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Questions and Answers
Fat-soluble vitamins are excreted readily through urine.
Fat-soluble vitamins are excreted readily through urine.
False
Beta-carotene is a precursor to vitamin A and can be converted into retinol.
Beta-carotene is a precursor to vitamin A and can be converted into retinol.
True
Carotenoids can only be obtained from animal sources.
Carotenoids can only be obtained from animal sources.
False
Fat-soluble vitamins travel through the lymphatic system after absorption.
Fat-soluble vitamins travel through the lymphatic system after absorption.
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Vitamin K is classified as a water-soluble vitamin.
Vitamin K is classified as a water-soluble vitamin.
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Vitamin A deficiency can lead to night blindness due to a lack of vitamin A at the back of the eye.
Vitamin A deficiency can lead to night blindness due to a lack of vitamin A at the back of the eye.
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Keratinization of epithelial cells in the skin is a direct result of excessive vitamin A in the body.
Keratinization of epithelial cells in the skin is a direct result of excessive vitamin A in the body.
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A healthy adult can experience vitamin A deficiency symptoms within weeks of stopping the intake of vitamin A–containing foods.
A healthy adult can experience vitamin A deficiency symptoms within weeks of stopping the intake of vitamin A–containing foods.
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Vitamin A plays a significant role in the growth and development of children, including bone remodeling.
Vitamin A plays a significant role in the growth and development of children, including bone remodeling.
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Retinol-binding protein (RBP) is important for transporting vitamin A within the body.
Retinol-binding protein (RBP) is important for transporting vitamin A within the body.
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Vitamin A toxicity may result in night blindness.
Vitamin A toxicity may result in night blindness.
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Children are the most vulnerable to Vitamin A toxicity.
Children are the most vulnerable to Vitamin A toxicity.
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Vitamin D is considered an essential nutrient because it cannot be synthesized by the body.
Vitamin D is considered an essential nutrient because it cannot be synthesized by the body.
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Vitamin D requires activation in both the liver and kidneys.
Vitamin D requires activation in both the liver and kidneys.
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Keratinization is a result of Vitamin A deficiency.
Keratinization is a result of Vitamin A deficiency.
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Liver storage of Vitamin A usually prevents deficiency.
Liver storage of Vitamin A usually prevents deficiency.
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Beta-carotene can be genetically modified to increase Vitamin A content.
Beta-carotene can be genetically modified to increase Vitamin A content.
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Vitamin A is water-soluble.
Vitamin A is water-soluble.
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Bowed legs are a characteristic sign of rickets in children.
Bowed legs are a characteristic sign of rickets in children.
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Older people are at a lower risk of developing vitamin D deficiency due to their healthy skin.
Older people are at a lower risk of developing vitamin D deficiency due to their healthy skin.
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Vitamin D toxicity is unlikely to occur from excessive sun exposure.
Vitamin D toxicity is unlikely to occur from excessive sun exposure.
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Osteomalacia in adults is characterized by increased mineralization of bone.
Osteomalacia in adults is characterized by increased mineralization of bone.
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Vitamin D can be obtained from plant sources, making it less of a concern for vegetarians.
Vitamin D can be obtained from plant sources, making it less of a concern for vegetarians.
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The recommended dietary allowance (RDA) for vitamin D is lower for adults aged 19-30 years compared to younger individuals.
The recommended dietary allowance (RDA) for vitamin D is lower for adults aged 19-30 years compared to younger individuals.
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Oily fish and fortified milk are sources of vitamin D.
Oily fish and fortified milk are sources of vitamin D.
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The main consequence of vitamin D deficiency in children is an increased risk of fractures.
The main consequence of vitamin D deficiency in children is an increased risk of fractures.
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Vitamin K is primarily known for its role in bone health.
Vitamin K is primarily known for its role in bone health.
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A primary deficiency of vitamin K is common among adults.
A primary deficiency of vitamin K is common among adults.
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Vitamin E is stable and not destroyed by oxidation or heat.
Vitamin E is stable and not destroyed by oxidation or heat.
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Phylloquinone is a common form of Vitamin K found in animal foods.
Phylloquinone is a common form of Vitamin K found in animal foods.
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Vitamin K helps with the synthesis of proteins involved in blood clotting.
Vitamin K helps with the synthesis of proteins involved in blood clotting.
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Vitamin K plays a critical role in the blood-clotting process.
Vitamin K plays a critical role in the blood-clotting process.
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Newborn infants are at risk for hemorrhagic disease due to low plasma prothrombin concentrations.
Newborn infants are at risk for hemorrhagic disease due to low plasma prothrombin concentrations.
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Hemophilia is caused by a deficiency of Vitamin K.
