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NutritionNutrition
Nutritional Requirements: Nutritional Requirements: Components of a Healthy DietComponents of a Healthy Diet
Proteins Carbohydrates Fats Vitamins Minerals Water
Essential nutrients = substances the body must get from food because it cannot manufacture them at all or fast enough to meet its needs
Energy from FoodEnergy from Food
Three classes of essential nutrients supply energy
Kilocalorie = a measure of energy content in food; the amount of heat it takes to raise the temperature of 1 liter of water 1°C; commonly referred to as “calorie”
Sources of Energy in the Sources of Energy in the DietDiet
Proteins—The Basis of Body Proteins—The Basis of Body StructureStructure
Protein = a compound made of amino acids that contains carbon, hydrogen, oxygen, and nitrogen
Of twenty common amino acids in foods, nine are essential
Proteins form key parts of the body’s main structural components—muscles and bones—and of blood, enzymes, cell membranes, and some hormones
Complete and Incomplete Complete and Incomplete ProteinsProteins
Complete protein sources = foods that supply all the essential amino acids in adequate amounts Meat, fish, poultry, eggs, milk, cheese, and soy
Incomplete protein sources = foods that supply most but not all essential amino acids Plants, including legumes, grains, and nuts
Recommended Protein Recommended Protein IntakeIntake
Adequate daily intake of protein = 0.8 gram per kilogram (0.36 gram per pound) of body weight
Acceptable Macronutrient Distribution Range = 10–35% of total daily calories as protein
Fats—Essential in Small Fats—Essential in Small AmountsAmounts
Fats supply energy, insulate the body, support and cushion organs, absorb fat-soluble vitamins, add flavor and texture to foods
Essential fats (linoleic acid and alpha-linolenic acid) are key regulators of body process such as the maintenance of blood pressure and the progress of a healthy pregnancy
Types and Sources of FatsTypes and Sources of Fats Saturated fat = a fat with no carbon-carbon double bonds;
usually solid at room temperature Found primarily in animal foods and palm and coconut oils
Monounsaturated fat = a fat with one carbon-carbon double bond; usually liquid at room temperature Found in certain vegetables, nuts, and vegetable oils
Polyunsaturated fat = a fat with two or more carbon-carbon double bonds; usually liquid at room temperature Found in certain vegetables, nuts, and vegetable oils and
in fatty fish
Types and Sources of FatsTypes and Sources of Fats Two key forms of polyunsaturated fats:
Omega-3 fatty acids are produced when the endmost double bond of a polyunsaturated fat occurs three carbons from the end of the fatty acid chain
Found primarily in fish
Omega-6 fatty acids are produced when the endmost double bond of a polyunsaturated fat occurs six carbons from the end of the fatty acid chain
Found primarily in certain vegetable oils, especially corn, soybean, and cottonseed oils
Chemical Structure of FatsChemical Structure of Fats
Comparison of Dietary FatsComparison of Dietary Fats
Total Fat Content of FoodsTotal Fat Content of Foods
Fats and HealthFats and Health
Fats affect blood cholesterol levels
Low-density lipoprotein (LDL) = “bad” cholesterol
High-density lipoprotein (HDL) = “good” cholesterol
Saturated and trans fats raise levels of LDL; trans fats also lower levels of HDL
Unsaturated fats lower levels of LDL
Fats and HealthFats and Health
Fats also affect triglyceride levels, inflammation, heart rhythm, blood pressure, and cancer risk
Best choices = monounsaturated fats and polyunsaturated omega-3 fats
Limit intake of saturated and trans fats
Saturated and Trans Fats: Comparing Saturated and Trans Fats: Comparing Butter and MargarineButter and Margarine
0 5 10 15
Grams of fat in 1 tablespoon
Squeezemargarine
Tubmargarine
Margarinespread
Stickmargarine
Butter
Saturated fat
Trans fat
Other fats
SOURCE: Food an Drug Administration
Recommended Fat IntakeRecommended Fat Intake
Adequate daily intake of fat:
= about 3–4 teaspoons of vegetable oil Acceptable Macronutrient Distribution Range =
20–35% of total daily calories as fat
Carbohydrates—An Ideal Carbohydrates—An Ideal Source of EnergySource of Energy
The primary function of dietary carbohydrate is to supply energy to body cells.
