Basic Nutrition, Third Edition

Basic Nutrition, Third Edition

Copyright © 2019 by Infobase

All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For more information, contact:

Chelsea House

An imprint of Infobase

132 West 31st Street

New York NY 10001

ISBN 978-1-4381-4380-4

You can find Chelsea House on the World Wide Web

at http://www.infobase.com

Contents

Introduction

Chapters

What Is Nutrition?

Carbohydrates

Dietary Fiber

Lipids

Protein

Water

Vitamins

Minerals

Choosing a Healthy Diet

MyPlate: Overview

MyPlate: Dairy

MyPlate: Fruits

MyPlate: Grains

MyPlate: Protein

MyPlate: Vegetables

Support Materials

Glossary

Further Resources

Bibliography

About the Author

Index

Introduction

A hundred years ago, people received nutritional guidance from mothers and grandmothers: Eat your carrots because they're good for your eyes; don't eat too many potatoes because they'll make you fat; be sure to get plenty of roughage so you can more easily move your bowels. Today, everyone seems to offer more advice: Add kale to your smoothie, only choose organic vegetables and grass fed beef, and avoid GMOs. Nutrition is one of those topics about which everyone seems to think they know something, or at least have an opinion. Whether it is the clerk in your local health food store recommending that you buy supplements or the woman behind you in line at the grocery store raving about her keto diet, everyone is ready to offer you nutritional advice. How do you know what to believe or, more importantly, what to do?

The purpose of these books is to help you answer these questions. Even if you don't love learning about science, at the very least you probably enjoy certain foods and want to stay healthy—or become healthier. In response to this, these books are designed to make the science you need to understand as palatable as the foods you love. Once you understand the basics, you can apply this simple health knowledge to your everyday decisions about nutrition and health. The Healthy Eating set includes one book with all of the basic nutrition information you need to choose a healthy diet, as well as five others that cover topics of special concern to many: weight management, exercise, disease prevention, food safety, and eating disorders.

Our goal is not to tell you to stop eating potato chips and candy bars, give up fast food, or always eat your vegetables. Instead, it is to provide you with the information you need to make healthy choices. You’ll come to understand that potato chips and candy are not poison, but they should be occasional treats, not everyday choices. We hope you will decide for yourself that fast food is something you can indulge in every now and then. And while you recognize that you should eat your vegetables, not everyone always does, so you should do your best to try new vegetables and fruits and eat them as often as possible.

These books take the science of nutrition out of the classroom and allow you to apply this information to the choices you make about foods, exercise, dietary supplements, and other lifestyle decisions that are important to your health. This knowledge should help you choose a healthy diet while allowing you to enjoy the diversity of flavors, textures, and tastes that food provides, and also encouraging you to explore the meanings food holds in our society. When you eat a healthy diet, you will feel good in the short term and enjoy health benefits in the long term. We can't personally evaluate each meal you consume, but we believe these books will give you the tools to make your own nutritious choices.

Lori A. Smolin,

Mary B. Grosvenor

David W. Ambrose

Chapters

What Is Nutrition?

Nutrition is the study of all of the interactions that occur between people and the food they eat.

It involves understanding which nutrients the human body needs, what kind of foods contain them, how the human body uses them, and the impact they have on human health. Nutrition also involves sociological, cultural, economic, and technological factors and the role they play in obtaining and choosing the foods we eat.

We Get Nutrients from Food

Nutrients are chemical substances in foods that provide energy, structure, and regulation of body processes Humans don't eat individual nutrients; they eat food. Food provides the body with energy and nutrients like vitamins and minerals; food also contains other substances, such as chemicals found in plants, called phytochemicals. Although they have not been defined as nutrients, they do have health-promoting properties.

When we make the right food choices, we get all of the calories, nutrients and other substances like phytochemicals that we need to stay healthy. But if we make too many poor food choices, we may be getting too little of some and too much of others. For example a diet low in dairy products is likely to be low in calcium and eventually lead to weakened bones. And a diet high in fats and sweets I likely to be high in calories and lead to unhealthy weight gain.

