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UF / Science / HUN 2201 / How can you describe the process of vitamin d synthesis and name the f

How can you describe the process of vitamin d synthesis and name the f

How can you describe the process of vitamin d synthesis and name the f

Description

School: University of Florida
Department: Science
Course: Fundamentals of Human Nutrition
Professor: Laura acosta
Term: Spring 2017
Tags:
Cost: 50
Name: Quizzam 2 Study Guide
Description: Study Guide & notes
Uploaded: 03/23/2017
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HUN2201 Exam 2 Study Guide:  


How can you describe the process of vitamin d synthesis and name the fully activated form of vitamin d in the body?



Quizzam Part 2: Vitamins  

General:  

Describe general differences (keeping in mind there are always exceptions) between fat-soluble and water-soluble  vitamins, in terms of:  

• How they’re absorbed  

o Fat Soluble  

▪ Carried with dietary fats via chylomicrons  

▪ Require fat for absorption  

o Water Soluble  

▪ Absorbed from the small intestine  

• Ability of the body to store them

o Fat Soluble  

▪ Stored in the liver, adipose tissue  


What are the factors that can inhibit synthesis of vitamin d in the skin?



o Water Soluble  

▪ Excess is excreted, stored in cytoplasm of cells  

• Potential for toxicity  

o Fat Soluble  

▪ More potential for toxicity  

o Water Soluble  

▪ Less potential for toxicity but there are exceptions  We also discuss several other topics like What does the energy consumption of the us look like? what do we use for energy production?

• Stability to heat/cooking  

o Fat Soluble  

▪ Less vulnerable to handling and cooking losses, more stable  

o Water Soluble  

▪ More vulnerable to handling and cooking losses, less stable

Topic 1: Fat-Soluble Vitamins (A, D, E, and K)  


What are the the process of vitamin e reactivation, and identify the water-soluble vitamin that is involved /



• Know which one(s) have the most potential to be toxic  

- Vitamin D

• Distinguish between pre-formed vitamin A versus pro-vitamin A carotenoids, and know what foods are good  sources of each  

A. Retinoids

o Pre- formed vitamin A

o Retinol (alcohol form), Retinal (aldehyde form), Retinoic acid (acid form) Don't forget about the age old question of A place is defined by its what?
Don't forget about the age old question of What is the meaning of clavicle?

Food sources  

• Liver, fish oils, eggs  

• Milk and fortified cereals  

B. Pro- Vitamin A Carotenoids (precursors)  

o Β (beta) -carotene

o 1/12 of the Vitamin A activity of retinol

o 12 mcg β-carotene = 1 mcg retinol

o Α (alpha) -carotene

o 1/24 of the Vitamin A activity of retinol

o 24 mcg α-carotene = 1 mcg retinol

o β-cryptoxanthin If you want to learn more check out In primate adaptive trends phylum means what?

o 1/24 of the Vitamin A activity of retinol

o 24 mcg β-cryptoxanthin= 1 mcg retinol

Food sources

o Vegetables  

∙ Dark green, orange/deep yellow  

o Some fruits  

• Discuss the role of vitamin A in supporting healthy vision, and name the protein that retinal is a component  of, that converts light impulses to nerve impulses  

o Vision (retinal)

o Maintenance of the cornea

o Component of rhodopsin  

▪ Protein in rod cells  

▪ Converts light impulses to nerve impulses  

o Important for night vision and adjustment to changes in lighting  

• Describe the process of vitamin D synthesis and activation, and  

name the fully activated form of vitamin D in the body  

- Synthesis  

o Occurs in skin  If you want to learn more check out What is the meaning of civil forfeiture?

o Stimulus= UV light  

o Precursor is made from cholesterol  

- Activation  

o Must be activated before they can fully function  

o Hydroxylation steps in liver and kidney  

▪ Adding of an –OH group  

• List/describe factors that can inhibit synthesis of vitamin D in the  

skin  

o Darker skin  

o Lack of sunscreen

▪ Wearing sunscreen  Don't forget about the age old question of What is the meaning of product complexity?

▪ Latitude  

• Distinguish among the different forms of vitamin E in terms of their abundance in the body and their  biological activity  

• Describe the process of vitamin E reactivation, and identify the water-soluble vitamin that is involved  1. Antioxidants, such as vitamin E neutralize free radicals by donating on of their own electrons  2. The destructive chain reaction is stopped, but vitamin E is no longer active  

3. Like vitamin E, vitamin C acts as an antioxidant; it also restores vitamin E to its active form

• Describe why pre-term infants are at increased risk of erythrocyte hemolysis and anemia, and how vitamin E  can help  

o Premature Infants transition to life outside the womb cause a drastic decrease in EPO synthesis  causing a decrease in RBC production and a shorter lifespan  

o RBCs in the pre-term infant are fragile, and highly susceptible to free radical damage

o High rate of oxidation of polyunsaturated fatty acids in cell membrane causing hemolysis  o Significant blood is also lost due to frequent blood tests  

• Explain why infants receive a vitamin K injection at birth  

o All babies are born with low levels of vitamin K  

Topic 2: Water-Soluble Vitamins (Thiamin, Riboflavin, Niacin, Pantothenic Acid, Biotin, Vitamin B6,  Folate, Vitamin B12, Choline, and Vitamin C)  

