chapter images shutterstock.com 2 nutritional needs
TRANSCRIPT
CHAPTER
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2
Nutritional Needs
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• Name the key nutrients, describe their functions, and list important sources of each.
• Analyze the effects of various nutrient deficiencies and excesses.
• Explain the processes of digestion, absorption, and metabolism.
Objectives
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The Nutrients
• Food provides nutrients, which are necessary for good health
• Nutrition examines how the body uses nutrients
• If you do not eat the foods your body needs, you may suffer from malnutrition
continued
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The Nutrients
• Nonessential nutrients are substances the body can make
• Essential nutrients are substances the body cannot make and must be supplied by the foods you eat
continued
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The Nutrients
• There are six main groups of essential nutrients:1. carbohydrates
2. fats
3. proteins
4. vitamins
5. minerals
6. water
continued
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The Nutrients
• Failure to get enough of the needed nutrients may result in a deficiency disease
• Consuming too much of some nutrients can result in toxicity
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Dietary Supplements
• Doctors may recommend dietary supplements to help make up for nutrient shortages in the diet
• Some dietary supplements provide nonnutrient substances, such as herbs and some antioxidants
continued
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Dietary Supplements
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• Besides supplements, fortified foods can be a source of added nutrients
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Carbohydrates
• Carbohydrates are the body’s main energy source
• They are classified as simple or complex based on molecular structure
• They are carried through the bloodstream in the form of glucose
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Functions of Carbohydrates
• Carbohydrates are sources of energy for the body and brain
• Fiber does not provide energy, but can help– reduce the risk of heart disease– speed food through the body– dilute carcinogens (cancer-causing agents)– reduce the risk of cancer
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Sources of Carbohydrates
• Sugars, soft drinks, and candies are sources of simple carbohydrates
• Breads and cereals provide starches• Fruits, vegetables, and whole grains offer fiber
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Carbohydrate Deficiencies and Excesses• A carbohydrate deficiency can cause the
body to use protein as an energy source• This can interfere with the normal growth
and repair of body tissues and potentially create a chemical imbalance
• Consuming too many simple carbohydrates can result in nutrient shortages and excess calories
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Fats
• Fats belong to a group of compounds called lipids
• Lipids, which include both fats and oils, contain fatty acids
• Based on the amount of hydrogen atoms found in their molecules, fatty acids are classified as saturated or unsaturated
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Types of Fats
• Saturated fatty acids have as many hydrogen atoms as they can hold
• Unsaturated fatty acids have fewer hydrogen atoms than they can hold– monounsaturated– polyunsaturated
• Hydrogenation makes unsaturated fatty acids saturated and creates trans fatty acids
continued
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Types of Fats
• Cholesterol is a fatlike substance that serves important functions in the body– Part of skin tissue– Aids in transport of fatty acids– Produces hormones
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Think Further
Why don’t you need to add cholesterol to your diet?
Think Further
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Functions of Fats
• Supply energy• Carry certain types of vitamins• Enhance flavor in foods• Tenderize meats and baked goods• Protect organs• Insulate the body
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Sources of Fats
• Eggs• Dairy products• Meats• Fish• Nuts • Vegetable oils• Olives• Avocados
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Fat Deficiencies and Excesses
• A diet low in fat may result in a loss of weight and energy
• Diets high in fat have been linked to heart disease, some cancers, and weight gain– No more than 35 percent of the calories in your
daily diet should come from fat– No more than 10 percent of total calories should
come from saturated fat
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Proteins
• Proteins, the third category of essential nutrients, are made of amino acids– Essential amino acids– Nonessential amino acids
• Complete proteins contain all nine essential amino acids
• Incomplete proteins are missing one or more of the essential amino acids
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Functions of Proteins
• Growth, maintenance, and repair of tissues• Formation of enzymes, some hormones,
and antibodies• Source of energy• Regulation of bodily processes
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Sources of Proteins
• Meat• Poultry• Fish• Dairy products• Eggs• Dried beans• Nuts
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Protein Deficiencies and Excesses• A protein deficiency can lead to
protein-energy malnutrition (PEM)• Excess protein in the diet will be converted
to fat
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In Your Opinion…In Your Opinion…
What is your favorite source of protein?
