Download Nutrition Notes - 6

Chapter 6
Vitamins
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Learning Objectives
 1. State the general characteristics of
vitamins
 2. Identify the functions and food sources of
each of the 13 vitamins
 3. Identify which vitamins are most likely to
be deficient in the American diet and which
vitamins are most toxic
 4. List two health benefits of eating a diet rich
in fruits and vegetables
Learning Objectives (cont’d)
 5. Discuss the use of fruits and vegetables
on the menu
 6. Describe ways to conserve vitamins when
handling and cooking fruits and vegetables
 7. Give examples of functional foods and
discuss their role in the diet
 8. Define phytochemicals and give examples
of foods in which they are found
Characteristics of Vitamins
1. Very small amounts are needed by the body
and very small amounts are in foods
2. The roles they play in the body are very
important
3. Most vitamins are obtained through food.
Some are made by bacteria in the intestine
and one is made in the skin
4. There is no perfect food that contains all the
vitamins in the right amount
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Characteristics of Vitamins (cont’d)
5. Vitamins do not contain kcalories, but they
are involved in extracting energy from the
macronutrients
6. Some vitamins in foods are precursors
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Water-soluble vs. Fat-soluble vitamins
 Fat-soluble vitamins
 Vitamin A
 Vitamin D
 Vitamin E
 Vitamin K
 Water-soluble vitamins
 Vitamin C
 B-complex vitamins
such as thiamin,
folate, and B12
Fat-Soluble Vitamins
 Fat-soluble vitamins are generally found in foods
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containing fats and are stored in the body either in
the liver or in adipose tissue until needed
Excessive intake of A or D causes them to be stored
and can be undesirable. Vitamin D, when taken in
excess, is the most toxic of all the vitamins
Fat-soluble vitamins are absorbed and transported
around the body like other fats
If anything interferes with fat absorption, these
vitamins may not be absorbed
Low intake of vitamins A and E is a concern for
adults, children may have low intakes of vitamin E
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Forms of Vitamin A
Retinoids
Retinol
Retinal
Retinoic Acid
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Carotenoids
Beta-carotene
Retinol
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Functions of Vitamin A
 Essential for health of
the cornea (clear
membrane surrounding
eye)- deficiency causes
xerosis and eventually
xerophthalmia
 Essential for retina of
eye – deficiency causes
night blindness
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Functions of Vitamin A (cont’d.)
 Needed to make and maintain the epithelial
cells that form the protective linings of your
lungs, GI tract, and urinary tract
 Also essential to make and maintain epithelial
cells that produce mucus (protects cells)
 Role in reproduction, growth and
development, bone growth and teeth
developing in children
 Proper functioning of immune system
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Beta Carotene
 A precursor of vitamin A
 Functions as an antioxidant in the body – a
compound that combines with oxygen to
prevent oxygen from oxidizing or destroying
important substances
 Rich sources:
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Deep green vegetables – spinach
Deep orange fruits and veggies – carrots
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Retinol
 Preformed vitamin A
 Found in animal
products such as:
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Liver
Vitamin A-fortified milk
Eggs
Fortified cereals
Butter and margarine
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Measurement of Vitamin A
 Measured in retinol activity equivalents (RAE)
 One RAE =
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1 microgram retinol
12 micrograms beta-carotene
24 micrograms of other vitamin A precursors
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Vitamin A: Deficiency and Toxicity
 Deficiency is of most concern in developing
countries where it causes night blindness,
blindness, poor growth, and other problems
 Prolonged use of high doses of preformed
vitamin A may cause hypervitaminosis A
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Hair loss
Bone pain
Skin problems
Liver damage
Nausea/diarrhea
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Vitamin D
 When ultraviolet rays shine
on your skin, a cholesterollike substance is converted
into a precursor of vitamin D
and absorbed in the blood
 Over the next few days, the
precursor is converted to
vitamin D3 (cholecalciferol)
 Vitamin D3 is converted into
its active form – a hormone
– by enzymes in the liver
and then the kidney
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Functions of Vitamin D
 Maintains blood calcium levels by:
 Increasing calcium absorption in the intestine
 Decreasing the amount of calcium excreted
by the kidney
 Pulling calcium out of the bones
 Blood calcium levels must be kept high
so there is enough calcium to build bones
and teeth, contract muscles, and transmit
nerve impulses
 Bone growth
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Sources of Vitamin D
 Vitamin D fortified milk and cereals
 Fatty fish
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Vitamin D: Deficiency and Toxicity
 Deficiency in children: rickets
 Deficiency in adults: osteomalacia
 Toxicity: Vitamin D is most toxic of all
vitamins
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About 4 to 5x the Adequate Intake: symptoms
will include nausea, vomiting, diarrhea,
fatigue, and confusion; can lead to calcium
deposits in the heart, blood vessels, and
kidneys
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Functions of Vitamin E
 Antioxidant – especially helps the red blood
cells and cells in the lungs and brain
 May protect against heart disease by