• Know which one(s) have the most potential to be toxic  

- Vitamin B6

• Describe what is meant by macrocytic or megaloblastic anemia, and what nutrient deficiencies it can result  from  

o Large, immature red blood cells  

o Nucleated  

o Low oxygen carrying capacity  

- Results from Folate & B12 deficiencies  

• Describe the characteristic hallmarks of beriberi and pellegra  

- Beriberi- B1 (thiamin) Deficiency  

o Dry-damage to nervous systems characterized by muscle weakness in arms & legs o Wet-damage to cardiovascular system characterized by dilated blood vessels, edema - Pellagra- B3 (Niacin) Deficiency

o causing diarrhea, dermatitis, dementia, and eventually death (4 D’s)

• Comment on the stability of riboflavin to heat and light  

- Destroyed by UV light but stable during cooking  

• Identify water-soluble vitamins that are readily destroyed by heat and/or light  

- Pantothenic Acid B5

- Biotin  

- Vitamin C

• Describe how niacin can be synthesized in the body  

- Can be biosynthesized from the amino acid tryptophan.

• Explain the potential danger in taking high-dose folic acid supplements for someone with a vitamin B12 deficiency  

- It will cure the anemia and thereby mask the B12 deficiency and nerve damage will continue  • Identify populations most at risk of deficiency for various water-soluble vitamins, especially thiamin, vitamin  C, and vitamin B12

o Thiamin  

▪ Malnourished, homeless, alcoholics  

o Vitamin C  

▪ Impoverished, alcoholics, older adults  

o B12

▪ Vegans, those on antacids, adults over 50, those with HCL in stomach issues  

• Be able to describe the steps involved in vitamin B12 absorption, and the importance of stomach acid and  intrinsic factor  

1. B12 is bound to proteins in food

2. Stomach secretes intrinsic factor  

3. In the stomach, B12 is cleaved from food protein  

4. In the small intestine, intrinsic factor attaches to B12 – required for absorption  5. B12 is absorbed in the terminal ileum- final section of small intestine

Vitamin Names and Forms: Cheat Sheet

Most Common Name

Other Names

Vitamin E

Tocopherol and Tocotrienol (there are alpha, beta, gamma, and  delta forms of each)

Vitamin K

Phylloquinone, Menaquinone, Menadione

Vitamin D

Ergocalciferol, Cholecalciferol, Calciol, Calcidiol, Calcitriol

Vitamin A (pre-formed)

Retinol, Retinal, Retinoic acid

Pro-vitamin A carotenoids

Beta-carotene, alpha-carotene, beta-cryptoxanthin

Thiamin

Vitamin B1

Coenzyme form: TPP

Riboflavin

Vitamin B2

Coenzyme form: FMN, FAD

Niacin

Vitamin B3

Coenzyme form: NAD

Vitamin C

Ascorbic acid, Ascorbate

Folate

Folic acid (synthetic form)

Vitamin B12

Coenzyme forms: Methylcobalamin, 5-deoxyadenosylcobalamin

Pantothenic acid

Coenzyme form: Coenzyme A

Vitamin B6

Pyridoxal, Pyridoxine, Pyridoxamine  

Coenzyme form: Pyridoxal phosphate (PLP)

Choline

Neurotransmitter form: Acetylcholine

Vitamins Summary Sheet  

 

Vitamin

Fat- or  

Water

soluble?

Food Sources

Functions

Deficiency  

Diseases/Conditions

Toxicity  

Diseases/Conditions

Vitamin E

Fat

Soluble

-Plant Oils

-Salad dressing  

-Margarine  

-Whole grains  

-Nuts and seeds

Antioxidant  

- Located in the cell membrane protects  from oxidation

-Rare  

-Peripheral nerve  

degeneration  

- Hemolytic anemia (pre term infants)

Relatively non-toxic  

-May impair blood clotting

Vitamin K

Fat

Soluble

-Green vegetables  

-Liver, milk, eggs

-Blood clotting  

-Required for several steps in clotting pathway  -Facilitate carboxylation reactions

-Bleeding/impaired  

clotting  

-Abnormal bone formation  -Standard vitamin k  

injection for newborns

Rare

Vitamin D  

(calciferol)

Fat

Soluble

-Sunshine  

-Natural food sources: eggs, liver, fatty  fish, butter

-Fortified foods: milk, cereal

O Brain and nerve cells

- Protects against cognitive decline

- Slows progression of Parkinson’s disease O Muscle cells

- Encourages muscle growth in children - Preserves muscle strength in adults

O Immune cells

- Signals immune cells to fight against infectious  disease

O Adipose cells

- May regulate adipose cells and influence the  development of obesity

- aids in Calcium Absorption  

O Increases the amount of transport proteins  on the intestinal membrane  

o Increases the amount of calbindin  

- A protein that binds calcium inside the  intestinal cells

Rickets  

- Reduced bone  

mineralization in children  - Bowed legs and beaded  ribs  

Osteomalacia  

- Softening of the bones  - Increased fracture risk  Osteoporosis

O Hypercalcemia  

- Calcium deposits  

•Heart, kidney, blood  

vessels

Most likely of the vitamins  to have toxic effects when  consumed in excess

Vitamin A

Fat

Soluble

o Retinoids  

- Liver, fish oils, eggs  

- Milk and fortified cereals  

o Carotenoids  

o Vegetables  

- Dark green, orange/deep yellow  o Some  

fruits

o In foods

o Retinoids (in animal foods) primarily  retinyl esters

o In the body

o Retinol- supports reproduction

o Retinal- participates in vision

-Maintenance of the cornea  

-Component of rhodopsin protein in rod cells  that converts light impulses to nerve impulses -Important for night vision and adjustment to  changes in lighting  

o Retinoic acid – regulates growth

-Growth and bone Development

-Immunity

Antioxidant (carotenoids only)

-Night Blindness  

-Permanent blindness  

(xerophthalmia)

-Growth Stunting  

-Keratinization of tissues  -Reduced disease  

resistance  

*severe in parts of Africa &  Latin America

Retinoids only  

-Liver, bone, eye damage  possible  

-Birth defects  

Carotenoids are non-toxic  but could turn you a  

yellowish-orange

Vitamin

Fat- or Water

soluble?

