Chapter 6 Power Point

© 2016 Pearson Education, Inc.

Chapter 6 Lecture

Chapter 6:Vitamins: Micronutrients with Macro Powers

Learning Outcomes

1. Compare and contrast fat-soluble and water-soluble vitamins.

2. Explain the role of vitamin A in vision and cell differentiation, and its relationship to beta-carotene.

3. Identify the primary functions and food sources of vitamins D and K.

4. Discuss the process of oxidation and explain how it can damage cells.


Learning Outcomes

5. Discuss the interrelated roles of vitamins E and C in protecting cells from oxidation.

6. Explain how our body uses the B vitamins to generate energy.

7. Discuss the importance of adequate folate intake for women of childbearing age.


Learning Outcomes

8. Describe the interrelationship of vitamin B6, folate, and vitamin B12 in homocysteine metabolism and cardiovascular disease.

9. Explain how dietary supplements are regulated in the United States, and the recommendations for and against their use.

10.Discuss the three stages of cancer progression and the role of dietary factors in influencing cancer risk.


What Are Vitamins?

• Vitamins• Classified as micronutrients• Contain carbon• Essential in regulating multiple body

processes• May be fat-soluble• May be water-soluble


What Are Vitamins?


Fat-Soluble Vitamins

• Vitamins A, D, E and K• Are dissolvable in fat• Are absorbed in the intestine along with dietary

fat• Can be stored in the body



• Can build up to toxic levels• Megadosing of A and D can lead to death.

• Are found in fatty foods• Diet needs to contain the average amount

required over a period of time






Water-Soluble Vitamins

• Vitamin C and the B-vitamins group• Can be dissolved in water• Are absorbed easily through the intestinal wall• Can't be stored in large amounts in the body



• Rarely accumulate to toxic levels from diet alone• Supplements can lead to toxicity.• Should consume adequate amounts on a regular

basis






Preserving Vitamins

• Vitamins can be destroyed by:• Water• Heat• Light• Air• pH disturbances


Vitamin A Protects Our Sight

• Vitamin A is a fat-soluble vitamin.• The active form of vitamin A is retinol, found in

the retina of the eye.• Vitamin A is critical to maintaining healthy vision.






Click on the Vitamin a Visual Cycle link separate

from the power point.


• Functions of vitamin A• Essential for healthy vision• Cell differentiation: the process by which

cells mature and specialize• Development of T lymphocytes of the immune

system• Sperm production and fertilization• Bone growth




Click on the Vitamin a Epithelial link separate from the power point.

What Is the Role of Beta-carotene?

• Beta-carotene is: • in the class of chemicals called carotenoids• a provitamin

• Provitamins are inactive precursors that must be converted to active forms in the body.

• Beta-carotene is the precursor of retinol.


What Is the Role of Beta-carotene?

• Carotenoids like Beta-carotene are known to:• protect cell membranes against damage• enhance the immune system• protect skin from damage by UV light• protect eyes from damage



• Recommended intake• RDA is 900 micrograms/day for men;

700 micrograms/day for women.• Sources of vitamin A

• Obtained from animal sources (liver, eggs) and plant sources (dark green, orange, and deep yellow fruits and vegetables)




Vitamin A Toxicity

• Vitamin A is highly toxic, especially from single-nutrient supplements.

• Birth defects and permanent damage to the liver and eyes can result.


Vitamin A Deficiency

• Night blindness is the most common symptom of vitamin A deficiency.

• Other symptoms include:• Impaired immunity• Stunted bone growth• Reproductive system disorders• Increased risk for illness and infections• Blindness


Vitamin D Guards Our Bones

• Vitamin D• is a fat-soluble vitamin• can be synthesized by the body with

exposure to UV light from the sun• is a hormone since it is synthesized in one

location and acts in another location




Click on the Activation Vitamin D link separate from the power point.


• Functions of vitamin D• Required for calcium and phosphorus

absorption• Regulates blood calcium levels• Necessary for bone calcification



• Recommended intake• There is no RDA for vitamin D.• AI values range from 5 to 15 µg/day

depending on age and gender.• AI values assume that a person's sun

exposure is inadequate.• Extreme northern and southern latitudes

receive inadequate sun in the winter.• Vitamin D synthesis is decreased in older

adults and people with highly pigmented skin.



• Sources of vitamin D• Most foods naturally contain very little

vitamin D.• Most vitamin D is obtained from fortified foods

such as milk.• Vegetarians not consuming dairy foods

receive vitamin D from the sun, fortified soy products, and/or supplements.





• What if you consume too much vitamin D?• Can occur from vitamin supplements• Results in high blood calcium levels

• What if you don't consume enough vitamin D?• Rickets: occurs in children• Osteomalacia (soft bones): occurs in adults


Vitamin K Protects Against Blood Loss

• Vitamin K• is a fat-soluble vitamin stored in the liver• is required for blood coagulation• is a coenzyme: a compound that combines

with an inactive enzyme to activate the enzyme


Vitamin K: A Coenzyme



• Recommended intake• There is no RDA for vitamin K.• AI values are 120 µg/day for men and

90 µg/day for women.• Sources of vitamin K

• Green leafy vegetables, soybean and canola oils; also produced by intestinal bacteria





• What if you consume too much vitamin K?• No known side effects from large quantities

• What if you don't consume enough vitamin K?• Reduced blood clotting, excessive bleeding• Can occur with diseases that disturb

absorption of fat in the small intestine


What Are Antioxidants?

• Many metabolic processes involve oxidation reactions and can produce harmful free radicals.

• Antioxidants: chemicals that protect cells against damage from oxidation, including:• Vitamins E and C


Free Radical Formation


Click on the Free Radical Formation

link separate from the power point.

