum calcium and phosphate ions (correct)

What condition is primarily associated with vitamin D deficiency in children?

Hyperparathyroidism

Nutritional rickets (correct)

Bone cancer

Osteoporosis

What is a consequence of vitamin D toxicity?

Hypercalcemia Signup and view all the answers

Which of the following nutrients is synthesized with the help of vitamin K?

Blood clotting proteins Signup and view all the answers

What is the recommended dietary allowance (RDA) of vitamin K for adult females?

90 μg/day Signup and view all the answers

Which form of vitamin K is derived from plant sources?

Phylloquinone Signup and view all the answers

How does calcitriol affect calcium reabsorption in the kidneys?

Decreases calcium loss in urine Signup and view all the answers

What is the primary function of retinol when released from the liver?

To transport through blood to extrahepatic tissues Signup and view all the answers

What is the severe effect of vitamin A deficiency?

Xerophthalmia Signup and view all the answers

Which vitamin is primarily responsible for the visual cycle in rod cells?

Retinol Signup and view all the answers

What condition may result from untreated vitamin A deficiency?

Corneal ulceration Signup and view all the answers

How does excessive intake of vitamin A manifest symptomatically?

Dry skin and liver enlargement Signup and view all the answers

What is the primary source of preformed vitamin A?

Animal sources Signup and view all the answers

What is the main source of vitamin D3?

Animal tissues Signup and view all the answers

Which form of vitamin D is considered biologically inactive until converted in vivo?

Cholecalciferol Signup and view all the answers

Which of the following accurately describes the function of vitamins?

Act as catalysts that release energy from macronutrients Signup and view all the answers

What major role does vitamin D play in the body?

Regulates calcium and phosphate metabolism Signup and view all the answers

How is one retinol activity equivalent (RAE) defined?

1 μg of retinol Signup and view all the answers

Which form of vitamin A cannot be converted back to retinol?

Retinoic acid Signup and view all the answers

What is the recommended dietary allowance (RDA) of retinol activity equivalents for adult males?

900 RAE Signup and view all the answers

What is the primary role of retinyl esters in the body?

Storage form of vitamin A Signup and view all the answers

Which process happens to retinyl esters in the intestinal mucosa?

They are hydrolyzed Signup and view all the answers

What distinguishes vitamins from macronutrients?

Vitamins are individual units, while macronutrients are linked Signup and view all the answers

What is the primary role of Vitamin K in blood clotting?

It activates the carboxylation of clotting factors. Signup and view all the answers

In which form does Vitamin K function during the carboxylation reaction of clotting factors?

Active/reduced form Signup and view all the answers

What effect does prolonged administration of menadione have in infants?

Prolonged jaundice and hemolytic anemia Signup and view all the answers

Which vitamin is necessary for the processing of carboxylated glutamic acid residues in clotting factors?

Vitamin K Signup and view all the answers

What is the primary impact of Vitamin E on cardiovascular disease (CVD)?

It acts as an antioxidant to reduce oxidative stress. Signup and view all the answers

What causes the deficiency of Vitamin K in newborns?

Sterility of the gut Signup and view all the answers

What is the role of anticoagulants like warfarin concerning Vitamin K?

They inhibit Vitamin K epoxide reductase. Signup and view all the answers

What factors influence the RDA for α-tocopherol?

Age, gender, and PUFA intake Signup and view all the answers

Study Notes

Fat-Soluble Vitamins

Fat-soluble vitamins are chemically unrelated organic compounds.
They cannot be synthesized in sufficient quantities by the human body.
They must be supplied through the diet.
They differ from macronutrients in several key ways: their structure (individual units not linked together), function (do not directly yield energy), and amount ingested (measured in micrograms or milligrams, not grams).

Classification of Vitamins

Vitamins are categorized into water-soluble and fat-soluble groups.
Fat-soluble vitamins include Vitamin A, Vitamin D, Vitamin E, and Vitamin K.
Water-soluble vitamins include vitamin C and various B vitamins.
Within the fat-soluble category, further subdivisions exist for each vitamin (e.g., retinol, retinal, retinoic acid for Vitamin A; ergocalciferol and cholecalciferol for Vitamin D etc.).

Vitamin A (Retinol)

Primarily obtained from animal sources (retinol).
Pre-formed vitamin A (retinol), a retinoid.
Daily Recommended Allowance (RDA) is 900 retinol activity equivalents (RAE) for males and 700 RAE for females.
1 RAE = 1 µg of retinol, or 12 µg of β-carotene, or 24 µg of other carotenoids.
Involved in visual cycle (rhodopsin).
Important for epithelial cell maintenance.
Involved in reproduction.
Deficiency -Mild: Nyctalopia (night blindness) -Severe: xerophthalmia (pathological dryness of conjunctiva and cornea)
Excess: hypervitaminosis A leading to dry skin, enlarged/cirrhotic liver, increased intracranial pressure, and potential teratogenicity in pregnant women.

Vitamin D (Calcitriol)

A group of sterols with a hormone-like function.
Active form: 1,25-dihydroxycholecalciferol (calcitriol).
Naturally found in fatty fish, liver, and egg yolk.
RDA for 1–70-year-olds is 15 µg/day, and 20 µg/day for those over 70 years.
Plays a key role in maintaining adequate serum calcium levels.
Affects calcium absorption in the intestines, bone calcium maintenance, and calcium reabsorption in the kidneys.
Deficiency leads to rickets in children and osteomalacia in adults.
Toxicity: high doses can cause loss of appetite, nausea, thirst, and weakness, along with hypercalcemia leading to calcium salt deposition in soft tissues (metastatic calcification).

Vitamin K

Sources include Vitamin K1 (phylloquinone) in plants and Vitamin K2 (menaquinones) in intestinal flora.
Used synthetically as menadione in supplements.
Essential for the synthesis of blood clotting proteins (factors II, VII, IX, and X).
Important function: blood clotting
Deficiency: extremely rare unless specific situations occur. One dose is given to newborns to prevent deficiency issues that can result in bleeding.

Vitamin E

Consists of eight tocopherols, with α-tocopherol being the most active.
Important antioxidant protecting against nonenzymatic oxidation.
Prevents oxidation of low-density lipoprotein (LDL) and peroxidation of polyunsaturated fatty acids (PUFAs).
RDA for adults is 15 mg/day.
Vegetable oils and liver are rich sources.
Deficiency effects: not as well studied compared to others.
Toxicity is relatively low with normal diets.

General Considerations

Ingesting excessive amounts of fat-soluble vitamins can lead to toxicity.
These vitamins, particularly Vitamin D and Vitamin A, are stored in the body and metabolized slowly.
The appropriate intake varies based on age, health conditions, and other factors.
Specific diseases or conditions may require adjusted intake amounts, and a doctor’s advice and assessment are necessary in all circumstances.

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Description

Test your knowledge on the functions and effects of essential vitamins in the body. This quiz covers topics like vitamin D, K, and A, including their roles, sources, and deficiency consequences. Perfect for students and health enthusiasts alike!