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In Your Opinion…
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Vitamins
• Each vitamin serves unique functions• The body cannot produce most vitamins in
quantities large enough to meet nutritional needs
• A varied, nutritious diet is best to get the vitamins the body needs
continued
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Vitamins
Fat-soluble vitamins – vitamin A– vitamin D– vitamin E– vitamin K
Water-soluble vitamins– vitamin C – thiamin – riboflavin – niacin– vitamin B6
– folate – vitamin B12
– pantothenic acid– biotin
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Fat-Soluble Vitamins
• Vitamin A– aids the eyes with ability to see at night– promotes bone growth– keeps skin and other tissues healthy– found in liver, egg yolk, and whole milk– has higher values in orange and dark green
fruits and vegetables
continued
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Fat-Soluble Vitamins
• Vitamin D– promotes the growth
and mineralization of bones and teeth
– found in eggs, liver, and fatty fish
– used to fortify most milk, cereal, and margarine
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Fat-Soluble Vitamins
• Vitamin E– acts as an antioxidant– protects red and white bloods cells, fatty acids,
and vitamin A– common in many food items, including fats and
oils, whole-grain products, liver, eggs, whole milk dairy foods, and leafy green vegetables
continued
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Fat-Soluble Vitamins
• Vitamin K– aids in blood clotting– produced in the
intestinal tract– found in leafy green
vegetables, cauliflower, organ meats, and egg yolk
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Water-Soluble Vitamins
• Vitamin C (ascorbic acid)– helps form and maintain collagen, which holds
body cells together – firms the walls of blood vessels – helps heal wounds and broken bones– helps create hemoglobin and fight infections– functions as a dietary antioxidant– found in many fresh fruits and vegetables
continued
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Water-Soluble Vitamins
• B-complex vitamins work together in the body
– folate
– vitamin B12
– biotin
– thiamin– riboflavin– niacin
– vitamin B6
continued
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Water-Soluble Vitamins
• Thiamin (B1)– helps the body release energy from food and
promote normal appetite and digestion– found in nearly all foods except fats, oils, and
refined sugars
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Water-Soluble Vitamins
• Riboflavin (B2)– helps break down carbohydrates– helps cells use oxygen – keeps skin, tongue, and lips healthy– found in milk, eggs, oysters, leafy green
vegetables, and whole-grain enriched cereal products
continued
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Water-Soluble Vitamins
• Niacin–helps keep the nervous system, mouth, skin,
tongue, and digestive tract healthy–helps cells use nutrients–found in meats, poultry, and peanuts–too much niacin can cause nausea, vomiting,
and red flushing
continued
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Water-Soluble Vitamins
• Vitamin B6
– helps nerve tissues function normally– aids with the regeneration of red blood cells– helps break down proteins, carbohydrates,
and fats– found in vegetables, muscle meats, and whole-
grain cereals
continued
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Water-Soluble Vitamins
• Folate– helps the body produce
normal blood cells– folic acid is especially
important during pregnancy
– found in green vegetables, yogurt, fruits, and whole-grain cereals
continued
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Water-Soluble Vitamins
• Vitamin B12
– promotes normal growth
– aids in normal functioning of cells in bone marrow, nervous system, and intestines
– found in animal protein foods and cereals
• Pantothenic Acid– helps the body use
energy nutrients and make cholesterol
– promotes growth– found in plant and
animal tissues, yeast, and milk
continued
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Water-Soluble Vitamins
• Biotin– aids in the breakdown
of fats, carbohydrates, and proteins
– essential part of several enzymes
– found in kidney, liver, chicken, eggs, milk, fresh vegetables, and some fruits
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Vitamin Deficiencies and Excesses• Vitamin deficiencies can result in such
conditions and diseases as night blindness, rickets, scurvy, beriberi, pellagra, and anemia
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Did You Know?
The term vitamin was originally vitamine, a combination of the words vita and amine. Vita is Latin for life. Amine referred to amino acids, which scientists initially thought were part of the make up of vitamins. The final e was later dropped when scientists learned that vitamins did not contain amino acids.
Did You Know?
