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5: Nutrition

Your Health Today, 6th edition

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Understanding Nutritional Guidelines

Dietary Reference Intakes (DRIs): four sets of dietary recommendations

Suggested intake levels of essential nutrients for optimal health

Recommended Dietary Allowance (RDA): average daily amount of any one nutrient needed to protect against nutritional deficiency

Acceptable Macronutrient Distribution Range (AMDR): intake ranges of essential nutrients that provide adequate nutrition and reduce risk of chronic disease

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Understanding Nutritional Guidelines (2)

Dietary Guidelines for Americans: scientifically based diet and exercise recommendations

MyPlate: graphic nutritional tool that translates DRIs and Dietary Guidelines into healthy food choices, published by the USDA

Daily Values: standards used on food labels to indicate how a particular food contributes to the recommended daily intake of major nutrients in a 2,000-calorie diet

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Types of Nutrients

Essential nutrients: needed to build, maintain, and repair tissues and regulate body functions

Macronutrients: needed in large amounts

Water, carbohydrates, proteins, fats

Micronutrients: needed in small amounts

Vitamins, minerals

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Water—The Unappreciated Nutrient

Functions:

Digests, absorbs, transports nutrients

Helps regulate body temperature

Carries waste out of the body

Lubricates our body parts

Right fluid balance—the right amount of fluid inside and outside each cell—is maintained by electrolytes

Minerals that carry electrical charges and conduct nerve impulses

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Water—The Unappreciated Nutrient (2)

Water supply in the U.S. is generally well regulated and very safe

FDA regulates bottled water only if it is shipped across state lines

RDA for water:

1 to 1.5 milliliters per calorie spent

For 2,000 calories spent: 2 to 3 liters, or 8 to 12 cups of fluids

Water needs can vary depending on several factors, such as foods consumed and activity level

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Carbohydrates—Your Body’s Fuel

Body’s main source of energy

Fuel most of the body’s cells during daily activities

Used by muscle cells during high-intensity exercise

Only source of energy for brain cells, red blood cells, and some other types of cells

Divided into simple carbohydrates (sugars) and complex carbohydrates (starches and dietary fibers)

RDA for carbohydrates:

130 grams for males and females aged 1–70 years

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Simple Carbohydrates

Simple carbohydrates are easily digestible, and are composed of one or two units of sugar

Glucose, fructose, galactose, lactose, maltose, sucrose

Glucose travels to the liver, where it can be stored as glycogen for future energy needs

Sucrose (table sugar) scores 1.0 as the benchmark for sweetness

High fructose corn syrup (HFCS) also scores 1.0

Stevia sugar substitute: 300.0

Americans consume 22.5 teaspoons of sugar per day, mostly in sweetened beverages

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Simple Carbohydrates (2)

Too many simple carbohydrates leaves you with a “sugar high,” followed by a feeling of depletion and a craving for more sugar

Added sugars have been linked to the epidemic of overweight and obesity

Dietary Guidelines recommends less than 10% of calories come from added sugars

Artificial sweeteners are often touted as alternatives

May result in weight gain due to their effect on appetite and insulin response

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Complex Carbohydrates

Complex carbohydrates are composed of multiple sugar units and include starches and dietary fiber

Starches occur in grains, vegetables, and some fruits

Whole grains are preferred over refined carbohydrates (plant sources whose fiber has been processed away)

Provide more nutrients

Slow digestive process

Make you feel full longer

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Fiber

Dietary fiber: complex carbohydrate found in plants that cannot be broken down by the digestive tract

Allows for passage of food quickly through the intestines, which helps prevent hemorrhoids and constipation

Functional fiber: natural or synthetic fiber added to food

Total fiber: combined amount of dietary fiber and functional fiber

Soluble fiber dissolves in water and lowers cholesterol

Insoluble fiber passes through the digestive tract unchanged; serves as natural laxative

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Fiber (2)

RDAs for fiber:

25 grams/day for women (aged 19–50)

38 grams/day for men (aged 14–50)

Best obtained through diet, not pills or supplements

Good sources are fruits, vegetables, dried beans, peas and other legumes, cereals, grains, nuts, and seeds

