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