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Questions and Answers
What is the primary characteristic of fat soluble vitamins?
What is the primary characteristic of fat soluble vitamins?
Which vitamin is primarily absorbed through passive diffusion in the intestines?
Which vitamin is primarily absorbed through passive diffusion in the intestines?
What condition can result from a deficiency of vitamin K?
What condition can result from a deficiency of vitamin K?
What interferes with the absorption of vitamin K?
What interferes with the absorption of vitamin K?
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What is the primary function of vitamin K in the body?
What is the primary function of vitamin K in the body?
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What percentage of absorbed B12 in blood carriers Haptocorrin?
What percentage of absorbed B12 in blood carriers Haptocorrin?
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What is the estimated amount of B12 needed to prevent deficiency for about 3-5 years?
What is the estimated amount of B12 needed to prevent deficiency for about 3-5 years?
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Which of the following forms of cobalamin deficiency is more prevalent?
Which of the following forms of cobalamin deficiency is more prevalent?
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What occurs to the percentage of absorbed B12 in blood when ingesting 10 μg of the vitamin?
What occurs to the percentage of absorbed B12 in blood when ingesting 10 μg of the vitamin?
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What role does Ferritin serve in the body?
What role does Ferritin serve in the body?
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What is the effect of H2 receptor blockers on iron absorption?
What is the effect of H2 receptor blockers on iron absorption?
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What is the primary carrier of heme iron during digestion?
What is the primary carrier of heme iron during digestion?
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What is the half-life of Haptocorrin in the body?
What is the half-life of Haptocorrin in the body?
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What metal ion is uniquely associated with vitamin B12?
What metal ion is uniquely associated with vitamin B12?
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Which of the following is a consequence of a strict vegetarian diet?
Which of the following is a consequence of a strict vegetarian diet?
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Which organ primarily stores vitamin B12 in the body?
Which organ primarily stores vitamin B12 in the body?
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How much of the ingested dose of vitamin B12 is typically absorbed?
How much of the ingested dose of vitamin B12 is typically absorbed?
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What are the two forms of vitamin B12 used in the human body?
What are the two forms of vitamin B12 used in the human body?
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What percentage of total blood cobalamin resides as methylcobalamin?
What percentage of total blood cobalamin resides as methylcobalamin?
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Which protein in blood facilitates the transport of vitamin B12?
Which protein in blood facilitates the transport of vitamin B12?
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Which factor primarily contributes to vitamin B12 deficiency in the U.S.?
Which factor primarily contributes to vitamin B12 deficiency in the U.S.?
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Which form of folate is the most stable?
Which form of folate is the most stable?
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Where is folate primarily stored in the body?
Where is folate primarily stored in the body?
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What percentage of folate is typically lost during processing and preparation of food?
What percentage of folate is typically lost during processing and preparation of food?
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Which amino acid metabolism requires folate for the synthesis of methionine from homocysteine?
Which amino acid metabolism requires folate for the synthesis of methionine from homocysteine?
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What is the tolerable upper intake level of folate?
What is the tolerable upper intake level of folate?
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Which folate form is mainly found in supplements and fortified foods?
Which folate form is mainly found in supplements and fortified foods?
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Who benefits most from increased bioavailability of synthetic folic acid compared to naturally occurring folate?
Who benefits most from increased bioavailability of synthetic folic acid compared to naturally occurring folate?
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In which cells may folate involvement in cancer initiation occur?
In which cells may folate involvement in cancer initiation occur?
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What condition is characterized by incomplete synthesis of red blood cells due to abnormal DNA synthesis?
What condition is characterized by incomplete synthesis of red blood cells due to abnormal DNA synthesis?
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Which of the following is NOT a primary function of folate in the body?
Which of the following is NOT a primary function of folate in the body?
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What is the primary function of Hepcidin in iron metabolism?
What is the primary function of Hepcidin in iron metabolism?
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Which of the following is a poor dietary source of iron?
Which of the following is a poor dietary source of iron?
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What must happen to nonheme iron (Fe3+) before it can be absorbed in the intestines?
What must happen to nonheme iron (Fe3+) before it can be absorbed in the intestines?
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What is one of the adverse effects of high-dose oral iron supplements?
What is one of the adverse effects of high-dose oral iron supplements?
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What characterizes the structure of Hepcidin?
What characterizes the structure of Hepcidin?
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Which dietary factor can hinder iron absorption due to toxicity concerns?
Which dietary factor can hinder iron absorption due to toxicity concerns?
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What is facilitated by ferroportin in iron metabolism?
What is facilitated by ferroportin in iron metabolism?
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What can happen to free iron in the body if not managed properly?
What can happen to free iron in the body if not managed properly?
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Which condition is caused by inadequate vitamin D leading to decreased calcium absorption?
Which condition is caused by inadequate vitamin D leading to decreased calcium absorption?
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What is the main storage form of vitamin D in the body?
What is the main storage form of vitamin D in the body?
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Which of the following vitamins is primarily involved in preventing the oxidation of LDL cholesterol?
Which of the following vitamins is primarily involved in preventing the oxidation of LDL cholesterol?
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What is a common symptom associated with vitamin E deficiency?
What is a common symptom associated with vitamin E deficiency?
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During which developmental periods is folate particularly important?
During which developmental periods is folate particularly important?
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What effect does chronic ethanol use have on folate absorption?
What effect does chronic ethanol use have on folate absorption?
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What is the primary function of vitamin D in the context of calcium regulation?
What is the primary function of vitamin D in the context of calcium regulation?
