1. Chapter 9 The Fat-Soluble Vitamins

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Fat-Soluble Vitamins
Vitamins A, D, E and K are fat-soluble vitamins.
Fat-soluble vitamins require bile and dietary fat for absorption.
Once absorbed, they are transported with fats through the lymphatic system in chylomicrons before entering the blood.
Fat-soluble vitamins can be stored in body fat, meaning that intakes can vary without a risk of deficiency (as long as there are average intakes over time).
Because they can be stored in body fat, fat-soluble vitamins are not easily excreted. This increases the risk of toxicity with high intakes.
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3. Absorption of Vitamins
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Fat soluble vitamins require _____ and _____ for absorption into the mucosal cell. a)
bile and lymph b)
lymph and dietary fat c)
lymph and chylomicrons d)
bile and dietary fat d
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Since vitamin A and carotenoids are bound to proteins in foods, ______ is necessary to release them for absorption.
Pepsin
Bile
Amylase
Lactase
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Vitamin A
Vitamin A is found preformed, from animal products or supplements, or in precursor form, from plant foods, in the diet.
Vitamin A plays a key role in
night vision
cell differentiation
growth regulation.
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Vitamin A
Preformed vitamin A compounds are known as retinoids.
In the diet, preformed Vit A is present as retinol bound to fatty acids. retinOl and retinAl are interconverted in the body.
Plants contain precursors to vitamin A known as carotenoids. Carotenoids can be converted into retinal in the intestinal mucosa and the liver. B carotene is not as well absorbed as preformed Vit A (about 12 mg dietary B carotene yeild 1 mg retinol).
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The carotenoid with the most vitamin A activity is _____. a)
Beta-carotene b)
Zeaxanthin c)
Lutein d)
Lycopene
A ….Carotenoids with no vitamin A activity include all the following: Lutein, Lycopene, Zeaxanthin
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Vitamin A in the Diet
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Beta-carotene is least plentiful in which food?
yellow squash
spinach
yellow apples
carrots c
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hypercarotenemia
Large intake of carotenoids. Not toxic as the conversion to retinoids is limited. Caused by excess carotenoids stored in adipose tissue.
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12. Vitamin A and the Visual Cycle
Retinoids include retinol, retinal, and retinoic acid.
Light strikes visual pigment, rhodopsin and changes from cis to trans form
Sends signal to the brain. Also frees some vit a.
Vit a can also impact the eye by promoting proper health of mucosal tissue. Without that, it becomes keratinized.
The visual pigment that helps transform energy from light into a nerve impulse sent to the brain is:
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Keratomalacia from vit A deficiency
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Vitamin A is stable except when exposed to: a)
heat b)
light c)
lack of oxygen d)
fat
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Which form of vitamin A is involved in vision?
carotenoids
preformed vitamin A
retinal
retinoic acid c
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16. Vitamin A and Gene Expression
Retinoic acid enters the cell and binds to protein receptor in the nucleus. It can turn on and off the production of proteins. Ie) glyconeogenesis in liver cells.
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Cell differentiation, or the process by which a cell becomes more specialized, is most affected by which form of vitamin A? a)
preformed vitamin A b)
retinal c)
retinoic acid d)
retinol c
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18. Vitamin A Deficiency and Toxicity
Vitamin A deficiency is a threat to the health, sight and lives of millions of children around the world.
Vitamin A deficiency can be caused by insufficient intake of vitamin A, fat, protein or zinc.
Preformed vitamin A can be toxic if taken in high amounts.
Medications made from vitamin A, such as Retin A or Accutane, can cause serious side effects.
Vit A and epithelial tissue. Zinc is necessary for proper vitamin A transport and metabolism.
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Vitamin D
Vitamin D is known as the “sunshine vitamin” because it can be produced in the skin by exposure to UV light.
Only a few foods are natural sources of Vitamin D, including liver, fatty fish, fish oils and egg yolks.
Vitamin D can be toxic at high levels, so there are strict limitations on the categories of foods that can be vitamin D-fortified.
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Vitamin D's primary function in the body is to a)
prevent anemia b)
regulate calcium and phosphorus levels c)
regulate iron levels in the body d)
support night vision
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Vitamin D
Vitamin D is important for
bone health
normal functioning of the parathyroid gland
regulation of the immune system.
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22. Vitamin D Deficiency and Toxicity
When vitamin D is deficient, dietary calcium cannot be absorbed efficiently and there can be improper bone mineralization and abnormalities in bone structure.
In children, vitamin D deficiency can result in rickets; in adults, osteomalacia.
Oversupplementation of vitamin D can result in high blood and urine calcium concentrations, depositing of calcium in blood vessels and kidneys, cardiovascular damage and possibly death.
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Vitamin D
Rickets is a syndrome characterized by bone deformities in children, and caused by vitamin D deficiency.
