Vitamins - Napa Valley College

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Transcript Vitamins - Napa Valley College

Vitamins:
Vital Keys to Health
BIOL 103, Chapter 9
Today’s Topics
• Understanding Vitamins
• Fat Soluble Vitamins: A, D, E, K, and
Carotenoids
• The Water-Soluble Vitamins: Eight Bs and a C
• Bogus Vitamins
Understanding Vitamins
• Vitamins
– Needed in small amounts
– Not an energy source
– Individual units
– Organic compounds essential for normal
functioning, growth, and maintenance of the
body.
Understanding Vitamins
• Fat soluble vs. water-soluble
– Fat-soluble: vitamins A, D, E, K
• Absorbed with fat, with lymphatic system
• Stored in larger quantities
– Water-soluble: 8 B vitamins and vitamin C
• Absorbed into the bloodstream
• Stored in small amounts
– Which is more vulnerable to cooking losses?
Understanding Vitamins
• Food preparation affections vitamin content in
the foods
– Factors that determine amounts:
1.
2.
3.
4.
5.
6.
Source
Sunlight
Moisture
Growing conditions
Plant’s maturity at harvest
Packaging and storage
Understanding Vitamins
• Vitamins in foods
– Enrichment and fortification
• Enriched
• Fortified
• Some is required by law
– Provitamins
• Inactive forms of vitamins
Vitamin A: The Retinoids
• Functions
– Vision, cell development and health, immunity
• Food sources
– Preformed vitamin A: liver, milk, egg yolks
– Beta-carotene: yellow/orange fruits and vegetable
Forms of Vitamin A
• Three active forms of Vitamin A, collectively
known as Retinoids:
1. Retinol
2. Retinal
3. Retinoic acid
• Carotenoids: precursors of vitamin A
Functions of Vitamin A
1. Vision: night and day
– Night and color vision
– Becomes part of the retina
2. Cell production and differentiation
– Regulate production of enzymes, blood carrier
proteins, and structural proteins
– Cell differentiation
3. Skin
– Required to replace epithelial cells, which make
up epithelial tissues
Functions of Vitamin A (cont.)
4. Immune Function
– Produce immune cells to fight microorganisms
5. Reproduction
– Keeps reproduction tracts healthy
– Cell differentiation contributes to embryo
development during pregnancy
6. Bones
– Trigger an increase in osteoclasts; this contributes
to bone “remodeling”
Vitamin A
• Dietary Recommendations
– Retinol activity equivalent (RAE) = 1 ug retinol
• Uses RAE to account for differences between retinoids
and carotenoids
• Sources of vitamin A
– Animal: retinoids
– Plant: provitamin A carotenoids
– Fortified foods
Vitamin A Deficiency
1. Eyes
– Xerophtalmia
2. The skin and other epithelial cells
– Hyperkeratosis
3. Immune function
– Vulnerable to infection
4. Other effects:
– Growth retardation, bone deformities, defective
teeth, kidney stones
Vitamin A Toxicity
• Symptoms:
– fatigue, vomiting, abdominal pain, bone and joint pain,
loss of appetite, skin disorders, headache, blurred or
double vision, and liver damage
1. Teratogen
– Causes birth defects
2. Discoloration of skin
3. Acne Treatment:
– Retin-A and Accutane
The Carotenoids
• Plant pigments (deep yellow, orange, red
color)
• Can be converted to vitamin A
– Beta-carotene supplies the most vitamin A of the
carotenoids.
• Functions:
1. Vision
2. Lower risk of certain cancer
The Carotenoids
• Food sources:
– Orange/yellow fruit and
vegetables (tomatoes,
apricots, carrots), dark
green vegetables
– Absorb 20-40% of what
we eat
– Dietary fat and cooking
with heat (breaks down
cell walls) increases
absorption
Vitamin D
• Forms and formations:
– Activated in liver and kidney
• In the skin, UV light converts a form of cholesterol to D3
 to liver  dietary and synthesized forms of vitamin
D are converted to an intermediate form  goes to
kidneys  active form: 25-hydroxyvitamin D [25(OH)D]
or calcitrol
– Functions:
• Essential for bone health
• Regulate blood calcium levels
Vitamin D
• Sources:
– Sun exposure helps
activate an inactive form
of vitamin D
– Fortified milk
– Fortified food
• Question: Why would
manufacturers choose
milk to be fortified with
vitamin D?
Problem Set 9 Question #1
• Name at least three reasons why people
around the world will not have similar levels
of vitamin D.
Vitamin D
• Deficiency:
– In children:
• Rickets
– In adults:
• Osteomalacia or “soft bones”
• Osteoporosis
• Toxicity
– Hypercalcemia: a high concentration of calcium in
blood  excess deposit of calcium in soft tissues
• Fun Topic: Melanin and Tanning
Vitamin E
• Forms
– 8 similar compounds
• Essential: alpha-tocopherol
– Stored mainly in body fat
• Functions
– Antioxidant
• Protects cell membranes from free radicals
Vitamin E
• Food sources
– Nuts, seeds, vegetable oil, whole grain, wheat
germ oil, fruit, vegetables, and animal products
• Deficiency
– Occurs with fat malabsorption
– Rare genetic disorder
• Toxicity
– Nontoxic and adverse effects have not been found
– Can interfere with blood clotting
Vitamin K
• Forms:
– K1
– K2
• Functions:
– Blood clotting (also requires calcium)
– Bone formations
• Food sources;
– Green vegetables (spinach, broccoli, brussel
sprouts), plant oils, intestinal bacteria
Vitamin K
• Deficiency
– Rare in healthy people
– Newborn baby at risk
• Toxicity
– Can interfere with anticoagulant medications
– Toxicity is rare
Summary of Fat-Soluble Vitamins
The Water-Soluble Vitamins:
Eight Bs and a C
• Primarily coenzymes
• Antioxidants
• What to keep in mind about each vitamins:
– Function
– Food sources
– Toxicity vs. Deficiency
What is a Coenzyme?