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Which of these is a food source rich in tocopherols?
Which of these is a food source rich in tocopherols?
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What is the potential consequence of vitamin D deficiency on blood calcium levels?
What is the potential consequence of vitamin D deficiency on blood calcium levels?
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Which vitamin is associated with the prevention of pre-oxidation of unsaturated fatty acids?
Which vitamin is associated with the prevention of pre-oxidation of unsaturated fatty acids?
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What is a key role of calcium channel proteins in the body?
What is a key role of calcium channel proteins in the body?
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Which of the following conditions is NOT related to vitamin E deficiency?
Which of the following conditions is NOT related to vitamin E deficiency?
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What happens to cellular vitamin E levels when it becomes low?
What happens to cellular vitamin E levels when it becomes low?
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Which vitamin's requirement is based on the 2-R α-tocopherol forms?
Which vitamin's requirement is based on the 2-R α-tocopherol forms?
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Study Notes
Fat Soluble Vitamins (K, A, D, E)
- Closely linked to lipid transport and absorption
- Incorporated into micelles
- Transported to tissues via lipoproteins
- Absorption can be affected by very low-fat diets
- Primarily stored with body lipids, though storage varies
Vitamin/Mineral Sources, Digestion, Absorption, Function, and Deficiency
-
Vitamin K:
- Plant sources (phylloquinone, K1) & animal sources (menaquinone, K2)
- No digestion needed for K in oils.
- Absorbed via passive diffusion and scavenger receptor class B
- Crucial for post-translational carboxylation of proteins and involved in blood clotting.
- Deficiency is rare in healthy adults. Low serum VK, bleeding.
-
Vitamin A:
- Found in liver and dairy products in retinoid form.
- Carotenoids in plant foods.
- Hydrolysis of esters in the small intestine by ester hydrolases is necessary.
- Absorbed through intestinal mucosal cells as retinyl esters, carotenoids into chylomicrons via intestinal mucosal cells.
- Crucial for vision, gene expression, and cell differentiation, growth and reproduction. Important in bone metabolism.
- Deficiency may result in vision problems, impaired reproduction, and growth problems.
-
Vitamin D:
- Sources include animal foods (cholecalciferol, D3) and plant ergosterol.
- No digestion needed.
- Absorbed via scavenger receptor class B type 1, into chylomicrons and lymph or portal blood
- Essential for calcium and phosphorus homeostasis, cell differentiation, antiproliferative and immunomodulatory functions.
- Deficiency leads to rickets in children and osteomalacia in adults.
-
Vitamin E:
- Sources include plants (tocopherols, tocotrienols) and animal products (a-tocopherol).
- Not needed for digestion, found in plasma as other vitamers not incorporated into lipoproteins, incorporated into chylomicrons.
- Essential in cellular level to maintain integrity of membranes and lipoproteins.
- Deficiency is rare.
-
Folate:
- Sources include leafy greens and fortified foods.
- Digestion is not needed for folic acid, reduced form of folate is in liver to dihydrofolate (DHF) and then to tetrahydrofolate (THF).
- Absorbed by hydrolysis and use of certain enzymes. -Essential for DNA synthesis, amino acid metabolism, and homocysteine metabolism
- Deficiency leads to megaloblastic and macrocytic anemia.
-
Vitamin B12 (Cobalamin):
- Sources include animal products.
- Digestion is needed for B12, involved in uptake by scavenger receptor class B type 1
- Essential for nerve health and red blood cell formation, DNA synthesis.
- Deficiency is rare in healthy adults, often caused by inadequate absorption.
-
Iron:
- Sources are heme from animal products and non-heme from plant foods.
- Digestion is needed since heme must be hydrolyzed by proteases. Non-heme must be reduced and hydrolyzed.
- Absorbed in small intestine by various mechanisms.
- Essential for oxygen transport (hemoglobin, myoglobin), cellular function, important in energy metabolism.
- Deficiency leads to anemia.
-
Zinc:
- Sources include animal products and plant sources.
- Digestion needed.
- Absorbed by various mechanisms, decreased by antacids.
- Essential in multiple biological roles, including catalytic-structural integrity of enzymes, as well as regulatory roles such as gene expression and cell growth.
- Deficiency can lead to various health issues.
-
Copper:
- Sources include shellfish and organ meats
- Transported in blood on albumin and a-2 macroglobulin.
- Absorbed by various mechanisms, reduced by alkaline environment and phytate.
- Essential for various enzyme activities and synthesis of important proteins like ceruloplasmin. Crucial for iron metabolism.
- Deficiency can lead to anemia, connective tissue issues, and neurological symptoms.
- Excess can be toxic.
-
Magnesium:
- Sources include nuts, seeds, legumes, and whole grains.
- Digestion not needed, but transport and absorption dependent on several mechanisms.
- Absorbed in small intestine by various mechanisms and primarily controlled by kidneys,
- Essential for nerve impulses, muscle function, bone health, and energy production.
- Deficiency can lead to heart issues and neuro issues.
-
Phosphorus:
- Sources - animal products, plants, processed foods.
- Digestion not needed.
- Absorbed in small intestine by passive diffusion and NPT2b (mostly in ileum).
- Essential for energy transfer, bone health and proper function of cells and cellular activities.
- Deficiency is rare.
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Description
Explore the essential fat soluble vitamins K, A, D, and E, their sources, absorption mechanisms, functions, and potential deficiencies. Understand how dietary fats influence the transport and storage of these vitamins in the body.
