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Questions and Answers
Which of the following vitamins are classified as fat-soluble?
Which of the following vitamins are classified as fat-soluble?
All vitamins are synthesized within the body.
All vitamins are synthesized within the body.
False
What is the deficit condition associated with the lack of vitamin C?
What is the deficit condition associated with the lack of vitamin C?
scurvy
The term vitamin was derived in ___ when an amine thought to prevent beriberi was isolated.
The term vitamin was derived in ___ when an amine thought to prevent beriberi was isolated.
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Match the following vitamins with their respective classes:
Match the following vitamins with their respective classes:
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Which of the following conditions may impair fat absorption, leading to a deficiency in fat-soluble vitamins?
Which of the following conditions may impair fat absorption, leading to a deficiency in fat-soluble vitamins?
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Excessive intakes of water-soluble vitamins may lead to toxicity.
Excessive intakes of water-soluble vitamins may lead to toxicity.
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Name a rich dietary source of vitamins.
Name a rich dietary source of vitamins.
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Vitamins may be used as special dietary supplements or as ___.
Vitamins may be used as special dietary supplements or as ___.
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Which of the following vitamins lack a nitrogen function?
Which of the following vitamins lack a nitrogen function?
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What is the major natural form of Vitamin A?
What is the major natural form of Vitamin A?
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Vitamin D2 is primarily obtained from animal sources.
Vitamin D2 is primarily obtained from animal sources.
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Name two functions of Vitamin A.
Name two functions of Vitamin A.
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Vitamin D is essential for the absorption and utilization of __________.
Vitamin D is essential for the absorption and utilization of __________.
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Match the following forms of Vitamin D with their sources:
Match the following forms of Vitamin D with their sources:
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Which condition can result from Vitamin A deficiency?
Which condition can result from Vitamin A deficiency?
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Vitamin D is often called the sunshine vitamin because of its relationship with sunlight.
Vitamin D is often called the sunshine vitamin because of its relationship with sunlight.
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What happens to beta-carotene in the intestines?
What happens to beta-carotene in the intestines?
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Vitamin D3 is synthesized in the skin when exposed to __________.
Vitamin D3 is synthesized in the skin when exposed to __________.
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Which food source is rich in Vitamin D3?
Which food source is rich in Vitamin D3?
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What is the primary role of vitamin D in the body?
What is the primary role of vitamin D in the body?
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Vitamin E is primarily involved in the formation of red blood cells.
Vitamin E is primarily involved in the formation of red blood cells.
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Name one source of vitamin K.
Name one source of vitamin K.
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Match the vitamin with its main role in the body:
Match the vitamin with its main role in the body:
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Ultraviolet B (UVB) radiation triggers the formation of vitamin D3 from the compound __________ in skin.
Ultraviolet B (UVB) radiation triggers the formation of vitamin D3 from the compound __________ in skin.
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What can result from a deficiency in vitamin D?
What can result from a deficiency in vitamin D?
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Vitamin E can be synthesized in the body in sufficient amounts.
Vitamin E can be synthesized in the body in sufficient amounts.
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What is a common dietary source of vitamin E?
What is a common dietary source of vitamin E?
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Vitamin E deficiency can result in __________ and muscle weakness.
Vitamin E deficiency can result in __________ and muscle weakness.
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Which of the following vitamins is known for its role in immune system function?
Which of the following vitamins is known for its role in immune system function?
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Study Notes
Vitamins
- Vitamins are organic substances, not synthesized within the body, essential in small amounts for the maintenance of normal metabolic functions.
- They do not furnish energy and are not utilized as building units for cellular structure.
- Lack of specific vitamins leads to deficiency states such as beriberi, rickets, scurvy, and xerophthalmia, or to conditions without definitive symptoms.
- The term vitamin was coined in 1911 when an amine was isolated from rice bran and believed to prevent beriberi.
- Vitamins vary chemically, ranging from a simple molecule like niacin to a complex one like cyanocobalamin.
- Vitamins are widely distributed in nature and ingested as constituents of various food substances, especially fresh fruits, leafy vegetables, whole grains, eggs, and liver.
- Vitamins obtained from natural sources and synthetics are indistinguishable nutritionally and therapeutically.
- Vitamins can be used as dietary supplements or as drugs.
- Vitamin supplements are considered foods for special dietary needs and are unnecessary in most cases with a balanced diet.
- Vitamins are considered drugs when taken to treat a condition of vitamin deficiency or to prevent imminent development of a disease.
- Vitamins are classified into two classes: fat-soluble vitamins (A, D, E, K) and water-soluble vitamins (C, B complex).