Food Sources

Functions

Deficiency Diseases/Conditions

Toxicity  

Diseases/Conditions

Thiamin

Water-Soluble

-Whole & enriched grains

-Pork – best source  

-Soy milk

-Acorn squash

-Tomato Juice

Coenzyme (thiamin  

pyrophosphate)

Metabolizes energy

Beriberi

o Dry-damage to nervous systems  characterized by muscle weakness  in arms & legs

o Wet-damage to cardiovascular  system characterized by dilated  

blood vessels, edema

None

Riboflavin

Water-Soluble

-Milk & milk products

-Whole & enriched grains

-Egg

-Liver

-Dark green leafy vegetables

Coenzyme: FMN (Flavin  

mononucleotide) and FAD  

(Flavin adenine dinucleotide) - Antioxidant  

- Glutathione reductase

- inflammation of membranes of  the mouth, skin, eyes, and GI  

tract

None

Niacin

Water-Soluble

-Meat, poultry, fish (protein rich  foods)

-Legumes  

-Enriched & whole grains  

-Mushrooms, potatoes, tomatoes

-Coenzyme: NAD (nicotinamide  adenine dinucleotide)

-Energy transfer reactions

metabolism of fat, glucose, and  alcohol

-Carries hydrogens and electrons  during metabolic reactions to  the electron transport chain -DNA Repair

- Pellagra causing diarrhea, dermatitis,  dementia, and eventually death (4 D’s)

Niacin flush (~4X RDA)

Pantothenic  

Acid

Water-Soluble

Widespread in foods

Synthesizes:

- Cholesterol  

- Neurotransmitters

- Steroid hormones  

- Hemoglobin

Extremely rare  

Seen only in severe malnutrition

Vitamin

Fat- or Water

soluble?

Food Sources

Functions

Deficiency Diseases/Conditions

Toxicity Diseases/Conditions

Biotin

Water-Soluble

-Energy metabolism  

- Fatty acid metabolism  

-Gluconeogenesis

-Amino acid metabolism  

-DNA transcription

-Biotinidase deficiency (hereditary  disorder)

o Inability to recycle biotin

-High intake of raw egg whites

- Protein avidin binds biotin

- 12-24 per day for many weeks

-Deficiency during pregnancy is  

associated with birth defects

o Hair loss

o Scaly red rash  

o Neurological symptoms

Unknown

Vitamin B6

Water-Soluble

-Meats

-Legumes

-Whole grains

-Bananas

-Leafy vegetables

-coenzyme for over 100 enzymes  O Coenzyme form- Pyridoxal  

phosphate (PLP)

⮚ coenzyme for over 100 enzymes  o Coenzyme form- Pyridoxal  phosphate (PLP)

o Impaired protein and nucleic acid  synthesis  

▪ Skin lesions  

▪ Immune dysfunction  

▪ Growth failure  

o Inability to synthesize heme  

▪ Anemia  

o Inability to synthesis certain  

neurotransmitters  

▪ Seizures

o High potential for  toxicity, compared to  

most water-soluble  

vitamins

o Carpal tunnel  

syndrome, depression

o Irreversible nerve  

damage

Folate

Water-Soluble

⮚ Folate: leafy greens,  asparagus, orange juice  

⮚ Folic acid: white bread,  cereals

⮚ Accepts/ donates 1 C groups o Synthesis of DNA (cell  

division)

o Metabolism of amino acids o Maturation of red blood  

cells

o Activation of B12 coenzyme

⮚ Megaloblastic/ Macrocytic anemia  o Large, immature red blood  

cells  

o Nucleated  

o Low oxygen carrying capacity  ⮚ Neural tube defects (birth defects) ⮚ Spina bifida, anencephaly  

⮚ Increases blood homocysteine  levels

Vitamin B12

Water-Soluble

Animal Products only  

-Meat

-Cheese

-Eggs

-Seafood

-Liver

Coenzyme

⮚ Megaloblastic/macrocytic anemia  ⮚ Increased risk for heart disease and  stroke  

⮚ Supplements of folate will cure the  anemia… BUT the B12 deficiency  will still exist  

o High doe folic acid will  

prevent/cure the anemia  

and mask the B12  

deficiency but nerve  

damage will continue  

⮚ Neurological damage  

o Destruction of myelin  

sheaths  

o Memory loss, fatigue  

o Paralysis  

o Death

Vitamin

Fat- or Water

soluble?