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Osteomalacia
A vitamin D deficiency disease in adults which is characterized by weak (principally affects bone remodeling
Low vitamin D levels have been found in 8% of women living in nursing homes, 6% of young women, and 1.6% of elderly people living in the community in Omaha, Nebraska
For people of south Asian (Indian subcontinent) descent living in the UK, 56% of elderly and 41% of the young have been found to have significantly lower levels of vitamin D than Caucasian controls.
May coexist with osteopersosis
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African Americans are at increased risk of vitamin D deficiency for all of the following reasons except:
Darkly pigmented skin filters out more light.
They spend less time in the sun than people of other ethnic origins.
Milk consumption is low.
Lactose intolerance is common. d
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Vitamin D in the Diet
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27. What macronutrient is the base for Vit D?
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28. Vitamin D from UV Light or the Diet
Cholecalciferol is a form of vitamin D, also called vitamin D3 or calciol. It is the unhydroxilated form of Vit D, formed right after 7-dehydrocholesterol is struck by light
Vit D’s main job is to keep blood calcium levels up (does in 3 ways: intestine, kidney, bone). When it is absent, not enough calcium is available to form the mineral deposits..
…. Cholecalciferol is a form of vitamin D, also called vitamin D3 or calciol. It is the unhydroxilated form of Vit D, formed right after 7-dehydrocholesterol is struck by light. Liver, kidneys dehydrocholesterol is turned to cholecholesterol.
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Vitamin E
Idenetified as the fat soluble component of grains important for fertility.
Vitamin E is also called tocopherol. (Greek tos: childbirth and phero: to bring forth)
Vitamin E has antioxidant properties.
Alpha-tocopherol is the form of vitamin E absorbed by the human body. The other forms cannot be distrubuted. The supplement form contains 8 different isomers, only ½ of which are active in the body.
Vitamin E absorption depends on normal fat absorption.
Once absorbed, vitamin E is incorporated into chylomicrons.
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30. Converting Vit E units (pg 403)
To estimate alpha tocopherol in foods
If values are given as mg alpha-Tes
Mg x0.8= mg alpha tocopherol
If values given in IUs
First determine if the source is synthetic or natural
IU natural alpha tocopherol x 0.67=mg alpha tocopherol
IU synthetic x0.47= mg alpha tocopherol
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Vit E
Roles of vitamin E?
Antioxidant
Preserves lipids such as LDL and PUFAs
maintains the integrity of cell membranes
Red Blood Cell: Vitamin E deficiency in newborns might result in hemolytic anemia.
Lung cells
Nervous system cells
protects against some environmental pollutants.
Heavy metals (lead, mercury), toxins (carbon tetrachloride, benzene), pollutants (ozone).
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In the liver, vitamin E is incorporated into _____ and from there distributed to other lipoproteins and delivered to cells.
Chylomicrons
VLDL
LDL
HDL b
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Vitamin E in the Diet
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Which is NOT considered a good source of vitamin E? a)
peanuts b)
soybean oil c)
fortified breakfast cereals d)
orange and yellow vegetables
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35. Vitamin E is an Antioxidant
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Vitamin K
Vitamin K was named for koagulation, the Danish word for coagulation.
Vitamin K is found in several forms, including phylloquinone and menaquinones.
Abnormal blood coagulation is the major symptom of vitamin K deficiency.
Vitamin K deficiency is very rare in the US.
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Vitamin K in the Diet
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38. A Summary of the Fat-Soluble Vitamins
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39. Copyright 2010, John Wiley & Sons, Inc.
Vitamin A toxicity occurs most frequently when large amounts of _________ is (are) ingested. a)
carrot juice b)
egg yolks c)
polar bear liver d)
vitamin A supplements
Above 3000 IU per day
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40. A Summary of the Fat-Soluble Vitamins
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The recommended intake of vitamin E is expressed in: a)
REs b) µg c)
alpha-tocopherol equivalents d)
mg alpha-tocopherol
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42. Benefits and Risks of Fat-Soluble Vitamin Supplements
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Trends in the modern diet have reduced the consumption of fruits and vegetables. This has reduced our intake of all of the following except vitamin ____. A D E K b
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A deficiency of vitamin A can result in a)
beriberi b)
goiter c)
scurvy d)
xerophthalmia
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Which of the fat soluble vitamins can be synthesized by bacteria in the intestine? a)
vitamin A b)
vitamin D c)
vitamin E d)
vitamin K d
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Long term use of antibiotics may result in vitamin K deficiency because: a)
antibiotics may interfere with absorption of the vitamin b)
antibiotics use vitamin K to function properly c)
antibiotics may change the bacterial flora in the gut, decreasing vitamin K production d)
antibiotics may promote other vitamins which compete with vitamin K for absorptionc
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Vitamin E's primary function in the body is: a)
to act as an antioxidant b)
to increase absorption of calcium in the small intestine c)
to regulate acid-base balance d)
to regulate phosphorus levels
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Chapter 9
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