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Protein—Nutritional Muscle

Functions of protein:

Build and maintain muscles, bones, and other body tissues

Form enzymes that facilitate chemical reactions

Constructed from 20 different amino acids

Essential amino acids: 9 amino acids the body cannot produce on its own, so they must be supplied by foods

Complete proteins have ample essential amino acids

Incomplete proteins contain small amounts or some of the essential amino acids

AMDR for protein: 10–35% of daily calories

0.36 grams per pound of body weight

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Protein—Nutritional Muscle (2)

Complete protein sources: animal proteins (meat, fish, poultry, milk, cheese, and eggs)

Incomplete protein sources: vegetable proteins (grains, legumes, nuts, seeds, and vegetables)

Complementary proteins: proteins that in combination provide essential amino acids

Mutual supplementation: nutritional strategy of combining two incomplete protein sources to provide a complete protein

For example, beans and rice

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Fats—A Necessary Nutrient

Fats are the body’s principal form of stored energy

Provide essential fatty acids

Help produce other fatty acids and vitamin D

Provide the major material for cell membranes and for the myelin sheaths that surround nerve fibers

Assist in absorption of the fat-soluble vitamins

Affect the texture, taste, and smell of foods

Provide an emergency reserve when we are sick or when our food intake is diminished

AMDR for fat: 20–35% of daily calories

Less than one-third from saturated fats and trans fats

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Types of Fat

Saturated fats: lipids that are the predominant fat in animal products and other fats that remain solid at room temperature

Beef

Pork

Poultry

Whole-milk dairy products

Certain tropical oils (coconut and palm)

Certain nuts (macadamia)

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Types of Fat (2)

Monounsaturated fats: found primarily in plant sources, are liquid at room temperature, and are semisolid or solid when refrigerated

Olive, safflower, peanut, and canola oils

Avocados

Many nuts

Polyunsaturated fats: commonly referred to as “oil”; liquid at room temperature and when refrigerated

Corn and soybean oils

Fish, including trout, salmon, and anchovies

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Cholesterol

Cholesterol: waxy substance that is needed for several important body functions

Body produces it from the liver and obtains it from animal food sources (meat, cheese, eggs, milk)

Too much cholesterol can clog arteries and lead to cardiovascular disease

LDLs (low-density lipoproteins) are the “bad” cholesterol, while HDLs (high-density lipoproteins) are considered “good”

Recommended: consume no more than 300 milligrams per day

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Trans Fats

Trans fatty acids: liquid vegetable oils that have been chemically changed through the process of hydrogenation to extend the shelf life of processed foods

Pose a risk to cardiovascular health by raising LDL levels and lowering HDL levels

Foods high in trans fatty acids:

Crackers, cookies, chips

Cakes and pies

Doughnuts

Deep-fried foods like french fries

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Omega-3 and Omega-6 Fatty Acids

Omega-3 fatty acids: contain alpha-linolenic acid, help slow the clotting of blood, decrease triglyceride levels, improve arterial health, and lower blood pressure

Fatty fish; vegetable oils; dark green leafy vegetables

Omega-6 fatty acids: contain linoleic acid and are also important to health, though Americans often consume too much in proportion to omega-3

Note there are concerns about fish consumption due to contamination with mercury and other pollutants

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Minerals—A Need for Balance

Minerals are naturally occurring substances needed by the body in small amounts

Build strong bones and teeth, and help carry out metabolic processes and body functions

The body needs 20 essential minerals

Macrominerals (need at least 100 milligrams per day)

Calcium, chloride, magnesium, phosphorous, potassium, sodium

Microminerals (need less than 100 milligrams per day)

Chromium, cobalt, copper, fluorine, iodine, iron, zinc, manganese, nickel, and others

A balanced diet provides all the essential minerals the body needs per day

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Vitamins—Small but Potent Nutrients

Vitamins are naturally occurring organic substances needed by the body in small amounts

Serve as catalysts for releasing energy from carbohydrates, proteins, and fats while maintaining other body components

Your body needs at least 11 specific vitamins

A, C, D, E, K, and the B-complex vitamins

Vitamins can be found in a variety of foods, so supplements are often unnecessary