• Coenzyme: a small compound that helps
enzymes in biochemical reactions. Most
coenzymes are derived from vitamins or are
made from vitamins.
Thiamin/B1
• Functions:
– Coenzyme in energy metabolism
– Part of the coenzyme: thiamin pyrophosphate
(TPP)
• Food sources:
– Pork, legumes, nuts and seeds, fish and seafood,
enriched grain product
– Cooking reduces content
Thiamin/B1
• Deficiency:
– Beriberi: overall profound muscle weakness and
nerve destruction
• “I can’t, I can’t”
– Q: Why would Beriberi be more common in
Southeast Asia?
• Toxicity:
– None reported
Riboflavin/B2
• Functions:
1. Coenzyme in energy metabolism (extracts energy
from glucose, fatty acids, and amino acids)
2. Supports antioxidants
• Food sources:
– Milk and dairy products
– Enriched grains, eggs
• Deficiency:
– Arbioflavinosis
• Toxicity: UL is not set
Niacin/B3
• Functions:
1. Coenzyme in energy metabolism
2. Supports fatty acid synthesis
• Food sources:
– Can be made from tryptophan
• Need B1, B6, and iron to convert to B3
– Whole and enriched grains
– Meat, poultry, fish, nuts, peanuts
Niacin/B3
• Deficiency:
– Pellegra: “rough skin”
• Four D’s: dermatitis, diarrhea, dementia, and death
– Can worsen if also deficient in B1, B6, and iron.
• Toxicity and medicinal uses
– High doses used to treat high blood cholesterol
– Side effects: skin flushing, liver damage
Pyridoxine/B6
• Functions:
1. Coenzyme in protein and amino acid metabolism
2. Supports immune system
3. Helps to lower blood levels of homocysteine  reduce
risk for heart disease
• Diagram:
• Food sources:
– Meat, fish, poultry, potatoes, bananas, sunflower seeds
Pyridoxine/B6
• Deficiency
– Microcytic hypochromic anemia
• Can also be caused by deficiency in iron.
• Toxicity
– Can cause subtle neurological damage
– Other symptoms: upset stomach, headaches,
sleepiness, tingling/prickling or burning sensation
Folate/B9
• Functions:
1. Coenzyme in DNA synthesis and cell division
2. Needed for normal red blood cell synthesis
3. Works with B6 and B12 to help control
homocysteine levels
• Food sources:
– Fortified cereals, enriched grains
– Green, leafy vegetables
Folate/B9
• Deficiency:
1. Megaloblastic anemia
2. Birth defects in the Neural Tube: Spina Bifida
3. Heart disease from elevated homocysteine levels
• Toxicity:
– Can mask vitamin B12 deficiency when you take folate
supplements
Cobalamin/B12
• “Cobalt-containing compounds” (cobalamin)
• Functions:
1. Needed for normal folate functions
•
•
DNA and red blood cell synthesis
Metabolize homocysteine
2. Maintains myelin sheath around nerves  nerves
protection
• Food sources:
– Only animal foods: meats, liver, milk, eggs
– Some fortified foods
Cobalamin/B12
• Absorption:
– Requires adequate stomach acid and intrinsic factor
• Deficiency:
– Can be caused by Pernicious anemia: autoimmune
disorder that damages stomach linings  reduced
B12 absorption
– Nerve damage
• Toxicity:
– No UL set
Pantothenic Acid/B5
• Function:
1. Component of coenzyme A
 extract energy from
nutrients and help build fatty
acids
•
Food sources:
– Widespread in foods
– Reduced by freezing, canning,
refining
• Deficiency/Toxicity: Rare
Biotin/B7
• Functions:
– Acts as a coenzyme in:
1. Amino acid metabolism (amino acids  glucose)
2. Fatty acid synthesis
• Food sources:
– Cauliflower, liver, peanuts, cheese
– Protein avidin (raw egg whites) binds biotin and
prevents absorption
• Deficiency and Toxicity are rare
Vitamin C
• Functions:
– Antioxidant
– Needed for collagen synthesis
– Enhances the absorption of iron from plant foods
• Food sources:
– Fruits: citrus, strawberries, kiwi
– Vegetables: broccoli, tomatoes, leafy green,
potatoes
Vitamin C
• Deficiency:
– Scurvy
• Toxicity:
– May cause GI distress
– For some people: kidney stones, iron toxicity
Summary of Water-soluble Vitamins
Choline: A Vitamin-Like Substance
• Function:
– Act as a catalyst to help metabolize homocysteine
• Food sources:
– Milk, liver, egg yolk, peanuts; overall is abundant
in food
• Deficiency: Unlikely in healthy people
• Toxicity:
– Diarrhea, falling blood pressure, fishy body odor
Bogus Vitamins
• Bogus vitamins: Unnecessary substances
found in some supplements
– Examples: hesperidin, para-aminobenzoic acid
(PABA), pangamic acid, rutin
– Think twice before you buy them!