Hemophilia is caused by a deficiency of Vitamin K.
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Vitamin K is synthesized primarily in the liver.
Vitamin K is synthesized primarily in the liver.
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Vitamin K can help reduce the risk of heart disease.
Vitamin K can help reduce the risk of heart disease.
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Vitamin K can help decrease bone turnover and prevent fractures.
Vitamin K can help decrease bone turnover and prevent fractures.
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Newborns are typically given a Vitamin K injection shortly after birth.
Newborns are typically given a Vitamin K injection shortly after birth.
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Antibiotics can interfere with the metabolism of vitamin K.
Antibiotics can interfere with the metabolism of vitamin K.
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Hemorrhagic disease can result from excessive vitamin K levels in the body.
Hemorrhagic disease can result from excessive vitamin K levels in the body.
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Vitamin K deficiency is very common.
Vitamin K deficiency is very common.
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The recommended daily allowance (RDA) of Vitamin K is 90 μg for adults.
The recommended daily allowance (RDA) of Vitamin K is 90 μg for adults.
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Study Notes
Fat Soluble Vitamins
- Fat-soluble vitamins differ from water-soluble vitamins in their digestion and absorption processes
- They require bile for digestion and absorption
- Fat-soluble vitamins travel through the lymphatic system
- Excesses are stored in the liver and adipose tissues
- They are not readily excreted, increasing the risk of toxicity
- Digestion and absorption follow a similar pathway to dietary fats
- Insoluble in water, packaged into chylomicrons
- Taken up by the liver, and can be stored
- Transported to other tissues via proteins
- Conditions that alter/hinder intestinal or fat absorption limit absorption
Vitamin A
- First fat-soluble vitamin recognized in 1913
- Precursor: beta-carotene
- Three active forms in the body: retinol, retinal, and retinoic acid
- Foods derived from plants provide carotenoids, some of which can be converted to vitamin A
- Carotenoids are pigments that give fruits and vegetables their yellow, orange, and red colors
- Beta-carotene, the most studied carotenoid, can be split to form retinol in the intestine and liver.
- 1 RAE = 1 µg retinol = 12 µg beta-carotene
- Two sources of vitamin A: pre-formed (retinyl ester) and pro-vitamin (beta-carotene)
- Vitamin A is converted to retinol
- Retinol is bound to RBP, then to retinal
- Retinal participates in vision
- Retinoic acid regulates growth
- Vitamin A sources: fortified milk, mango, spinach, carrots, apricots
- Function: vision, maintaining healthy epithelial tissue, reproduction, development, immunity, growth.
- Prevents damage to skin from the sun
- Maintains a clear cornea
- Converts light energy to nerve impulses in the retina
- Visual activity leads to repeated small losses of retinal, needing replenishment
Vitamin A Deficiency
- Large problem in developing countries
- Symptoms may not appear until after depletion of stores (1-2 years healthy adults, sooner for growing children)
- Liver stores 40-90% of total vitamin A
- Associated with adequacy of stores
- Retinol-binding protein (RBP) is important for vitamin transport
- Deficiency risks infectious diseases (like measles)
- Causes night blindness and blindness
- Bitot's spots: abnormal squamous cell proliferation and keratinization of the conjunctiva
- Possible cause of death
- Vitamin A deficiency causes keratinization in the epithelial cells in the skin, causing dry and scaly skin
- Reduced mucus production in the GI tract, decreasing digestion and absorption, and worsening malnutrition
Vitamin A Toxicity
- Develops when binding proteins are loaded
- Vitamin A is free to damage cells
- Concentrated amounts of preformed vitamin A (animal sources, fortified foods, supplements) are most vulnerable in children
- Can cause bone and birth defects
Vitamin D
- Not an essential nutrient (body synthesizes from cholesterol via sunlight)
- Requires two hydroxylation reactions in the liver and kidneys to become active
- Diseases affecting the liver or kidneys can interfere with Vitamin D activation
- Significant in bone making and maintenance
- Assists in calcium and phosphorous absorption, leading to denser and stronger bones
- Vitamin D influences parathyroid hormone levels, which affects vitamin D turnover rate
- Raises blood calcium concentrations in two ways: increase calcium synthesis and decrease calcium excretion
- Protects against cognitive decline in brain and nerve cells
- May protect against heart disease, inflammation, and brain disorders; type 2 diabetes
- There are misconceptions regarding a healthy diet's adequate Vitamin D amounts
- Latitude, season, time of day, cloud cover, skin melanin content, and sunscreen affect UV exposure, influencing Vitamin D synthesis.