- Fat-soluble vitamins are stored in the body and their deficiencies are relatively rare. Excessive intakes may be toxic.
- Water-soluble vitamins are not stored to any significant extent in the body. Excess supplements are usually excreted in urine.
Fat-Soluble Vitamins
- Vitamins A, D, E, and K are fat-soluble.
- Their absorption from the intestinal tract is associated with that of lipids, and deficiency states may be caused by conditions that impair fat absorption.
- These conditions include pathologic situations such as biliary cirrhosis, cholecystitis, and sprue, and therapeutic situations such as cholestyramine regimens and excessive use of mineral oil laxatives.
Vitamin A (Retinol)
- Vitamin A is a term applied to all derivatives of β -ionone, other than the carotenoids.
- Retinol is the major natural form of the vitamin, but known forms include the acetate and palmitate esters of the alcohol.
- Retinol is readily absorbed from the normal intestinal tract and is stored in body tissues, especially the liver.
- Sources include fish liver oils, animal organs (heart, kidney, liver), and plant carotenoids in carrots and green leafy vegetables.
- Only carotenoids with at least one unhydroxylated β -ionone ring (α-, β -, and -y-carotene and cryptoxanthin) can be converted to vitamin A.
- Beta-carotene and related carotenoids (provitamin A substances) are cleaved by β -carotene oxygenase in mucosal cells of the intestine to yield retinal, most of which is promptly reduced in the presence of NADH to retinol.
- Uses include vision, growth and development, immune function, red blood cell formation, skin and bone formation, and regulating gene transcription.
- Deficiency can result in conditions including nyctalopia (night blindness), xerophthalmia, hyperkeratosis of the skin, growth retardation, and decreased resistance to infection.
Vitamin D
- Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol) are essential for the absorption and utilization of calcium.
- Vitamin D3 is found only in animal-sourced foods, whereas D2 primarily comes from plant sources and fortified foods.
- Vitamin D3 sources include oily fish and fish oil, liver, egg yolk, butter, and dietary supplements.
- Vitamin D2 sources include mushrooms grown in UV light, fortified foods, and dietary supplements.
- Vitamin D is known as the "sunshine vitamin" because ultraviolet light helps convert provitamin substances to vitamins D2 and D3.
- Vitamin D3 is produced in the skin through exposure to sunlight. Ultraviolet B (UVB) radiation from sunlight triggers the formation of vitamin D3 from the compound 7-dehydrocholesterol in skin.
- A similar process occurs in plants and mushrooms, where UVB light leads to the formation of vitamin D2 from ergosterol.
- Uses: assists in the absorption of calcium and phosphorus in the intestine, plays a role in bone and calcium homeostasis, maintains muscle and nerve contraction, important for immune system function, maintains general cellular function, and potential use in cardiovascular disease, cancer, diabetes, and multiple sclerosis.
- Deficiency states lead to rickets in children and osteomalacia in adults.
### Vitamin E (tocopherol)
- Vitamin E refers to various forms of α-tocopherol.
- Several structurally related tocopherol analogs also occur in nature, but these possess only low levels of vitamin E activity.
- Vitamin E sources include plant oils, green vegetables, whole grains, egg yolks, and meats.
- Wheat germ oil is a traditional natural source of vitamin E for therapeutic purposes.
- Vitamin E is the major lipid-soluble antioxidant.
- It protects cell membranes, proteins, and DNA from oxidation, contributing to cellular health.
- It prevents oxidation of polyunsaturated fatty acids and lipids in the cells.
- Other uses include formation of blood vessels and boosting of immune function.
- Deficiency can cause nerve and muscle damage resulting in loss of feeling in the arms and legs, loss of body movement control, muscle weakness, and vision problems. Another sign of deficiency is a weakened immune system.
### Vitamin K (naphthoquinone)
- Vitamin K1 (phytonadione, phylloquinone) is found in green leafy vegetables.
- Vitamin K2 (menaquinone) is found in dairy products and some fruits and vegetables.
- Vitamin K3 (Menadione) and Vitamin K4 (Menadiol) are synthetic forms.
- Vitamin K refers to 2- methyl-1,4-naphthoquinone and derivatives of this compound.
- Vitamin K is distributed widely in dairy products and many fruits and vegetables, with green leafy vegetables being especially good dietary sources.
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Description
This quiz explores the essential role of vitamins in maintaining normal metabolic functions and the consequences of their deficiency. It will cover various types of vitamins, their sources, and their importance in nutrition and health. Test your knowledge on the chemical nature and history of vitamins.