preventing the oxidation of LDL
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Food Sources of Vitamin E
 Widely distributed in plant foods:
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Vegetable oils, margarine, and shortening
Salad dressing made from vegetable oils
Seeds and nuts
Whole-grain breads and cereals
Many Americans don’t consume enough vitamin E
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Vitamin K
 Essential role in producing blood-clotting
factors, such as prothrombin
 Needed to make an important protein used to
form bone
 Bacteria in the intestines produce a form of
vitamin K
 Food sources: liver, green leafy vegetables,
broccoli, vegetable oils
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Water-Soluble Vitamins
 Includes Vitamin C and B-complex vitamins
 B vitamins work in every cell as coenzymes
 Only small amounts of water-soluble vitamins
are stored in body (except B6 and B12)
 American adults take in too little vitamin C
 Excessive supplementation of certain watersoluble vitamins can cause toxic effects
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Functions of Vitamin C
 Needed to make collagen, a fibrous protein
that is part of skin, bone, teeth, ligaments,
and other connective structures. (Vitamin C
acts like Cement)
 Needed to make some hormones, such as
thyroxine
 Needed for immune system
 Antioxidant (like vitamin E and beta-carotene)
 Helps iron to be absorbed
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Vitamin C as an Antioxidant
Food Sources of Vitamin C
 Citrus fruits
 Bell peppers
 Kiwi fruit
 Strawberries
 Tomatoes
 Broccoli
 Potatoes
 Fortified juices and
cereals
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Vitamin C: Deficiency and Toxicity
 Deficiencies resulting in scurvy are rare
 Situations that require additional vitamin C:
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Pregnancy, lactation, growth, fever, infections,
burns, surgery, smoking
 UL is 2 grams: Over 2 grams causes
gastrointestinal symptoms. High levels
interfere with certain medical tests.
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Thiamin, Riboflavin, and Niacin
 All play key roles as part of coenzymes in
energy metabolism: they are essential to
release energy from carbohydrates, fats, and
proteins
 All are needed for normal growth
 Thiamin also plays a role in nerve function
 Riboflavin is needed to help form vitamin B6
coenzyme and to make niacin in the body
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Food Sources of Thiamin, Riboflavin,
and Niacin
 Thiamin – pork, sunflower
seeds, wheat germ, peanuts,
dry beans, whole-grain &
enriched breads/cereals
 Riboflavin – Milk & milk
products, organ meats,
whole-grain &enriched
breads and cereals
 Niacin – Meat, poultry, fish,
organ meats, whole-grain
and enriched breads and
cereals, peanut butter
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Tryptophan (Amino Acid) Found in Protein Foods is
Converted to Niacin in the Body
Amino Acid
Tryptophan
Niacin
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Functions of Vitamin B6
 Important role as part of a coenzyme involved
in carbohydrate, fat, and especially protein
metabolism
 To make hemoglobin
 Important to the immune system – WBCs
Also used to break down glycogen to glucose
and to make neurotransmitters
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Sources of Vitamin B6
 Meat, poultry, fish
 Not as well absorbed
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from plant foods
Potatoes
Some fruits (bananas
and watermelons)
Some leafy green
vegetables (broccoli
and spinach)
Fortified ready-to-eat
cereals
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Vitamin B6: Deficiency and Toxicity
 Deficiency: may occur in women and older adults
 Deficiency symptoms: fatigue, depression, irritability
 More than 2 grams daily for 2 months or more than
200 mg daily for longer can cause irreversible nerve
damage and symptoms such as numbness in hands
and feet and difficulty walking
 B6 is stored in the muscles
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Functions of Folate
 Part of coenzymes required to make DNA,
the genetic material contained in every cell
Therefore folate is needed to make all
new cells, especially those that need to be
replenished frequently:
RBC, WBC, and digestive tract cells
 Needed for amino acid metabolism
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Sources of Folate
 Green leafy vegetables
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(such as spinach)
Legumes
Orange juice
Fortified breads and
ready-to-eat cereals
Much folate is lost
during food prep and
cooking
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Dietary Folate Equivalents (DFEs)
 RDA for folate is measured in micrograms of
DFEs
 DFEs take into account the amount of folate
absorbed from natural and synthetic sources
 Synthetic folate is used in fortified foods such
as breads and in supplements
 Synthetic folate is absorbed at 1.7 times the
rate of naturally-occurring folate
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Folate Deficiency
 Deficiency causes megaloblastic anemia –
RDC are large and immature
 Other deficiency symptoms: digestive tract
problems such as diarrhea, mental confusion,
and depression
 During earliest weeks of pregnancy, women
need folate because a deficiency can cause
neural tube defects
 Some medications interfere with the normal
use of folate in the body
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Functions of Vitamin B12
 Convert folate into its active forms so that it
can make DNA
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Functions of Vitamin B12 (cont’d)
 Also functions as part of a coenzyme needed
to make new cells and DNA
 Helps in the normal functioning of the
nervous system by maintaining the protective
cover around nerve fibers
 Bone cells depend on vitamin B12
Sources of Vitamin B12
 Only animal foods.
