2 Nutritional Needs

Objectives 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.

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

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

The Nutrients There are six main groups of essential nutrients: carbohydrates fats proteins vitamins minerals water © grafvision/Shutterstock © Elena Schweitzer /Shutterstock © shinyshot/Shutterstock © Helenlbuxton/Shutterstock © Kirsty Pargeter/Shutterstock © Jakub Pavlinec/Shutterstock continued

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

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

Dietary Supplements Besides supplements, fortified foods can be a source of added nutrients © Larisa Lofitskaya/Shutterstock

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 © Anatoliy Samara/Shutterstock

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

Sources of Carbohydrates © Cheryl E. Davis/Shutterstock © Seregam /Shutterstock © Drozdowski /Shutterstock Sugars, soft drinks, and candies are sources of simple carbohydrates Breads and cereals provide starches Fruits, vegetables, and whole grains offer fiber

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

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

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

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

Think Further Why don’t you need to add cholesterol to your diet? © Josh Resnick /Shutterstock

Functions of Fats Supply energy Carry certain types of vitamins Enhance flavor in foods Tenderize meats and baked goods Protect organs Insulate the body

Sources of Fats Eggs Dairy products Meats Fish Nuts Vegetable oils Olives Avocados © kiboka/Shutterstock

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

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

Functions of Proteins Growth, maintenance, and repair of tissues Formation of enzymes, some hormones, and antibodies Source of energy Regulation of bodily processes

Sources of Proteins Meat Poultry Fish Dairy products Eggs Dried beans Nuts © Liv friis-larsen/Shutterstock

Protein Deficiencies and Excesses A protein deficiency can lead to protein-energy malnutrition (PEM) Excess protein in the diet will be converted to fat

In Your Opinion… What is your favorite source of protein? © shadow216 /Shutterstock © ffolas /Shutterstock

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

Vitamins Fat-soluble vitamins Water-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

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

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 © Ildi Papp/Shutterstock continued

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

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 © Beneda Miroslav/Shutterstock

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 Is found in many fresh fruits and vegetables continued

Water-Soluble Vitamins B-complex vitamins work together in the body thiamin riboflavin niacin vitamin B6 folate vitamin B12 biotin continued

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 continued © Oliver Hoffmann/Shutterstock

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

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

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

Water-Soluble Vitamins Folate helps the body produce normal blood cells found in green vegetables, yogurt, fruits, and whole-grain cereals Folic acid is especially important during pregnancy © wavebreakmedia ltd/Shutterstock continued

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

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 © Monkey Business Images/Shutterstock

Vitamin Deficiencies and Excesses Vitamin deficiencies can result in such conditions and diseases as night blindness, rickets, scurvy, beriberi, pellagra, and anemia

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.

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

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 vegetables © Tarasyuk Igor/Shutterstock continued

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 © Joe Gough/Shutterstock continued

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

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

Trace Elements Iron Zinc 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

Trace Elements Fluoride Iodine helps teeth develop and resist decay may maintain bone health found in water Iodine helps regulate energy usage rate found in seafood and iodized salt © Philip Lange/Shutterstock

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 © Monkey Business Images/Shutterstock

Think Further Why do you need to vary your diet in order to consume the essential nutrients? © Bochkarev Photography/Shutterstock

Water Water is the sixth essential nutrient Between 50 and 75 percent of body weight is water © DUSAN ZIDAR/Shutterstock

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

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

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

Digestion and Absorption Foods must go through the processes of digestion and absorption before the body can use the nutrients they contain © Anton Albert/Shutterstock

The Digestive Tract The digestive or gastrointestinal tract is about 30 feet long esophagus stomach small intestine large intestine © Oguz Aral/Shutterstock

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

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

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

The Absorption Process Most absorption takes place in the small intestine The small intestine is lined with millions of villi, which aid in absorption © 3drenderings/Shutterstock

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

Metabolism During fat metabolism, fats become fuel During protein metabolism, amino acids are used for cell maintenance and growth or as energy

Review What are the six essential nutrients? carbohydrates fats proteins vitamins minerals water

Review 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?

Review 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 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