Food Sources

Functions

Deficiency Diseases/Conditions

Toxicity Diseases/Conditions

Choline

Water-Soluble

o Found in most foods  that contain triglycerides - Especially high in egg  yolk, meats, peanut, and  liver

- Another good source  (that is lower in fat) is  

cauliflower

-Essential nutrient  

-Component of all cell membranes &  neurotransmitter acetylcholine

o Mild Deficiency  

o Mental impairment  

o More severe deficiency  

o Kidney dysfunction  

o Excess fat in liver  

o Pregnancy  

o Adequate intake of choline  

can cut risk of serious  

spinal defects in half.

o –There is some evidence  

that it also may improve  

cognition and memory in  

offspring

- High intakes lead to  vomiting, diarrhea,  

anorexia, salivation,  

and sweating

Vitamin C

Water-Soluble

⮚ Fruits  

o Citrus,  

strawberries,  

kiwi

⮚ Vegetables  

o Red pepper,  

tomatoes  

potatoes  

broccoli

⮚ Antioxidant  

⮚ Coenzyme  

o Synthesis of  

neurotransmitters,  

hormones, bile acids  

⮚ Collagen synthesis  

o Hydroxylation of proline  

and lysine (amino acids)

⮚ Promotes iron absorption

⮚ Scurvy  

o Weakness

o Pinpoint skin hemorrhages

o Bleeding gums

o Poor wound healing

o Rough, scaly skin

o Bone softening

o Anemia

- diarrhea/ GI  

disturbances

Week 10 Fat Soluble Vitamins (A)

March 15, 2017

I. Vitamin A

A. Retinoids

o Pre- formed vitamin A

o Retinol (alcohol form), Retinal (aldehyde form), Retinoic acid (acid form)

B. Pro- Vitamin A Carotenoids (precursors)  

o Β (beta) -carotene

o 1/12 of the Vitamin A activity of retinol

o 12 mcg β-carotene = 1 mcg retinol

o Α (alpha) -carotene

o 1/24 of the Vitamin A activity of retinol

o 24 mcg α-carotene = 1 mcg retinol

o β-cryptoxanthin

o 1/24 of the Vitamin A activity of retinol

o 24 mcg β-cryptoxanthin= 1 mcg retinol

C. Carotenoids with no Vitamin A Activity  

o Lutein and zeaxanthin (abundant in dark leafy greens) are the only carotenoids found in the retina and  lens of the eye; may help slow age-related macular degeneration and cataracts

o Lycopene (abundant in tomatoes and tomato products) may help prevent prostate cancer, much more  bioavailable when processed  

D. Food Sources  

o Retinoids  

o Liver, fish oils, eggs  

o Milk and fortified cereals  

o Carotenoids  

o Vegetables  

∙ Dark green, orange/deep yellow  

o Some fruits  

o Stable in cooking  

E. Absorption of retinol  

1. Retinol esters – retinol attached to a fatty acid  

2. Lipases separate retinol from fatty acid  

3. Free retinol must be reattached to fat  

4. Retinyl esters incorporated into chylomicron & travels through the lymphatic system to the liver  5. Retinol is separated then attached to retinol binding protein  

6. RBP attaches to TTR (transthyretin)  

F. Absorption of Carotenoids  

1. Carotenoids must be incorporated in micelles for absorption

2. Enterocyte  

3. Enterocytes incorporated into chylomicron

4. Chylomicrons enter the lymphatic system through the liver  

5. In the liver beta-carotene is split in half into Retinal  

6. Retinal is converted into retinol  

G. Functions  

o In foods

o Retinoids (in animal foods) primarily retinyl esters

o In the body

o Retinol- supports reproduction  

o Retinal- participates in vision  

o Retinoic acid – regulates growth  

H. Recommended Intake  

o RDA

o Adults 19-30 yrs

▪ Females = 700 μg RAE/day

▪ Males = 900 μg RAE/day

▪ RAE = Retinol Activity Equivalents

o Retinoids  

o 1 μg retinol = 1 RAE

o Precursor Vitamin A

o 12 μg beta-carotene = 1  

μg retinol = 1 RAE

I. Food sources  

J. Mechanism of Action  

o Regulation of gene expression  

o Enters cells and binds to  

receptor  

∙ Binds to DNA

o Controls gene expression  

(transcription)

o Regulates protein synthesis and  

cell differentiation  

K. Functions

o Vision (retinal)

o Maintenance of the cornea

o Component of rhodopsin  

▪ Protein in rod cells  

▪ Converts light impulses to nerve impulses  

o Important for night vision and adjustment to changes in lighting  o Integrity of skin and membranes  

o Retinoic acid  

▪ Prescription very potent, over the counter not as potent  o Growth and Bone development  

o Cell differentiation  

▪ Red blood cells

o Bone growth remodeling  

o Immunity  

o Maintains health of epithelial tissue  

o Antioxidant  

o Carotenoids only  

L. Deficiency  

o Night blindness

o Permanent blindness (xerophthalmia)

o Keratinization (hardening) of tissues  

o Growth stunting  

o Reduced disease resistance

o Severe in parts of Africa and Latin America  

M. Toxicity  

o Retinoids only  

o Liver, bone, eye damage possible

o Birth defects  

o UL= 3,000 mcg/day from retinoid forms of Vitamin A

o Carotenoids are non-toxic (no UL) but could turn you a yellowish- orange

Week 10: March 13, 2017

Fat Soluble Vitamins 1 (E, K, D)  