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Table 5.2 Overview of RDIs

Water: 1–1.5 ml per calorie spent; 8–12 cups of fluid

Carbohydrates: AMDR: 45–65% of calories consumed

Added sugars: no more than 10–25% of calories consumed

Fiber: 14 g for every 1,000 calories consumed; 21–25 g for women, 30–38 g for men

Protein: AMDR: 10–35% of calories consumed; 0.36 g per pound of body weight

Fat: AMDR: 20–35% of calories consumed

Saturated fat: less than 10% of calories consumed

Trans fat: as little as possible

Minerals:

6 macrominerals: more than 100 mg

14 trace minerals: less than 100 mg

11 essential vitamins: varies

Source: Macronutrients table, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, by the Food and Nutrition Board, Institute of Medicine of the National Academies, 2002/2005, http://iom.nationalacademies.org/ Reports/2002/Dietary-Reference-Intakes-for-Energy-Carbohydrate- Fiber-Fat-Fatty-Acids-Cholesterol-Protein-and-Amino-Acids.aspx.

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Other Substances in Food: Phytochemicals

Phytochemicals: substances naturally produced by plants

May keep cells healthy, slow tissue degeneration, prevent carcinogens, reduce cholesterol, protect heart, maintain hormone levels, and keep bones strong

Three important types of phytochemicals:

Antioxidants: neutralize the effects of free radicals

Phytoestrogens: lower cholesterol and reduce risk of heart disease

Phytonutraceuticals: may inhibit growth of cancer and heart disease

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Figure 5.1 The color wheel of foods.

An optimal diet contains fruits and vegetables from all seven groups.

Jump to long image description

Source: Adapted from What Color Is Your Diet? by D. Heber, 2001, New York: HarperCollins, p. 17.

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Planning a Healthy Diet

When food is metabolized, it fuels our bodies

The energy provided by food is measured in kilocalories, commonly shortened to calories

One kilocalorie equals the amount of energy needed to raise the temperature of 1 kilogram of water by 1 degree centigrade

Fats provide 9 calories per gram

Carbohydrates and protein provide 4 calories per gram

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2015–2020 Dietary Guidelines for Americans

Five overarching concepts:

Follow a healthy eating pattern across the lifespan

Focus on variety, nutrient density, and amount

Limit calories from added sugars and saturated fats and reduce sodium intake

Shift to healthier food and beverage choices

Support healthy eating patterns for all

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2015–2020 Dietary Guidelines for Americans (2)

Three food patterns:

Healthy U.S.-style pattern based on typical American foods, but in nutrient-dense forms and appropriate amounts

Healthy Mediterranean-style pattern contains more fruits and seafood and less dairy; more than half the fat calories are from olive oil

Healthy vegetarian-style pattern includes more legumes (beans and peas), soy products, nuts and seeds, and whole grains; contains no meats, poultry, or seafood

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Basics of a Healthy Eating Pattern (Figure 5.2)

Combine healthy choices from these groups, based on an appropriate calorie level:

A variety of vegetables, including dark green and red and orange; legumes; starchy vegetables; and others

Fruits, especially whole

Grains, at least half of which should be whole grains

Fat-free or low-fat dairy

A variety of protein foods

Oils instead of solid fats; but not tropical oils

Limit these components:

Saturated fats and trans fats, to less than 10% of calories per day

Added sugars, to less than 10% of calories per day

Sodium, to less than 2,300mg per day

Alcohol, to no more than one drink for women and two drinks for men per day

Source: Dietary Guidelines for Americans: 2015–2020, by the U.S. Department of Agriculture, www.dietaryguidelines.gov.