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Minerals
• The body needs at least 21 minerals for good health, which can be obtained from a variety of foods
• Macrominerals are needed in large quantities per day
• Trace elements, or microminerals, are needed in smaller quantities per day
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Macrominerals
• Calcium – combines with
phosphorous to build and strengthen bones and teeth
– helps blood clot– keeps the heart and
nerves working properly– found in milk, fish, and
green vegetablescontinued
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Macrominerals
• Phosphorous– works with calcium
to build bones and teeth
– helps the body store and release energy
– found in meat, poultry, eggs, milk, and dairy products
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Macrominerals
• Magnesium– helps regulate the body’s temperature– keeps the nervous system working properly– found in whole grains and grain products, nuts,
beans, meats, and dark green leafy vegetables
continued
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Macrominerals
• Sodium, chloride, and potassium– work as a team to control osmosis – help the nervous system and muscles function– help cells absorb nutrients– common in the food supply and U.S. diet– sources include table salt, many types of
seafood, many vegetables, and fruits
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Trace Elements
• Iron– helps form
hemoglobin, which carries oxygen throughout the body
– found in animal sources and leafy green vegetables
• Zinc– aids the immune
system– promotes normal
growth and development
– found in meats and whole grains
continued
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Trace Elements
• Iodine– helps regulate
energy usage rate– found in seafood
and iodized salt
• Fluoride– helps teeth develop
and resist decay– may maintain bone
health– found in water
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Mineral Deficiencies and Excesses
• Mineral deficiencies can cause such conditions as osteoporosis and goiter
• Research has shown there is a link between excess sodium amounts and hypertension
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Think FurtherThink Further
Why do you need to vary your diet in order to consume the essential nutrients?
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Water
• Water is the sixth essential nutrient
• Between 50 and 75 percent of body weight is water
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Functions of Water
• Water aids digestion, cell growth and maintenance, chemical reactions, joint lubrication, and temperature regulation in the body
• Nearly all beverages and foods provide some water
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Water Intake and Excretion
• About 80 percent of water intake comes from liquids
• The body excretes most water through the kidneys as urine and the remaining through the skin, lungs, and feces © Jakub Pavlinec/Shutterstock
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Water Requirements
• Most people should consume about 1 ounce of fluid for every 2 pounds of body weight
• Climate, health, and eating habits affect water needs
• Thirst is the first symptom of water loss• Too much water can result in water
intoxication, a rare condition
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Digestion and Absorption
• Foods must go through the processes of digestion and absorption before the body can use the nutrients they contain
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The Digestive Tract
• The digestive or gastrointestinal tract is about 30 feet long– esophagus– stomach– small intestine– large intestine
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The Digestion Process
• Mechanical phase– begins in the mouth when teeth chew food and
break it down into smaller pieces– initiates contractions in the digestive tract,
known as peristalsis
continued
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The Digestion Process
• Chemical phase– begins in the mouth when food mixes with
saliva– gastric juices break down food in the stomach– the semiliquid leaves the stomach and enters
the small intestine, where intestinal juices, pancreatic juices, and bile act on the food
continued
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The Digestion Process
– digestive enzymes help break foods down into simple substances the body can absorb and use
– once digestion is complete, absorption can take place
– some substances then travel into the large intestine, which acts as a reservoir
– the body excretes these materials in the feces
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The Absorption Process
• Most absorption takes place in the small intestine
• The small intestine is lined with millions of villi, which aid in absorption
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Metabolism
• Metabolism takes place in the cells after the body absorbs nutrients
• Nutrients follow a distinct metabolic path• Carbohydrates become glucose for energy
or glycogen for storage
continued
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Metabolism
• During fat metabolism, fats become fuel• During protein metabolism, amino acids are
used for cell maintenance and growth or as energy
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1. What are the six essential nutrients?1. carbohydrates
2. fats
3. proteins
4. vitamins
5. minerals
6. water
Review
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2. What is one function of each of the key nutrients?Answers will vary.
3. What are two important sources of each of the key nutrients?Answers will vary.
Review
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4. How can deficiencies and excesses of various nutrients affect the body?
nutrient deficiencies can result in deficiency diseases, protein-energy malnutrition, night blindness, rickets, scurvy, beriberi, pellagra, anemia, osteoporosis, hypertension, and goiter; nutrient excesses can result in toxicity
Review
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5. What occurs in the body during the processes of digestion, absorption, and metabolism?
digestion breaks food down into simple materials the body can use; absorption involves taking in nutrients and making them part of the body; metabolism involves chemical processes that take place in the cells after the body absorbs nutrients
Review