A. Fat-Soluble Vitamins (A, D, E, K)

- Absorption  

o Carried with dietary fats via chylomicrons  

o Require fat for absorption  

- Storage  

o Stored in the liver, adipose tissue  

- Handling and cooking losses

o Less vulnerable to loss that water

soluble vitamins, more stable  

B. Vitamin E

o Collective term for a family of related  

substances

o 4 tocopherols and 4 tocotrienols  

▪ Characterized as alpha,  

beta, gamma, or delta  

- Food sources  

o Plant oils  

o Salad dressing  

o Margarine  

o Whole grains  

o Nuts and seeds  

o Vulnerable

▪ Heat  

▪ Oxidation  

- Function  

o Antioxidant  

▪ Located in the  

cell membrane

▪ Protects cell  

membranes and  

other lipids  

from oxidation  

∙ Lungs, blood cells, eyes, liver, breast, muscle  

∙ Lipoproteins

- Recommended

Intake  

o RDA- Adults 15 mg/day  

o Deficiency  

▪ Rare

▪ Peripheral nerve degeneration

▪ Hemolytic anemia (preterm infants)

o Premature Infants transition to life outside the womb cause a drastic decrease in  EPO synthesis causing a decrease in RBC production and a shorter lifespan  

o RBCs in the pre-term infant are fragile, and highly susceptible to free radical damage o High rate of oxidation of polyunsaturated fatty acids in cell membrane causing  hemolysis  

- Toxicity  

o Excess intake (UL = 1000 mg/d)

▪ Relatively non- toxic  

▪ High doses may interfere with vitamin k  

∙ May impair blood clotting  

▪ Supplements use not currently recommended, due to cardiovascular concerns  - Effects on the Heart  

o Vitamin E- rich foods protect against LDL oxidation and therefore help to prevent/  slow down atherosclerosis  

o Reduces the risk of heart disease  

o What about supplements?  

▪ Have been associated with increases mortality, heart failure, and hemorrhagic  stroke  

▪ Not recommended  

C. Vitamin K  

- Forms of Vitamin K

o Phylloquinone (k1, plant sources)

o Menaquinones (MKs or K2 family, animals, bacteria)  

o Menadione (synthetic)  

- Vitamin K

o Production by intestinal bacteria  

▪ Menaquinone form  

▪ Available for absorption  

▪ Contribution relatively small, inadequate to meet needs  

- Recommended Intake

o No RDA  

o Adult Adequate Intake (AI) values  

▪ Females= 90 mcg/day  

▪ Males= 120 mcg/day  

- Food sources  

o Green vegetables  

o Liver, milk, eggs

o Resistant to cooking  

- Functions

o Blood clotting  

o Required for several steps in clotting  

pathway  

- Mechanism

o Facilitate carboxylation reactions  

▪ Carboxylation = adding CO2  

o This is how it works in blood clotting  

o Also, vital for bone protein synthesis

▪ Activation of osteocalcin and other proteins  

▪ Osteoblasts make the protein osteocalcin which must be carboxylated to be  able to bind to calcium  

- Vitamin K Recycling

o Vitamin K storage capacity is limited

o Therefore, the body recycles it to allow for multiple uses

o Two key enzymes required:

▪ Vitamin K- epoxide reductase  

▪ Quinone reductase  

- Deficiency  

o Bleeding/impaired clotting  

o Abnormal bone formation  

o Standard vitamin k injection for newborns  

- Toxicity  

o Rare  

o No UL has been established  

D. Vitamin D

o Also known as calciferol

- Forms of calciferol

o Vitamin ��2: ergocalciferol

▪ From plant foods in the diet

∙ Some mushrooms

o Vitamin ��3: cholecalciferol/calciol

▪ From animal foods in the diet

▪ From synthesis in the skin

- Synthesis  

o Occurs in skin  

o Stimulus= UV light  

o Precursor is made from cholesterol  

- Activation  

o Must be activated before they can fully function  

o Hydroxylation steps in liver and kidney  

▪ Adding of an –OH group  

- Active form of Vitamin D is a hormone

o Hormone:  

▪ Compound manufactured by one part of the body that travels though the blood  and causes another body part to respond  

o Vitamin D travels through the body and mainly targets:  

▪ Bones  

▪ Intestines  

▪ Kidneys  

- Vitamin D aids in Calcium Absorption  

o Increases the amount of transport proteins on the intestinal membrane  o Increases the amount of calbindin  

▪ A protein that binds calcium inside the intestinal cells  

- Other roles of Vitamin D

o Brain and nerve cells

▪ Protects against cognitive decline

▪ Slows progression of Parkinson’s disease

o Muscle cells

▪ Encourages muscle growth in children

▪ Preserves muscle strength in adults

o Immune cells

▪ Signals immune cells to fight against infectious disease

o Adipose cells

▪ May regulate adipose cells and influence the development of obesity - Sources of Vitamin D

o Sunshine

▪ Vitamin D synthesis

o Natural food sources:

▪ Eggs, liver, fatty fish, butter

o Fortified Foods:

▪ Fortified milk

▪ Fortified cereal

o Meeting recommendations is difficult without:

▪ Adequate sunshine, fortification, and supplementation

- Recommended Intake  

o RDA:

▪ 19-70 yrs: 15 μg/day or 600 IU/day  

▪ >70 yrs: 20 μg/day or 800 IU/day  

o UL:

▪ 100 μg/day or 4000 IU/day  

- Why do the elderly need more vitamin D  

o Older adults typically:  

▪ Drink little to no milk  

▪ Spend little time outdoors

o Lose capacity to make and activate Vitamin D with age  

- Vitamin D Deficiency  

o 10% of US are vitamin D deficient  

o Another 25% are marginally deficient  

o Factors that contribute to deficiency  

▪ Age  

▪ Darker skin  

▪ Breastfeeding without supplementation  

▪ Nott using fortified milk  

▪ Lack of sunlight  

∙ Wearing sunscreens

∙ latitude

o Causes a calcium deficiency

▪ Rickets  

∙ Reduced bone mineralization in children  

o Bowed legs and beaded ribs  

▪ Osteomalacia  

∙ Softening of the bones  

∙ Increased fracture risk  

▪ Osteoporosis  

- Vitamin D Toxicity  

o Hypercalcemia  

▪ Calcium deposits  

∙ Heart, kidney, blood vessels  

o Vitamin D is the most likely of the vitamins to have toxic effects when consumed in  excess  

