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Questions and Answers
What is the primary natural form of vitamin A relevant to human health?
What is the primary natural form of vitamin A relevant to human health?
Which vitamin is synthesized in the skin upon exposure to ultraviolet B (UVB) radiation?
Which vitamin is synthesized in the skin upon exposure to ultraviolet B (UVB) radiation?
What condition is associated with a deficiency of vitamin D in children?
What condition is associated with a deficiency of vitamin D in children?
Which vitamin is primarily responsible for protecting cell membranes from oxidation?
Which vitamin is primarily responsible for protecting cell membranes from oxidation?
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What is the role of vitamin K in the human body?
What is the role of vitamin K in the human body?
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Which food source is primarily associated with vitamin D2?
Which food source is primarily associated with vitamin D2?
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Which vitamin deficiency is most commonly associated with impaired blood clotting?
Which vitamin deficiency is most commonly associated with impaired blood clotting?
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Which vitamin plays a significant role in gene transcription regulation?
Which vitamin plays a significant role in gene transcription regulation?
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Which of the following is a condition that can result from a vitamin A deficiency?
Which of the following is a condition that can result from a vitamin A deficiency?
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What is the main dietary source of vitamin E?
What is the main dietary source of vitamin E?
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Which of the following vitamins is considered water soluble?
Which of the following vitamins is considered water soluble?
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What is the primary function of vitamins in the body?
What is the primary function of vitamins in the body?
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Which vitamin is most likely to become toxic if consumed in excessive amounts?
Which vitamin is most likely to become toxic if consumed in excessive amounts?
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Which condition is most likely associated with a deficiency of fat soluble vitamins?
Which condition is most likely associated with a deficiency of fat soluble vitamins?
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What distinguishes the storage capability of water soluble vitamins from fat soluble vitamins?
What distinguishes the storage capability of water soluble vitamins from fat soluble vitamins?
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What is the origin of the term 'vitamin'?
What is the origin of the term 'vitamin'?
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Which of the following vitamin sources is most effective in preventing deficiency diseases?
Which of the following vitamin sources is most effective in preventing deficiency diseases?
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How are vitamins absorbed from the intestinal tract?
How are vitamins absorbed from the intestinal tract?
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In what form are synthetic vitamins recognized in terms of their nutritional quality?
In what form are synthetic vitamins recognized in terms of their nutritional quality?
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What is a major consequence of vitamin E deficiency?
What is a major consequence of vitamin E deficiency?
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Which form of vitamin D is primarily obtained from animal sources?
Which form of vitamin D is primarily obtained from animal sources?
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Which of the following carotenoids can be converted into vitamin A?
Which of the following carotenoids can be converted into vitamin A?
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What is one of the primary roles of vitamin D in relation to calcium?
What is one of the primary roles of vitamin D in relation to calcium?
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Which vitamin's deficiency can lead to xerophthalmia?
Which vitamin's deficiency can lead to xerophthalmia?
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What is a significant dietary source of vitamin K?
What is a significant dietary source of vitamin K?
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Which vitamin is primarily involved in gene transcription regulation?
Which vitamin is primarily involved in gene transcription regulation?
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The primary commercial sources of vitamin A were historically derived from which of the following?
The primary commercial sources of vitamin A were historically derived from which of the following?
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What is the primary function of vitamin K in the human body?
What is the primary function of vitamin K in the human body?
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Which vitamin can result in rickets if deficient during childhood?
Which vitamin can result in rickets if deficient during childhood?
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Which of the following options correctly describes the classification of vitamins?
Which of the following options correctly describes the classification of vitamins?
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What is a common consequence of excessive intake of fat soluble vitamins?
What is a common consequence of excessive intake of fat soluble vitamins?
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Which situation could lead to a deficiency in fat soluble vitamins?
Which situation could lead to a deficiency in fat soluble vitamins?
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Which vitamin is classified as water soluble?
Which vitamin is classified as water soluble?
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What distinguishes vitamins from other nutrients, according to the content provided?
What distinguishes vitamins from other nutrients, according to the content provided?
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What was the origin of the term 'vitamin'?
What was the origin of the term 'vitamin'?
