Vitamins: Vital Keys to Health BIOL 103, Chapter 9.
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Transcript of Vitamins: Vital Keys to Health BIOL 103, Chapter 9.
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. Source 2. Sunlight3. Moisture4. Growing conditions5. Plant’s maturity at harvest6. 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 skin3. 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. Vision2. 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 metabolism2. 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 metabolism2. Supports immune system3. 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 division2. Needed for normal red blood cell synthesis3. Works with B6 and B12 to help control
homocysteine levels
• Food sources:– Fortified cereals, enriched grains– Green, leafy vegetables
Folate/B9
• Deficiency:1. Megaloblastic anemia2. Birth defects in the Neural Tube: Spina Bifida3. 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!