Some cells, such as those in the brain, nervous system, and blood, use only carbohydrates for fuel
During high-intensity exercise, muscles get most of their energy from carbohydrates
During digestion, carbohydrates are broken into single sugar molecules such as glucose for absorption; the liver and muscles take up glucose and store it in the form of glycogen
Simple and Complex Simple and Complex CarbohydratesCarbohydrates
Simple carbohydrates contain one or two sugar units in each molecule Found naturally in fruits and milk and added to
many other foods Include sucrose, fructose, maltose, and lactose
Complex carbohydrates consist of chains of many sugar molecules Found in plants, especially grains, legumes, and
tubers Include starches and most types of dietary fiber
Whole GrainsWhole Grains
Before they are processed, all grains are whole grains consisting of an inner layer of germ, a middle layer called the endosperm, and an outer layer of bran
During processing, the germ and bran are often removed, leaving just the starchy endosperm
Refined carbohydrates usually retain all the calories of a whole grain but lose many of the nutrients
Refined Carbohydrates Versus Refined Carbohydrates Versus Whole GrainsWhole Grains
Whole grains are higher than refined carbohydrates in fiber, vitamins, minerals, and other beneficial compounds
Whole grains take longer to digest Make people feel full sooner Cause a slower rise in glucose levels
Choose foods that have a whole grain as the first item on the ingredient list on the food label Whole wheat, whole rye, whole oats, oatmeal,
whole-grain corn, brown rice, popcorn, barley, etc.
Recommended Carbohydrate Recommended Carbohydrate IntakeIntake
Adequate daily intake of carbohydrate = 130 grams
Acceptable Macronutrient Distribution Range = 45–65% of total daily calories as carbohydrate
Limit on intake of added sugars Food and Nutrition Board: 25% or less of total
daily calories World Health Organization: 10% or less of total
daily calories
Acceptable Macronutrient Distribution Acceptable Macronutrient Distribution Ranges: SummaryRanges: Summary
Protein = 10–35% of total daily calories
Fat = 20–35% of total daily calories
Carbohydrate = 45–65% of total daily calories
Fiber—A Closer LookFiber—A Closer Look
Dietary fiber = nondigestible carbohydrates and lignin that are present naturally in plants
Functional fiber = nondigestible carbohydrates isolated from natural sources or synthesized in a lab and added to a food or supplement
Total fiber = dietary fiber + functional fiber
Sources of FiberSources of Fiber
All plant foods contain fiber, but processing can remove it
Good sources of fiber: Fruits (especially whole, unpeeled fruits) Vegetables Legumes Oats (especially oat bran) Whole grains and wheat bran Psyllium (found in some cereals and
laxatives)
Recommended Intake of Recommended Intake of FiberFiber
Women = 25 grams per dayMen = 38 grams per day
Americans currently consume about half this amount
Vitamins—Organic Vitamins—Organic MicronutrientsMicronutrients
Vitamins = organic (carbon-containing) substances needed in small amounts to help promote and regulate chemical reactions and processes in body cells.
Four vitamins are fat-soluble (A, D, E, and K)
Nine vitamins are water-soluble (C and the eight B-complex vitamins: thiamin, riboflavin, niacin, vitamin B-6, folate, vitamin B-12, biotin, and pantothenic acid)
VitaminsVitamins
Vitamins are abundant in fruits, vegetables, and grains; they are also added to some processed foods
If you consume too much or too little of a particular vitamin, characteristic symptoms of excess or deficiency can develop
Vitamins commonly lacking in the American diet:
Vitamin A Vitamin B-6Vitamin E Vitamin C
MineralsMinerals
If you consume too much or too little of a particular mineral, characteristic symptoms of excess or deficiency can develop
Minerals commonly lacking in the American diet: Iron = low intake can cause anemiaCalcium = low intake linked to osteoporosisPotassium = low intake linked to elevated
blood pressure and bone mineral loss
Water—A Vital ComponentWater—A Vital Component
Human body is composed of about 60% water; you can live only a few days without water
Foods and fluids you consume provide 80–90% of your daily water intake
Adequate intake to maintain hydration: Women need to drink about 9 cups of fluid per day Men need to drink about 13 cups of fluid per day
Drink in response to thirst; consume additional fluids for heavy exercise
Should You Take Supplements?Should You Take Supplements?
The Food and Nutrition Board recommends supplements only for certain groups: Folic acid for women capable of becoming
pregnant (400 µg/day) Vitamin B-12 for people over age 50 (2.4 mg/day)
Other possible situations for supplements: Vitamin C for smokers Iron for menstruating women Vitamin K for newborns People with certain special health concerns
Canada’s Food GuideCanada’s Food Guide
Food LabelsFood Labels
Read labels to learn more about your food choices.
Dietary SupplementsDietary Supplements
May contain powerful bioactive chemicals
Not regulated the way drugs are by the FDA in terms of testing and manufacture
May interact with prescription and over-the-counter drugs and supplements
Dietary SupplementsDietary Supplements