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What is a characteristic of vitamins obtained from synthetic sources compared to natural sources?
What is a characteristic of vitamins obtained from synthetic sources compared to natural sources?
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Which of the following represents a distinctive deficiency state caused by vitamin deficiency?
Which of the following represents a distinctive deficiency state caused by vitamin deficiency?
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What happens to excess intake of water soluble vitamins in the body?
What happens to excess intake of water soluble vitamins in the body?
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Which of the following best describes the role of vitamins obtained from food substances?
Which of the following best describes the role of vitamins obtained from food substances?
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Study Notes
Vitamins: Introduction
- Vitamins are organic compounds, not synthesized in the human body, that are essential in small amounts for normal metabolic functions.
- They do not provide energy nor are they used as building blocks for cellular structures.
- Vitamin deficiency can result in specific deficiency conditions like beriberi, rickets, scurvy, and xerophthalmia, or in conditions without distinctive symptoms.
- The term "vitamin" was coined in 1911 when an amine that prevented beriberi was isolated from rice bran; this essential or vital amine was called a vitamin.
- Vitamins are chemically diverse, ranging from simple molecules like niacin to complex molecules like cyanocobalamin.
- Vitamins are widely distributed and typically ingested through various foods.
- Fresh fruits, leafy vegetables, whole grains, eggs, and liver are rich sources of vitamins.
- Vitamins obtained from natural sources and synthetically prepared versions are indistinguishable biochemically, nutritionally, and therapeutically.
Classification and Storage of Vitamins
- Vitamins are classified into two categories: fat-soluble vitamins (A, D, E, K) and water-soluble vitamins (C, B complex).
- Fat-soluble vitamins are stored in the body, making deficiencies relatively rare. However, excessive intake can be toxic.
- Water-soluble vitamins are not stored in the body to a significant extent. Excess supplements of these vitamins are typically excreted in urine.
Fat-Soluble Vitamins
- Vitamins A, D, E, and K are fat-soluble and their absorption from the intestinal tract is linked to lipid absorption.
- Conditions that impair fat absorption can lead to vitamin deficiencies. These include:
- Pathological conditions like biliary cirrhosis, cholecystitis, and sprue
- Therapeutic situations such as cholestyramine regimens and excessive use of mineral oil laxatives
Vitamin A (Retinol)
- Vitamin A encompasses all derivatives of β-ionone, excluding carotenoids.
- Retinol is the primary natural form of Vitamin A, with other known forms including acetate and palmitate esters of the alcohol.
- Retinol is readily absorbed (80 to 90%) from the normal intestinal tract and is stored in body tissues, particularly the liver.
- Approximately one-third of ingested Vitamin A is stored under normal circumstances.
Sources of Vitamin A
- Fish liver oils are natural sources of Vitamin A and were formerly its primary commercial sources.
- Animal organs (heart, kidney, liver) also contain significant amounts of Vitamin A.
- Certain plant carotenoids found in carrots and green leafy vegetables contribute to Vitamin A activity.
- 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 of Vitamin A
- Vision: essential for vision, particularly night vision.
- Growth and Development: crucial for normal growth and development.
- Immune function: supports immune system function.
- Red Blood Cell Formation: plays a role in red blood cell production.
- Skin and Bone Formation: contributes to healthy skin and bone formation.
- Regulating Gene Transcription: involved in regulating gene transcription.
Vitamin A Deficiency
- Vitamin A deficiency can cause:
- Nyctalopia (night blindness)
- Xerophthalmia (dryness of the conjunctiva and cornea of the eye)
- Hyperkeratosis of the skin (thickening of the skin)
- Growth retardation (slow or stunted growth)
- Decreased resistance to infection (weakened immune system)
Vitamin D
- Vitamin D encompasses several related steroids and their metabolites, essential for the absorption and utilization of calcium.
- The two forms of Vitamin D, D2 (ergocalciferol) and D3 (cholecalciferol), differ depending on their food sources.
- Vitamin D3: Found in animal-sourced foods.
- Vitamin D2: Found in plant sources and fortified foods.
