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!