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2015–2020 Dietary Guidelines for Americans (3)

Individual calorie requirements are calculated based on sex and age at three activity levels:

Sedentary: only light physical activity

Moderately active: equivalent to walking 1.5 miles per day at 3–4 mph

Active: more than 3 miles per day at 3–4 mph

Americans of all ages should strive to meet the Physical Activity Guidelines for Americans to promote health and reduce the risk of chronic disease

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Table 5.3 Estimated Calorie Requirements

Gender	Age	Sedentary	Moderately Active	Active
Female	14–18	1,800	2,000	2,400
Female	19–25	2,000	2,200	2,400
Female	26–50	1,800	2,000	2,200
Female	51+	1,600	1,800	2,000-2,200
Male	14–18	2,000–2,400	2,400–2,800	2,800–3,200
Male	19–35	2,400–2,600	2,600–2,800	3,000
Male	36–50	2,200–2,400	2,400–2,600	2,800
Male	51+	2,000–2,200	2,200–2,400	2,400–2,800

Source: Dietary Guidelines for Americans: 2015–2020, by the U.S. Department of Agriculture, www.dietaryguidelines.gov/.

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MyPlate

Visual icon that illustrates the five food groups as a reminder about maintaining a healthy diet

Emphasizes foods high in nutrient density: the proportion of nutrients to total calories in a food

Diet of nutrient-dense foods from each food group allows for a discretionary calorie allowance that can be consumed as added fats, sugars, alcohol, or other foods

At the 2,000-calorie level, 270 discretionary calories—about 2 cans of regular cola or 30 potato chips

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Figure 5.3 The USDA MyPlate.

Introduced in 2010, MyPlate promotes a dietary balance of five basic food groups: fruits, grains, vegetables, protein, and dairy. The MyPlate website, choosemyplate.gov, contains resources and interactive tools.

Source: “MyPlate, My Wins Tipsheet,” January 2016, U.S. Department of Agriculture, Center for Nutrition Policy and Promotion.

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The DASH Eating Plan

Dietary Approaches to Stop Hypertension

Developed by the National Heart, Lung, and Blood Institute

More emphasis on sodium reduction

Adds a nuts, seeds, and legumes group to the food groups in a healthy diet

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Limiting Red Meats

Research supports a link between red meat consumption and heart disease, cancer, and diabetes

Pork as well as beef, lamb, and veal

American Cancer Society recommends no more than 18 ounces (cooked) of red meats per week and avoiding or limiting processed meat

Processed meats are high in sodium and saturated fat

U.S. males aged 19–20 get more protein than they need and should consume more vegetables and other foods

Vegetarian Diets

These diets may offer protection against obesity, heart disease, high blood pressure, diabetes, digestive disorders, and some forms of cancer

Vegetarians need to make sure their diets provide the energy intake and food diversity necessary to meet dietary guidelines

The Nutrition Facts Label

Regulated by the FDA

Lists serving size and number of servings

Gives total calories per serving

Shows % Daily Value (DV): the percentage that a nutrient in a serving of food contributes to a daily diet

Shows the DV for key vitamins and minerals

Look for foods with no more than 30% of calories from fats and no more than 10% from added sugar

Figure 5.4 Nutrition Facts panel on a food label (left) and proposed changes (right).

The proposed new label has been redesigned to emphasize calories, serving size, and DV percentages. Key changes include information on added sugars, more realistic serving sizes, and calorie and nutrition information for the whole package for certain products, such as soft drinks. Calories from fat no longer appear; the total number of calories is emphasized instead. DVs of potassium and vitamin D are now included, but DVs of vitamins A and C are optional. The bottom panel better explains % DV.

Sources: “Proposed Changes to the Nutrition Facts Label,” last updated October 23, 2015, U.S. Food & Drug Administration, www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/LabelingNutrition/ucm385663.htm; “Proposed Nutrition Facts Label Changes Are Based on Science and Research,” last updated September 1, 2015, U.S. Food & Drug Administration, www.fda.gov/forconsumers/consumerupdates/ucm387164.htm.

Claims on Food and Dietary Supplement Packaging

Some food descriptors and health claims on food packaging are regulated by the FDA; others are not yet well regulated

Light can be used if the product has one-third fewer calories or half the fat of the regular product

Dietary supplements are less regulated than foods

Information can be misleading and confusing

Restaurant Menu Labels

2010 Affordable Care Act includes a requirement that all chain restaurants provide calorie counts on their menus

Studies show only a marginal change in calorie consumption

Researchers have also found symbols indicating healthy choices are more likely than numbers to be effective