▪ Be cautious with supplements

HUN2201 Week 11: Water Soluble Vitamins Overview

I. The Water-Soluble Vitamins  

A. Overview

⮚ Eight B-Vitamins  

o Thiamin (B1)

o Riboflavin (B2)

o Niacin (B3)

o Pantothenic acid (B5)

o B6

o Folate (B9)

o B12

o Biotin

⮚ Choline  

⮚ Vitamin C

o Water soluble vitamins are found in aqueous environments (e.g. cytoplasm of cells) o Primarily function as coenzymes

o In general, less potential for toxicity than fat-soluble vitamins, but there are exceptions o Toxicity rare with food, but can occur with supplements

B. Coenzymes  

⮚ Bind to and activate enzymes  

- Often carry electrons, atoms or molecules  

II. B1- Thiamin  

A. History  

⮚ 1st vitamin discovered  

⮚ 1911 Casimir Funk isolated a vital substance known at the time only as “anti-beriberi  factor”, and coins term the term “vitamine” (vital amine)

⮚ 1935 Robert Williams synthesizes the vitamin and names it thiamin (sulfur containing  vitamin)

o thiol = sulfur

B. Food Sources  

⮚ Whole & enriched grains

⮚ Pork – best source  

⮚ Soy milk

⮚ Acorn squash

⮚ Tomato Juice

C. Function- coenzyme  

⮚ Coenzyme form: TPP (thiamin pyrophosphate)

⮚ Energy metabolism

o Pyruvate ???? acetyl CoA

o Krebs Cycle: 5 carbon compound ???? 4 carbon compound

⮚ Nerve and muscle function

D. Deficiency  

⮚ Inadequate intakes reported among malnourished and homeless people, those who get  most energy from empty-calorie foods and beverages are also at risk

⮚ Alcohol contributes to deficiency

o 4/5 alcoholics are thiamin deficient

⮚ Deficiency disease: Beriberi

o Dry-damage to nervous systems characterized by muscle weakness in arms & legs

o Wet-damage to cardiovascular system characterized by dilated blood vessels,  edema

E. RDA  

⮚ Thiamin needs will be met if a person eats enough food to meet energy needs-if energy  is from nutritious foods.

⮚ Average thiamin intake meets or exceeds recommendations

⮚ Men: 1.2 mg/day

⮚ Women: 1.1 mg/day

⮚ *No adverse effects associated with excess thiamin and no UL has been determined III. B2- Riboflavin  

A. History  

⮚ 1932 Warburg and Christian isolated from yeast a substance that had a yellowish glow,  named it “yellow enzyme” which had a protein part and non-protein part (yellow part) ⮚ 1935 Paul Karrar isolates and crystallizes vitamin B2; recognizes it as the yellow enzyme B. Food Sources  

⮚ Milk & milk products

⮚ Whole & enriched grains

⮚ Egg

⮚ Liver

⮚ Dark green leafy vegetables

C. Function- Coenzyme  

⮚ Coenzyme forms: FMN (Flavin mononucleotide) and FAD (Flavin adenine dinucleotide) ⮚ Energy metabolism

o Accept and donate 2 hydrogens

o FAD picks up 2 hydrogens along with their electrons, from the Krebs cycle and  transports them to the electron transport chain

⮚ Antioxidant function

o Glutathione reductase

D. Deficiency  

⮚ Most often associated with other nutrient deficiencies

⮚ Causes inflammation of membranes of the mouth, skin, eyes, and GI tract

E. RDA

⮚ Most people in the US meet or exceed riboflavin recommendations

⮚ Men: 1.3 mg/day

⮚ Women: 1.1 mg/day

⮚ *No UL has been established and there are no known toxicity symptoms

IV. B3- Niacin  

A. History  

⮚ 1913 Casimir Funk isolates nicotinic acid from yeast; suggests that it is related to  vitamins B1 and B2

⮚ 1915 Goldberger demonstrates that pellagra is a dietary deficiency disease

⮚ 1937 Elvehjem isolates substance from liver called “pellagra preventing factor”,  identifies it as nicotinic acid

⮚ 1942 Nicotinic acid renamed “niacin”

B. Food sources  

⮚ Meat, poultry, fish (protein rich foods)

⮚ Legumes  

⮚ Enriched & whole grains

⮚ Mushrooms, potatoes, tomatoes  

C. Function- coenzyme  

⮚ Coenzyme form: NAD (nicotinamide adenine dinucleotide)

⮚ Energy transfer reactions-metabolism of fat, glucose, and alcohol

⮚ Carries hydrogens and electrons during metabolic reactions to the electron transport  chain

⮚ DNA Repair

o Prevents neurological degeneration

D. RDA

⮚ Can be biosynthesized from the amino acid tryptophan.

o ~60 mg of tryptophan = 1 mg niacin

⮚ Needs are in niacin equivalents (NE)

o Foods containing 1 mg niacin + 60 mg of tryptophan are 2 NE

⮚ Tryptophan could meet about ½ the daily niacin need for most people, but the average  diet easily supplies enough niacin

⮚ Men: 16 mg NE/day

⮚ Women: 14 mg NE/day

E. Deficiency

⮚ Pellagra causing diarrhea, dermatitis, dementia, and eventually death (4 D’s)

⮚ Originally thought to be an infection

⮚ Groundbreaking discovery that diseases could be caused by dietary deficiencies and not  only by infectious agents

⮚ In the early 1900’s pellagra caused misery and death to more than 87,000 people in the  Southern US. The diet was mainly low protein centered on corn.

