© 2011 McGraw-Hill Higher Education. All rights reserved. Understanding Nutrition and Your Diet...

© 2011 McGraw-Hill Higher Education. All rights reserved.

Understanding Nutrition and Your Diet

Chapter 5Chapter 5


NutrientsNutrients

• Nutrients = elements in food that are required for the growth, repair, and regulation of body processes1. Carbohydrates2. Fats3. Protein4. Vitamins5. Minerals6. Water7. Fiber


Energy from FoodEnergy from Food

Calorie = unit of energy1 calorie = amount of energy needed

to raise the temperature of 1 gram of water by 1 degree Celsius

In common usage, “calorie” refers to “kilocalorie” (1,000 calories)


CarbohydratesCarbohydrates

Major energy source: 4 calories/gramTypes

MonosaccharidesDisaccharidesPolysaccharides

Recommended intake: 45-65% of total calories from carbohydrates


CarbohydratesCarbohydrates

Simple sugars Average American adult consumes about

156 pounds of sweeteners each year Sugar, corn sweetener, syrup, honey Sodas, candy, bakery and processed goods

Sugar substitutes Saccharin Aspartame Sucralose, tagatose Sorbitol, xylitol Acesulfame potassium Neotame Stevia


FatsFats

Functions: Insulation, carrier of vitamins, storage of long-term energy, and satiety

Energy source: 9 calories/gram Types

SaturatedMonounsaturatedPolyunsaturatedTrans

Recommended intake: 20-35% of total calories


Types of FatsTypes of Fats

Saturated fats Solid at room temperature Primarily found in animal fats Negative effects on heart health

Monounsaturated and polyunsaturated fats Liquid at room temperature Vegetable oils Positive effects on heart health Omega-3 polyunsaturated fats found in fish are

considered especially healthful


Composition of Dietary FatsComposition of Dietary Fats


Types of Fats: Trans FatsTypes of Fats: Trans Fats

Altered form of unsaturated fat (hydrogen added)

Associated with unhealthy changes in cell membranes

Raises levels of “bad” cholesterol and lowers levels of “good” cholesterol

Found in margarine, snack foods, and some deep fried fast foodsCheck food labels


Types of Fats: CholesterolTypes of Fats: Cholesterol

White fatlike substance found in cells of animal origin

Functions: Synthesizes cell membranes; starting material in formation of hormones and bile

The liver can synthesize cholesterolExcess cholesterol in the body can

clog arteries and increase risk of cardiovascular disease


FatsFats

Low-fat does not necessarily mean low-calorie

Higher price tag Low-fat dairy and

salad dressings have less saturated fat

Simplesse, Olestra Fats cannot be

broken down and absorbed by body

Unpleasant side effects

Low-fat foods Fat substitutes


Fats: General Fats: General RecommendationsRecommendations

20-35% of total daily calories from fat Less than 10% of calories from

saturated fat Less than 300 mg/day of cholesterol Keep trans-fatty acid consumption as

low as possible Get most fats from sources of

unsaturated fats Fish Nuts Vegetable oils


ProteinProtein

Functions: Growth and maintenance of tissue, acid-base balance

Energy source: 4 calories/gramAmino acids = building blocks of

protein11 can be built by the body

Nonessential amino acids9 must be obtained from food

Essential amino acids


ProteinProtein

Complete protein sources supply all essential amino acidsAnimal foods, soybeans

Incomplete protein sources supply some but not all essential amino acidsPlant foods

Recommended intake: 10-35% of total calories


VitaminsVitamins

Organic compounds needed in small amounts for normal growth, reproduction, and maintenance of health

Serve as co-enzymes Provide no energy: 0 calories/gram Types

Water soluble B-complex vitamins and vitamin C

Fat soluble Vitamins A, D, E, K


Vitamins: Should I Take a Vitamins: Should I Take a Supplement?Supplement?

Following dietary recommendations would allow most Americans to meet their nutrient needs without supplements Many people eat too many nutrient-deficient foods

Caution with using supplementsHypervitaminosis = toxicity Megadoses of any vitamin can be harmful

Recommendations for certain groups Folic acid, vitamin B-12, vitamin D


PhytochemicalsPhytochemicals

Phytochemicals = physiologically active components of foods that may deactivate carcinogens

Many phytochemicals function as antioxidants May protect cells from damage caused by

unstable molecules (“free radicals”) Examples

Carotenoids Polyphenols Allyl sulfides


MineralsMinerals

Inorganic materials that act as structural elements and regulators of numerous body processes

Provide no energy: 0 calories/gramTypes

Macronutrients: “Major minerals” found in high amounts in the body

Micronutrients: “Trace elements” found in small amounts in the body


Water and FluidsWater and Fluids

Average adult loses about 10 cups of water per day Urination, bowel movements, breathing,

perspiration Functions: Provide medium for nutrients,

waste transport, temperature control For every pound of body weight, you need

about 0.5 ounce of fluid Sources: Beverages, fruits, vegetables


FiberFiber

Cellulose-based plant material that cannot be digested

Provides no energy: 0 calories/gram Types:

Soluble (gel-forming) Insoluble (absorbs water)

Benefits Moves stool through digestive tract Lowers blood cholesterol levels Steadies blood sugar levels

Recommended: 21-38 grams/day Most American adults: 11 grams/day


The Digestive System: The The Digestive System: The Absorption of NutrientsAbsorption of Nutrients