Sources of Vitamin D3
- Oily fish and fish oil
- Liver
- Egg yolk
- Butter
- Dietary supplements
Sources of Vitamin D2
- Mushrooms (grown in UV light)
- Fortified foods
- Dietary supplements
Vitamin D & Sunlight
- Vitamin D is sometimes called the "sunshine vitamin" because ultraviolet light is involved in the conversion of provitamin substances to vitamins D2 and D3.
- 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, a compound found in plant oils.
- Spending time outdoors, lightly clad and without sunscreen, may help you obtain adequate Vitamin D.
Uses of Vitamin D
- Calcium and Phosphorus Absorption: assists in the absorption of calcium and phosphorus in the intestine. -Bone and Calcium Homeostasis: plays a crucial role in bone and calcium homeostasis. -Muscle and Nerve Contraction: maintains muscle and nerve contraction.
- Immune System Function: important for immune system function.
- General Cellular Function: maintains general cellular function in all cells of the body
- Other uses: May be beneficial in cardiovascular disease, cancer, diabetes, and multiple sclerosis.
Vitamin D Deficiency
- Deficiency states lead to:
- Rickets (a condition characterized by soft and weak bones) in children.
- Osteomalacia (softening of the bones) in adults.
Vitamin E (tocopherol)
- Vitamin E refers to various forms of α-tocopherol.
- Several structurally related tocopherol analogs are also found in nature, including β-, γ-, and δ-tocopherols, but these possess low levels of Vitamin E activity.
Sources of Vitamin E
- Plant oils, green vegetables, whole grains, egg yolks, and meats are common sources of Vitamin E.
- Wheat germ oil is a traditional natural source of Vitamin E for therapeutic purposes.
Uses of Vitamin E
- Antioxidant: Vitamin E is the primary lipid-soluble antioxidant, protecting cell membranes, proteins, and DNA from oxidation.
- Cellular Health: it contributes to overall cellular health.
- Polyunsaturated Fatty Acid Oxidation Prevention: prevents oxidation of the polyunsaturated fatty acids and lipids in the cells.
- Blood Vessel Formation: contributes to blood vessel formation.
- Immune Function Boosting: enhances immune function.
Vitamin E Deficiency
- 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.
- Weakened immune system.
Vitamin K (naphthoquinone)
- Vitamin K encompasses 2-methyl-1,4-naphthoquinone and derivatives of this compound.
Forms of Vitamin K
- Vitamin K1 (phytonadione, phylloquinone): Found in plants.
- Vitamin K2 (menaquinone): Produced by bacteria in the gut.
- Vitamin K3 (Menadione): Synthetic form of Vitamin K.
- Vitamin K4 (Menadiol): Synthetic form of Vitamin K.
Sources of Vitamin K
- Widely distributed in dairy products, fruits, and vegetables, with green leafy vegetables being particularly good sources.
- The intestinal microflora provides a significant portion of the normal human supply of Vitamin K.
Uses of Vitamin K
- Blood Clotting: Primarily involved in blood clotting (antihemorrhagic activity).
- Warfarin Overdose Treatment: Used to treat bleeding events resulting from warfarin overdose.
- Bone Protein Metabolism: Aids in the metabolism of bone proteins (osteocalcin).
- Bone Mineralization: Without Vitamin K, osteocalcin cannot bind to the minerals that form bones, leading to poor bone mineralization.
- Blood Calcium Levels Regulation: involved in regulating blood calcium levels.
Vitamin K Deficiency
- Hemorrhage is the most common symptom of Vitamin K deficiency.
Vitamins
- Vitamins are organic substances essential for normal metabolic functions, but they do not provide energy or become building blocks for cellular structure.
- Vitamin deficiency can lead to specific conditions like beriberi, rickets, scurvy, xerophthalmia, or other symptoms.
- Vitamins are chemically diverse, ranging from simple structures like niacin to complex ones like cyanocobalamin.
- Fresh fruits, leafy vegetables, whole grains, eggs, and liver are abundant sources of vitamins.
- Vitamins obtained from natural sources and synthetically are indistinguishable biochemically, nutritionally, and therapeutically.
- Vitamins can be classified into two classes: fat-soluble (A, D, E, K) and water-soluble (C, B complex).
- Fat-soluble vitamins are stored in the body, but excessive intake can be toxic.