F. Toxicity  

⮚ UL adults: 35 mg/day

⮚ Large doses (~4 times the RDA) from supplements can cause “niacin flush”

o Dilates the capillaries and causes tingling sensation that can be painful

V. Pantothenic Acid B5 

⮚ Energy metabolism  

o Part of coenzyme A

⮚ Synthesis of:

o Cholesterol  

o Neurotransmitters  

o Steroid hormones  

o Hemoglobin  

⮚ Recommended Intake  

o No RDA

o AI: Adults (19+):5 mg/d

o No UL

⮚ Food Sources  

o Widespread in foods  

o Readily destroyed by heat  

⮚ Deficiency  

o Deficiency is extremely rare

▪ Seen only in severe malnutrition

▪ Induced deficiency takes ~9 weeks in animal studies

∙ GI and nervous system effects

VI. Vitamin B6

⮚ Function-coenzyme for over 100 enzymes  

o Coenzyme form- Pyridoxal phosphate (PLP)

⮚ PLP-dependent enzymes function in synthesis of…

o NEAA (non-essential amino acids) by transamination

o Nucleic acids

o Niacin or neurotransmitters from tryptophan

o Hemeprecursor

⮚ Three forms found in the body (pyridoxal, pyridoxine, pyridoxamine)  o converted to PLP in the liver  

⮚ Food sources  

o Meats

o Legumes

o Whole grains

o Bananas

o Leafy vegetables

o Better absorbed from animal foods  

⮚ RDA

o Adults (19-50 yr):

▪ 1.3 mg/day (females and males)

o Increases with age/pregnancy/lactation

o Elderly (65+):

▪ Diets often low in B6

▪ Gets metabolized more quickly

▪ Recommendation: 2 mg/day

⮚ Deficiency  

o Impaired protein and nucleic acid synthesis  

▪ Skin lesions  

▪ Immune dysfunction  

▪ Growth failure  

o Inability to synthesize heme  

▪ Anemia  

o Inability to synthesis certain neurotransmitters  

▪ Seizures  

⮚ Toxicity (more potential for toxicity than other water soluble-vitamins  o UL = 100 mg/day

o High potential for toxicity, compared to most water-soluble vitamins o Carpal tunnel syndrome, depression

o Irreversible nerve damage

▪ 2-6 g/day (2000-6000 mg/day) for > 2 months

▪ Some damage at 500 mg/day

VII. Folate and Vitamin B12

A. Folate  

⮚ Accepts/donates 1 C groups

⮚ “One Carbon Metabolism”

–Synthesis of DNA (cell division)

–Metabolism of amino acids

–Maturation of red blood cells

–Lots of biological interaction with Vitamin B12!

B. Vitamin B12

⮚ Contains cobalt (unique)

⮚ Coenzyme forms

- Methylcobalamin

- 5-deoxyadenosylcobalamin

⮚ Methionine synthesis

⮚ –Methionine synthase enzyme (also requires folate)

⮚ Maintains myelin sheath of nerves

⮚ Lots of biological interaction with folate!

o Absorption  

▪ Complex

▪ Require adequate stomach acid, intrinsic factor (made in the stomach)

▪ Absorbed in terminal lumen  

1. B12 is bound to proteins in food  

2. Stomach secretes intrinsic factor  

3. In the stomach, B12 is cleaved from food protein  

4. In the small intestine, intrinsic factor attaches to B12 – required for  

absorption  

5. B12 is absorbed in the terminal ileum- final section of small intestine

VIII. Biotin  

⮚ Energy metabolism  

o Carboxylation reactions  

⮚ Fatty acid metabolism  

⮚ Gluconeogenesis  

⮚ Amino acid metabolism  

⮚ DNA transcription

⮚ The process of adding biotin is called “biotinylation”

⮚ The enzyme that facilitates this addition of biotin is called “holocarboxylasesynthase” ⮚ Pyruvate carboxylase is an example of an enzyme that requires biotin as a coenzyme A. Deficiency  

- Biotinidase deficiency (hereditary disorder)

■Inability to recycle biotin

- High intake of raw egg whites

■Protein avidin binds biotin

■12-24 per day for many weeks

- Deficiency during pregnancy is associated with birth defects

- Hair loss

- Scaly red rash

- Neurological symptoms  

B. Recommended intake  

⮚ No RDA

⮚ AI 30 mcg/day (adults)

⮚ Toxicity unknown  

⮚ Nutrient Interactions:  

o High dose pantothenic acid competes for absorption  

IX. Choline  

⮚ Recently deemed essential nutrient

⮚ Sometimes grouped with the B-vitamin family, although it’s not technically a B-vitamin ⮚ Component of

–All cell membranes

–Neurotransmitter acetylcholine

⮚ Donor of methyl groups (1 carbon units) in many metabolic reactions

A. Food sources  

o Found in most foods that contain triglycerides

o Especially high in egg yolk, meats, peanut, and liver

o Another good source (that is lower in fat) is cauliflower

B. Recommended Intake

o No RDA

▪ AI for adults = 425 mg (women), 550 mg (men)

–Pregnancy: 450 mg, Lactation: 550 mg

▪ –Average diets = 700-1,000 mg

o UL= 3500 mg

▪ High intakes lead to vomiting, diarrhea, anorexia, salivation, and sweating  

C. Deficiency  

o Mild Deficiency  

o Mental impairment  

o More severe deficiency  

o Kidney dysfunction  

o Excess fat in liver  

o Pregnancy  

o Adequate intake of choline can cut risk of serious spinal defects in half.

o –There is some evidence that it also may improve cognition and memory  

in offspring.