Meat
 Poultry
 Fish and Shellfish
 Eggs
 Milk
 Milk Products
 Vegetarian
concerns
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Vitamin B12 Deficiency
 Deficiency is usually due to problem with
absorption – lack of intrinsic factor or lack of
hydrochloric acid – both are more so
problems as you get older
 Pernicious anemia develops when B12 is not
properly absorbed. Symptoms:
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Macrocytic anemia
Extreme weakness and fatigue
Nervous system problems – balance,
numbness, confusion
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Pantothenic Acid and Biotin
 Parts of coenzymes involved in energy
metabolism
 Pantothenic acid is also needed to make
lipids, neurotransmitters, and hemoglobin
 Biotin is also involved in the metabolism of
carbohydrates, fats, and protein
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Sources of Pantothenic Acid & Biotin
 Both pantothenic acid and biotin are
widespread in foods
 Pantothenic acid: Fortified cereals, beef,
poultry, mushrooms, potatoes, tomatoes
 Biotin: Egg yolks (Intestinal bacteria make
considerable amounts of biotin)
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Choline
 Choline can be made in the body in small
amounts
 Needed to make the neurotransmitter
acetylcholine and the phospholipid lecithin
(major component of cell membranes)
 Widespread in foods
 Choline is a conditionally essential nutrient
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Vitamin-like Substances
 Carnitine, lipoic acid, inositol, and taurine are
needed for normal metabolism but the body
makes enough so they are not vitamins.
Some are added to formula for infants
 Other substances promoted as vitamins, such
as pangamic acid or bioflavonoids, are clearly
not vitamins
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Ingredient Focus: Fruits & Veggies
 Low in kcalories
 Low or no fat (except
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avocados)
No cholesterol
Good sources of fiber
Excellent sources of
vitamins and minerals
Low in sodium (except
some canned veggies)
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Culinary Science
 Fruits and vegetables are mostly water
 Plant cells in picked fruits and vegetables
continue to be alive and take in oxygen for
breathing
 To slow down the breathing which causes the
fruit/vegetable to deteriorate, keep it cold and
moist
Culinary Science (cont’d)
 Cooking causes plant
cells to die, lose water,
and soften
 When cooking, you
need to control changes
in texture, flavor, and
color
Culinary Science (cont’d)
 How to control color changes
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Green vegetables
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Yellow/orange veggies
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Red veggies
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White veggies
Functional Foods and Superfoods
 Functional foods: Foods supplemented with
ingredients thought to help prevent diseases
or to improve health
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Margarine with an ingredient to lower
cholesterol
Drinks with herbs such as ginseng
 Phytochemicals: Substances such as beta-
carotene that are found largely in fruits and
veggies and that seem to be helpful in
preventing cancer and/or heart disease when
consumed regularly
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Superfoods
 Beans
 Nuts
 Cocoa
 Tea
 Spinach
 Plant stanols and sterols
Phytochemicals
Phytochemical Names
Good For
Food Sources
Lutein and Zeaxanthin
Healthy eyesight
Turnip, collard, and mustard
greens; kale; spinach; lettuce;
broccoli; green peas; kiwi;
honeydew melon
Indoles
Anti-cancer
Broccoli, cabbage, Brussels
sprouts, bok choy, arugula,
Swiss chard, turnips, rutabaga,
watercress, cauliflower, kale
Healthy heart,
healthy anti-cancer
Oranges, grapefruit, lemons,
tangerines, clementines,
peaches, papaya, apricots,
nectarines, pears, pineapple,
yellow raisins, yellow pepper
Green Vegetables & Fruits
Yellow/Orange Vegetable
& Fruits
Bioflavonoids
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Phytochemicals (cont’d)
Red Vegetables and Fruits
Anthocyanins
Healthy circulation,
healthy nerve
function, anti-cancer
Raspberries, cherries,
strawberries, cranberries, beets,
apples, red cabbage, red onion,
kidney beans, red beans
Anthocyanins
Healthy circulation,
healthy nerve
function, anti-cancer
Blueberries, purple grapes,
blackberries, black currants,
elderberries
Phenolics
Healthy cells, anticancer.
Raisins, prunes, plums, eggplant
Healthy immune
system, healthy
cholesterol levels,
anti-cancer
Garlic, onions, leeks, scallions,
chives
Blue/Purple Vegetables and
Fruits
White Vegetables and Fruits
Allium and Allicin
Source: National Cancer Institute
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