- Water-soluble vitamins are not stored significantly and excess is usually excreted through urine.
Fat-Soluble Vitamins
- Absorption of fat-soluble vitamins (A, D, E, K) from the intestinal tract is linked to lipid absorption.
- Conditions impairing fat absorption, like biliary cirrhosis, cholecystitis, sprue, or therapeutic regimens involving cholestyramine and mineral oil laxatives, can lead to deficiencies.
Vitamin A (Retinol)
- Vitamin A refers to derivatives of β-ionone, excluding carotenoids.
- Retinol is the primary natural form, while acetate and palmitate esters are also known.
- The body readily absorbs (80-90%) retinol from the intestinal tract and stores it in tissues, especially the liver.
- Fish liver oils are natural sources of vitamin A and were once its primary commercial source.
- Animal organs (heart, kidney, liver) and certain plant carotenoids in carrots and green leafy vegetables contribute to vitamin A intake.
- Only carotenoids with an unhydroxylated β-ionone ring (α-, β-, and γ-carotene and cryptoxanthin) can be converted to vitamin A.
- β-carotene and related carotenoids are cleaved by β-carotene oxygenase in intestinal mucosal cells to yield retinal, which is reduced to retinol in the presence of NADH.
- Vitamin A deficiency causes various conditions including night blindness (nyctalopia), xerophthalmia, skin hyperkeratosis, growth retardation, and decreased resistance to infection.
Vitamin D
- Vitamin D2 (ergocalciferol) and D3 (cholecalciferol) are essential for calcium absorption and utilization.
- Vitamin D3 is found solely in animal-sourced foods while D2 originates from plant sources and fortified foods.
- Oily fish, fish oil, liver, egg yolk, butter, and dietary supplements are sources of D3.
- Mushrooms (grown in UV light), fortified foods, and supplements supply D2.
- Ultraviolet light (UVB) triggers the conversion of 7-dehydrocholesterol in skin to vitamin D3.
- A similar process occurs in plants and mushrooms where UVB light converts ergosterol to vitamin D2.
- Regular outdoor time, lightly clad and without sunscreen, may fulfill vitamin D requirements.
- Vitamin D aids in intestinal calcium and phosphorus absorption, plays a role in bone and calcium homeostasis, maintains muscle and nerve contraction, supports immune function, and contributes to general cellular function.
- Deficiency leads to rickets in children and osteomalacia in adults.
Vitamin E (Tocopherol)
- Vitamin E encompasses various forms of α-tocopherol, including β-, γ-, and δ-tocopherols, which possess less vitamin E activity.
- The body typically obtains sufficient vitamin E from dietary sources.
- Plant oils, green vegetables, whole grains, egg yolks, and meats are dietary sources of vitamin E.
- Wheat germ oil is a traditional natural source for therapeutic purposes.
- Vitamin E is a major lipid-soluble antioxidant, protecting cell membranes, proteins, and DNA from oxidation, contributing to cellular health.
- It prevents oxidation of polyunsaturated fatty acids and lipids in cells.
- Vitamin E deficiency can cause nerve and muscle damage, leading to loss of feeling in limbs, impaired movement control, muscle weakness, and vision issues.
- A weakened immune system is another deficiency sign.
Vitamin K (Naphthoquinone)
- Vitamin K includes 2-methyl-1,4-naphthoquinone and its derivatives.
- Dairy products, fruits, vegetables, especially green leafy ones are sources of vitamin K.
- The intestinal microflora contributes significantly to the human supply of vitamin K.
- Vitamin K primarily functions in blood clotting (antihemorrhagic activity) and is used for bleeding events caused by warfarin overdose.
- It aids in bone protein metabolism (osteocalcin).
- Without vitamin K, osteocalcin cannot bind to bone-forming minerals, resulting in poor bone mineralization.
- Vitamin K regulates blood calcium levels.
- Hemorrhage is the most common symptom of vitamin K deficiency.
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Description
This quiz provides an overview of vitamins, their importance in human nutrition, and their role in metabolic functions. It covers types of vitamins, deficiency conditions, and sources of vitamins in a diet. Test your knowledge of these essential nutrients and their biochemical significance.