Formation of Free Radicals


Formation of Free Radicals

• Free radicals are highly unstable atoms.• Produced by oxidation reactions in cells• Also produced by pollution, ultraviolet light,

and toxic substances• Free radicals cause damage to:

• cell membranes• low-density lipoproteins (LDLs)• cell proteins• genetic material (DNA)

• Antioxidants work to stabilize free radicals.


Vitamin E Maintains Healthy Cells

• Vitamin E:• is a fat-soluble vitamin stored in fat tissue and

cell membranes• protects against free radical damage• protects LDLs, red blood cells, and cells lining

the lungs• is critical for development of muscles and

nerves



• Recommended intake• 15 mg per day

• Sources of vitamin E• Vegetable oils, nuts, seeds, wheat germ,

soybeans





• What if you consume too much vitamin E?• Vitamin E toxicity is uncommon.

• What if you don't consume enough vitamin E?• Vitamin E deficiencies are uncommon.• Can result in ruptured red blood cells, leading

to anemia


Vitamin C Protects Cells and Tissues

• Chemical name is ascorbic acid• Functions of vitamin C:

• Antioxidant• Re-energizes vitamin E• Protects against airborne pollutants• Synthesizes collagen• Prevents the disease scurvy• Enhances the immune system• Enhances absorption of iron



• Recommended intake• 90 mg/day for men; 75 mg/day for women• Smokers need an extra 35 mg/day.

• Sources of vitamin C• Fresh fruits and vegetables• Cooking destroys the vitamin C.





• What if you consume too much vitamin C?• Megadoses of vitamin C can cause nausea,

diarrhea, and nosebleeds.• What if you don't consume enough vitamin C?

• Scurvy is the most common vitamin C deficiency disease.

• Bleeding gums, loose teeth, weakness


B-Vitamins: The Energy Generators

• B-vitamins:• are water-soluble vitamins• are especially important for energy

metabolism• do not contain energy, but act as coenzymes

to help release energy from carbohydrates, fats, and proteins



• The B-vitamins are:

Thiamin (B1) Folate

Riboflavin (B2) Vitamin B12

Niacin Pantothenic acid

Vitamin B6 Biotin



• Thiamin (vitamin B1)

• Coenzyme required for carbohydrate metabolism

• Coenzyme for the metabolism of some amino acids

• Enriched foods and whole grains are good sources.

• Beriberi: deficiency of thiamin resulting in muscle wasting and nerve damage





• Riboflavin (vitamin B2)

• Part of coenzymes involved in protecting against oxidation damage

• Good sources of riboflavin include egg yolks, milk, enriched grain products.

• Ariboflavinosis: riboflavin deficiency; sore throat, swollen mucous membranes





• Niacin• Coenzyme assisting with metabolism of

carbohydrates and fatty acids• Good sources: meat, fish, poultry, enriched

bread products• Toxicity can result from supplements.• Pellagra: severe niacin deficiency





• Vitamin B6 (pyridoxine)

• Part of a coenzyme for more than 100 enzymes in protein metabolism

• Good sources: enriched cereals, liver, fish, poultry, starchy vegetables

• Toxicity from supplements can result in nerve damage, skin lesions.

• Deficiency may increase homocysteine in the blood.





• Folate• Involved in DNA synthesis and amino acid

metabolism• Critical for cell division of very early embryos• Good sources: ready-to-eat cereals, enriched

bread products

• Toxicity can mask vitamin B12 deficiency.





• Vitamin B12 (cobalamin)

• Part of coenzymes for blood formation• Required for nerve functioning• Required for homocysteine breakdown• Found only in animal-based foods• Deficiency results in low energy, fatigue,

shortness of breath.

• Pernicious anemia: B12 deficiency




Click on the Vitamin B12 link separate from the power

point.




• Pantothenic acid• Component of coenzymes for fatty acid

metabolism• Required for building new fatty acids• Good sources: chicken, beef, egg yolks,

potatoes, oat cereals, tomato products• No toxicity from excess pantothenic acid• Deficiencies are very rare.



• Biotin• Part of coenzymes involved in metabolism of

carbohydrates, fat, and proteins• Important for gluconeogenesis• Biotin content has been determined for very

few foods.• Biotin deficiencies are rare.


Choline

• Choline is a vitamin-like substance.• Assists in homocysteine metabolism• Accelerates the synthesis of acetylcholine, a

neurotransmitter• Good sources: milk, liver, eggs, peanuts• Deficiency can lead to liver damage.• Toxicity can result from supplements.


Dietary Supplements

• Are not strictly regulated• Who might benefit from vitamin/mineral

supplementation?• When can taking a vitamin/mineral supplement

be harmful?


Cancer

• Cancer: a group of related diseases characterized by cells that grow out of control.

• Composed of three steps:• Initiation • Promotion• Progression


Cancer

• Factors that increase cancer risk include:• tobacco use• sun exposure• nutrition• environmental/occupational exposure• low level of physical activity


Cancer


Cancer


Cancer


Cancer

• Antioxidants from whole foods may contribute to reducing the risk of cancer.

• Antioxidants from whole foods may work by:• enhancing the immune system• inhibiting growth of cancer cells• preventing oxidation damage to cells


Cancer

• Phytochemicals • Naturally occurring chemicals in plants• May reduce the risk of cancer, heart disease,

and stroke by reducing damage from free radicals

• Found in fruits, vegetables, whole grains, legumes, nuts, garlic, onion, soy products


Cancer


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Chapter 6 Power Point

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fatsoluble vitamins

b vitamins

sight vitamin

role of vitamin

water soluble vitamins

bvitamins group

vitamin b12