D. Effect of maternal choline status on brain function

o During late pregnancy, the hippocampus (memory center of the brain) is  

developing.

o Inadequate choline status during this critical period can have long term  

implications for brain structure and function.

o Animal Studies:

–Adult rodents typically experience a decline in memory with age, and a  

tendency toward senility.

–Multiple studies have confirmed that when pregnant rats are  supplemented with choline, their offspring did not become senile in their old  age.

Week 11 Water-Soluble Vitamins (Vitamin C, Folate, Vitamin B12)

March 22, 2017

I. Vitamin c  

⮚ Animals can synthesize their own vitamin c, guinea pigs, primates, and humans  cannot  

A. Functions

⮚ Antioxidant  

⮚ Coenzyme  

o Synthesis of neurotransmitters, hormones, bile acids  

⮚ Collagen synthesis  

o Hydroxylation of proline and lysine (amino acids)

⮚ Promotes iron absorption  

B. Food sources

⮚ Fruits  

o Citrus, strawberries, kiwi

⮚ Vegetables  

o Red pepper, tomatoes potatoes broccoli  

⮚ Vulnerable to:

o Heat/cooking, oxidation  

C. Factors affecting needs

⮚ Smoking  

⮚ Alcohol

o High levels of free radical damage deplete the body of Vitamin C  

D. Recommend Intake  

⮚ RDA

o Adults (19+)

o Females = 75 mg/day

o Males = 90 mg/day

o Average intake = 100-120 mg

o Smokers need more (+ 35 mg/day)

⮚ UL= 2000 mg/d  

o Toxicity: diarrhea/ GI disturbances  

E. Deficiency  

⮚ Scurvy  

o Weakness

o Pinpoint skin hemorrhages

o Bleeding gums

o Poor wound healing

o Rough, scaly skin

o Bone softening

o Anemia

⮚ Groups at risk  

o Impoverished

o Alcoholics

o Older adults

F. Vitamin C and the elderly  

⮚ Why it’s a concern  

o Some elderly populations have intakes well below the recommended  amount

o Preliminary research suggests older adults may have higher vitamin C  requirements

o Protection against oxidative damage becomes increasingly important  with age

II. Folate  

A. Nomenclature

⮚ Folate(s): naturally occurring form(s)

o Multiple glutamate groups  

o Enzyme in the intestinal tract cleaves all but one glutamate before  

absorption  

⮚ Folic acid: Supplements/ fortified foods  

o Synthetic form  

o Monoglutamate

B. Food Sources  

⮚ Folate: leafy greens, asparagus, orange juice  

⮚ Folic acid: white bread, cereals  

C. Functions  

⮚ Accepts/ donates 1 C groups

o Synthesis of DNA (cell division)

o Metabolism of amino acids

o Maturation of red blood cells

o Activation of B12 coenzyme

D. Deficiency  

⮚ Megaloblastic/ Macrocytic anemia  

o Large, immature red blood cells  

o Nucleated  

o Low oxygen carrying capacity  

⮚ Neural tube defects (birth defects)

⮚ Spina bifida, anencephaly  

⮚ Increases blood homocysteine levels

o Increases risk of atherosclerosis, heart disease, and stroke  

E. Folic Acid Fortification (1998)  

⮚ FDA Mandated Folic Acid Fortification  

o Neural tube defect reduction only reason for fortification  

▪ Incidence decreased by ~40%

o Enriched cereal grains  

▪ Flour, bread

▪ Rice, pasta

▪ Cornmeal  

▪ Snack products  

▪ Mixed dishes  

III. Vitamin B12

⮚ Contains cobalt (unique)  

⮚ Coenzyme forms

o Methylcobalamin  

o 5-deoxyadenosylcobalamin  

A. Deficiency  

⮚ Megaloblastic/macrocytic anemia  

⮚ Increased risk for heart disease and stroke  

⮚ Supplements of folate will cure the anemia… BUT the B12 deficiency will still exist  

o High doe folic acid will prevent/cure the anemia and mask the B12  deficiency but nerve damage will continue  

⮚ Neurological damage  

o Destruction of myelin sheaths  

o Memory loss, fatigue  

o Paralysis  

o Death  

⮚ Who’s at risk?

o Inadequate intake  

▪ Vegans  

o Inadequate B12 absorption

▪ Lack of HCL in stomach  

▪ People on antacid medications  

▪ Older adults over 50

B. Folate Supplementation  

⮚ Risk  

o May ask B12 deficiency  

⮚ UL: 1000 mcg folic acid (does not include food folate, which is not as readily  absorbed)

1. B12 is bound to proteins in food  

2. Stomach secretes intrinsic factor  

3. In the stomach, B12 is cleaved from food protein  

4. In the small intestine, intrinsic factor attaches to B12 – required for  absorption  

5. B12 is absorbed in the terminal ileum- final section of small intestine C. Vitamin B12 Transport, Storage, and Daily Needs  

⮚ Protein carrier = transcobalamin

⮚ RDA: 2.4 mcg/day

⮚ Liver storage: 5-12 mg

D. Food sources (animal products only)

⮚ Meat  

⮚ Cheese  

⮚ Fish  

⮚ Eggs  

⮚ Seafood  

⮚ Liver

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