Current Consumer Concerns

Overconsumption of soft drinks

Diet sodas are no better and may be worse for health

Nearly all contain high levels of caffeine

Soda drinkers consume less milk and fruit juices

Overconsumption of salt

May be a factor in causing hypertension; can damage the brain and hinder cognitive functions

Many packaged foods, convenience foods, and restaurant foods are heavily salted

Current Consumer Concerns (2)

Food allergies and food intolerances

Eight foods are responsible for 90% of food allergies: milk, eggs, peanuts, tree nuts, shellfish, soy, and wheat

Food intolerances such as lactose intolerance are less severe

Celiac disease and gluten

Celiac disease is an immune reaction to gluten, which is found in wheat, barley, rye, and triticale

Current Consumer Concerns (3)

Energy bars and energy drinks

Energy bars are more healthy than candy bars and other snack foods, but they an be high in calories and sugar

Energy drinks are not considered a health risk if consumed in recommended amounts, although there is some concern about acid that is damaging to tooth enamel

Mixing hard alcohol and energy drinks can result in greater intoxication than intended, can pose a danger to heart muscle fibers, and can cause extreme dehydration

Current Consumer Concerns (4)

Probiotics, prebiotics, and synbiotics

Probiotics are living bacteria that may aid digestion; prebiotics are nondigestible carbohydrates that fuel probiotics

Synbiotics combine the two

Scientific studies have not confirmed health benefits

Fast Foods

Fast-food meals are high in calories, fat, sodium and sugar and low in vitamins, minerals, and fiber

Don’t supersize

Go easy on toppings

Order grilled chicken or fish on whole wheat

Order dressing on the side or fat-free

Order vegetables instead of other choices

Have orange juice, low-fat, milk, or water instead of soda

For desert, order yogurt and fruit

A Fast-Food Meal (Figure 5.7)

Food	Calories	Total Fat (g)	Saturated Fat (g)	Sodium (mg)
Hamburger	670	39	11	1,020
Medium fries	360	18	5	640
Medium chocolate shake	690	20	12	560
Totals	1,720	77	28	2,220
Compare with RDIs for 3 meals	2,000	<65	<20	<1,500

Food Deserts

There are more fast-food restaurants in low-income neighborhoods than in affluent ones

Food deserts: low-income areas where more than 500 people or 33% of the population have low access to a supermarket or large grocery store

More than 1 mile from a store in urban areas and more than 10 miles in rural areas

Organic Foods

Plant foods grown without synthetic pesticides or fertilizers

Animal foods raised on organic feed without antibiotics or growth hormone

USDA regulates labeling

Research has not demonstrated health benefits, but environmental benefits are clear

Look for foods that are not only organic but also locally grown

Wash organic produce thoroughly

Foodborne Illnesses

Food intoxication: food poisoning in which food is contaminated by natural toxins

Botulism

Food infection: food poisoning in which food is contaminated by disease-causing microorganisms, or pathogens

Norovirus, E. coli, salmonella, campylobacter

Pet food can contain salmonella

Use safe food practices and store food safely, especially leftovers

Genetically Modified Foods

Genetically modified (GM) organisms: genetic makeup has been changed for desirable traits

Modern biotechnology is faster and more refined than selective breeding

Many crops are already GM

Sixty percent of processed foods in supermarkets contain one or more GM ingredients

Safety is assessed by the FDA’s Center for Food Safety and Applied Nutrition (CFSAN)

In Review

What kinds of nutritional guidelines are established by the federal government?

What are the categories of nutrients?

How do you plan a healthy diet?

What are the main nutrition-related concerns currently affecting our society?

What are the main food-safety issues?

Appendix A

Long image descriptions

Figure 5.1 The Color Wheel of Foods Appendix

The wheel consists of seven groups, delineated by their dominant colors

Red group: items such as pink grapefruit, watermelon, and tomatoes

Red/purple group: items such as cherries, grapes, and red wine

Orange group: items such as cantaloupe, carrots, and mangoes

Orange/yellow group: items such as oranges, orange juice, papaya, and peaches

Yellow/green group: items such as avocadoes, peas, and honeydew melon

Green group: items such as broccoli, cabbage, and other dark leafy greens

White/green group: items such as onions, celery, and white wine

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