- Adequate 5-30 minutes of unprotected sun exposure to face arms, hands, legs between 10 AM and 4 PM leads to sufficient synthesis
- Most people need some exposure to sunlight to maintain adequate Vitamin D levels
- Latitude, season, and time of day affect UV radiation exposure significantly
- Most of the world's population is at a risk for vitamin D deficiency
- Prolonged exposure to sun risks wrinkles and skin cancer, but reduced risks are possible with sunscreen
- Most People in the world meet at least some Vitamin D needs through sunlight exposure.
- Type B UV radiation with a wavelength between 290-320 nanometers penetrates the skin converting 7-dehydrocholesterol into previtamin D3. UVB radiation does not transmit through glass.
Vitamin D Deficiency
- Four contributing factors: lack of sunlight, dark skin, not consuming fortified milk, and lack of breastfeeding with supplementation
- Vitamin D deficiency leads to slower calbindin production.
- With insufficient calbindin, calcium cannot be absorbed adequately through GI tract
- Increases risks for several chronic diseases and osteoporosis- Vitamin D deficient adolescents don't reach their peak bone mass
- In rickets, the bones fail to calcify normally, leading to growth and skeletal abnormalities
- Bowed legs, and beaded ribs are symptoms
Vitamin D Deficiency: Specific Conditions
- Osteomalacia occurs in adults when there's poor bone mineralization
- Bones become increasingly soft, flexible, brittle, and deformed
- Osteoporosis occurs when there is failure to synthesize adequate Vitamin D or insufficient amounts received through foods.
- Leads to loss of calcium from bones and risk for fractures
Vitamin D Toxicity
- Most likely of the vitamins to have toxic effects- usually from supplements-
- Can raise blood calcium concentrations, form kidney stones, and harden blood vessels. Can cause death
Vitamin E
- Two categories: tocopherols (alpha, beta, gamma, delta) and tocotrienols
- Only alpha-tocopherol is maintained in the body
- Antioxidant that stops free radical reactions
- Protects cells and membranes and PUFA
- Dietary fats are necessary for absorption into the body
- Stored in adipose tissue, muscles, and cell membranes in the body
- a-tocopherol only one to have activity in human body
- Performs a key role as an antioxidant in the body
- Absorption requires dietary fats
- Stored in adipose tissue, muscles, and cell membrane of tissues
- Toxicity is rare; UL is 65 times greater than RDA for adults- Extremely high doses interfere with Vitamin K activity, causing hemorrhage
- RDA based on a-tocopherol form only
- Most of dietary vitamin E derives from vegetable oils and foods containing them
Vitamin E Deficiency
- Primary deficiency is rare
- Associated with diseases (specifically fat malabsorption, like cystic fibrosis)
- Prolonged deficiency leads to neuromuscular dysfunction, potentially affecting neurological symptoms
- Effects include split red blood cells as PUFA becomes oxidized, leading to erythrocyte hemolysis
Vitamin K
- Fat-soluble vitamin in two forms: phylloquinone (green leafy vegetables) and menaquinones (some animal foods and bacteria in the GI Tract)
- Plays a key role in blood coagulation (clotting)
- Essential for activation of clotting proteins (like prothrombin)
- Also helps with bone health- important for vitamin D dependent calcium regulation
- Important for blood clotting to help prevent and limit hemorrhaging
- A secondary vitamin K deficiency can occur due to fat absorption failure.
- Some drugs like antibiotics and anticoagulants may disrupt vitamin K synthesis
- Newborn infants often need a single dose of vitamin K at birth because their GI tract bacteria aren't established yet and placental and breast milk concentrations are low.
Vitamin K Toxicity
- Not common; no adverse effects with high intakes
- No set upper limit
- High doses may reduce the effectiveness of anticoagulant drugs
Vitamin and Mineral Supplements
- Healthy children and adults generally don't need Vitamin and Mineral supplements
- Meeting nutrient needs often through a variety of food sources is better
- Not consuming a diverse amount of fortified food may require supplement use.
- Who should not take supplements:
- Men and postmenopausal women (excess iron)
- Smokers (excess beta-carotene)
- Postmenopausal women (excess Vitamin A)
- Surgery patients (excess Vitamin E)
- Supplements are presumed safe until adverse reactions are documented.
- Supplements aren't obligated to meet any safety or effectiveness standards
- Products may not claim to "prevent, cure, diagnose, or mitigate" diseases.
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Description
This quiz covers essential information about fat-soluble vitamins, focusing on their sources, roles, and deficiency symptoms. Key topics include Vitamin A, its precursor beta-carotene, and the implications of vitamin deficiencies and toxicities. Test your knowledge on how these vitamins function in the body and their significance for growth and health.