Tools for Planning a Tools for Planning a Healthy DietHealthy Diet

The USDA Food Guide: MyPyramid

The Dietary Guidelines for Americans


MyPyramidMyPyramid


MyPyramidMyPyramid

Personalized approachAmounts recommended from each food

group vary based on age, gender, and activity level

Visit www.mypyramid.govBalance food intake and physical

activity


MyPyramid Food GroupsMyPyramid Food Groups

Fruits 2 cups/day for a 2,000-calorie diet Eat a variety of fruits Favor whole fruits over fruit juices

Vegetables 2 1/2 cups/day for a 2,000-calorie diet Eat a variety of vegetables

Dark green vegetables Orange vegetables Legumes Starchy vegetables Other vegetables



Milk and milk products3 cups/day for a 2,000-calorie dietFavor fat-free or low-fat productsVegans and those who are lactose

intolerant should choose other sources of calcium



Meat, poultry, fish, eggs, dry beans, and nuts5 1/2 ounce-equivalents for a 2,000-

calorie diet1 ounce equivalents:

1 ounce cooked meat, poultry, fish1 egg1/4 cup legumes or tofu1 tablespoon peanut butter1/2 ounce nuts or seeds

Choose lean and low-fat foods



Breads, cereals, rice, and pasta6 ounces/day for a 2,000-calorie diet3 or more ounces/day should be whole

grains

1 ounce equivalents:1 slice bread1 cup dry cereal1/2 cup cooked rice, pasta, cereal



Oils (vegetable oils, fish, nuts, seeds)24 grams or 6 teaspoons/day for a 2,000-

calorie diet1 teaspoon equivalents:

1 teaspoon vegetable oil or margarine1 tablespoon low-fat mayonnaise2 tablespoons light salad dressing

Discretionary calories


Dietary Guidelines for Dietary Guidelines for AmericansAmericans

Focus on Nutrient DensityConsume nutrient-dense foods within and

among the food groupsWeight management

Balance calories from foods and beverages with calories expended

Make small decreases in calorie intake to prevent gradual weight gain over time



Physical activityRegular moderate physical activity

30 minutes/day to reduce risk of chronic disease

60 minutes/day to prevent gradual, unhealthy weight gain

60-90 minutes/day to sustain weight lossDecrease sedentary activities



Food groups to encourageFruitsVegetablesMilk



Foods to LimitFats, Sugars, Sodium, and Alcohol

FatsMost fat calories should come from

polyunsaturated and monounsaturated fats



Sugar consumptionChoose and prepare foods with little added

sugarSodium Intake

Sodium: Consume less than 2,300 mg/day (about 1 teaspoon of salt)

Too much sodium is linked to hypertension



Alcoholic beveragesThose who choose to drink should do so

sensibly and in moderationUp to 1 drink/day for womenUp to 2 drinks/day for men

Food safetyTake steps to avoid microbial foodborne

illness


Vegetarian DietsVegetarian Diets

Reliance on plant sources for most of the nutrients the body needs Ovovegetarian: Includes eggs Lactovegetarian: Includes dairy Ovolactovegetarian: Includes eggs and dairy Vegan: Excludes all animal products

Requires more planning Need to maintain adequate intake of vitamin B-12,

calcium, iron, zinc, vitamin D Semivegetarian: Great reduction (but not

elimination) of meat products Pescovegetarian: Includes fish, eggs, dairy products


Nutrition and the Older AdultNutrition and the Older Adult

Older adults may find food less tasteful, harder to chew

Lower energy requirementsPsychosocial factors

Social isolationDepressionAlcohol consumption Limited transportation


Food LabelsFood Labels

Required by the FDA since 1973

New in 2006Amount of trans fatProteins derived from

major food allergen sources


Nutrition Nutrition Facts LabelFacts Label


Fast FoodsFast Foods

Fat density of fast foods40-70% of calories in fast foods is fatRecommended intake: 20-35% of total

daily calories from fatMost people underestimate the

calorie content in a fast food meal


Functional FoodsFunctional Foods

Foods capable of contributing to the improvement or prevention of specific health problemsProbiotics: Living bacteria that help

prevent disease and strengthen the immune system (e.g., yogurt)

Garlic, olive oil, high-fiber foods, calcium-rich foods, antioxident-rich foods

Foods enriched with folic acid


Dietary SupplementsDietary Supplements

Products that supplement the total daily intake of nutrients in the diet

Ingested in tablet, capsule, softgel, gelcap, and liquid form

Not in themselves used as conventional foods or as the only items in a meal or diet

Must be deemed safe for human use Cannot claim to cure or prevent illnesses

Exceptions: Folic acid, calcium


Food AllergiesFood Allergies

Allergy = reaction in which the immune system attacks an otherwise harmless food or ingredient Different from a food intolerance, which is

usually caused by an enzyme deficiency Common food allergens include peanuts,

milk, soy products, shellfish, and wheat Allergic reactions can develop slowly over

several exposures Symptoms range from mildly unpleasant to

life threatening


Food SafetyFood Safety

Preventing foodborne illnessSafe handling,

cooking, and storage of foods



Food irradiationUse of radiation to kill foodborne

pathogensSafe farming techniques

More humane treatment of farm animalsImproved food qualityReduced exposure to antibiotic-resistant

bacteria, prions (cause of “mad cow disease”), and chemicals



Organic foodsNo use of growth

hormone or antibioticsNot genetically

engineered or irradiatedNo use of chemical

fertilizers or sewage sludge

Diseases, pets, and weeds treated or controlled primarily with nonchemical means



Food additivesProvide color or flavorImprove nutritional content, texture, or

shelf lifeFDA testedQuestionable additives: aspartame,

stevia, and some food coloringsGenetically modified foods

Altered to improve yields and reduce costs


Chapter Five: Chapter Five: Understanding Nutrition and Your DietUnderstanding Nutrition and Your Diet

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