There are more than 40 nutrients that are essential to human life. We need to consume these essential nutrients in our diets because our bodies either cannot make them or they cannot make them in large enough amounts for optimal health. Food provides nutrients in different combinations and amounts. For example, beef, chicken, and fish provide protein, vitamin B6, and iron; bread, rice, and pastas provide carbohydrates, folic acid, and niacin; fruits and vegetables provide carbohydrates, fiber, vitamin A, and vitamin C; and vegetable oils provide fat and vitamin E. In addition to the nutrients that they naturally contain, many nutrients added to food by fortification to replace losses that occur during cooking and processing or to supplement the diet. Dietary supplements are also a source of nutrients. Although most people can meet their nutrient needs without them, supplements can be useful for maintaining health and preventing deficiencies.

Choosing a diet that provides enough of all the essential nutrients without excesses of calories or nutrients can be a challenge because we eat for many reasons other than to obtain nutrients. We eat because we enjoy the sight or smell of certain foods, it's lunchtime, we're at a party, we're in a sad or a happy mood, it's a holiday, and a multitude of other reasons. In order to meet nutrient needs, we must understand what these needs are and how to choose a diet that provides them.

Water is an essential nutrient that helps transport other nutrients, regulate body temperature, and provide structure for various body parts.

Source: Robert Kneschke. Shutterstock.

What Do Nutrients Do?

Nutrients provide three basic functions for the body: some nutrients provide energy, some provide structure, and some help to regulate the processes that keep us alive. Each nutrient performs one or more of these functions, and all nutrients together are needed for growth, for maintenance and repair, and for reproduction.

Energy

Certain nutrients provide the body with the energy or fuel it needs to stay alive, to move, and to grow. This energy keeps the heart pumping, the lungs respiring, and the body warm. It is also used to keep the stomach churning and the muscles working. Carbohydrates, lipids, and proteins are the only nutrients that provide energy to the body; they are referred to as the energy-yielding nutrients. The energy used by the body is measured in calories or kilocalories (abbreviated as kcalories or kcals). In some other countries, food energy is measured in joules or kilojoules (abbreviated as kjoules or kJs).

Each gram of carbohydrate provides the body with 4 calories. A gram of protein also provides 4 calories; a gram of fat provides 9 calories, more than twice the calories of carbohydrates or protein. For this reason, foods that are high in fat are high in calories. Alcohol can also provide energy in the diet, 7 calories per gram, but alcohol is not considered a nutrient because the body does not need it for survival.

The more calories a person uses, the more calories need to be supplied in the diet to maintain weight. Increasing exercise without increasing the amount of food eaten will lead to weight loss. Increasing food intake without increasing exercise will cause the extra energy to be stored, mostly as fat, resulting in weight gain. When a person consumes the same number of calories as he or she uses, body weight remains the same—this means the person is in energy balance.

Structure

There is truth to the saying you are what you eat because all of the structures in our bodies are formed from the nutrients we consume in our diet. By weight, our bodies are about 60% water, 16% protein, 16% fat, and 6% minerals. Water is a structural nutrient because it plumps up the cells, giving them their shape. Protein forms the structure of tendons, ligaments, and muscles and lipids are the major component of body fat; muscle and fat give the body its shape. The minerals calcium and phosphorus harden the bones, which provide the structural frame of the body and determine one's height and the length of the arms and legs.

Regulation

Nutrients are also important regulators of body functions. All of the processes that occur in our bodies, from the breakdown of carbohydrates and fat to provide energy, to the building of bone and muscle to form body structures, must be regulated for the body to function normally. For instance, the chemical reactions that maintain body temperature at 98.6°F (37°C) must be regulated or body temperature will rise above or fall below the healthy range. This constant internal body environment is called homeostasis. Maintaining homeostasis requires many different nutrients. Carbohydrates help to label proteins that must be removed from the blood. Water helps to regulate body temperature. Lipids and proteins are needed to make regulatory molecules called hormones, and certain protein molecules, vitamins, and minerals help to regulate the rate of chemical reactions within the body.

Nutrition Note: Is a Calorie a Kilocalorie?

There are 16 calories in a teaspoon of sugar. Yet, if in your chemistry class you measured the amount of energy in a teaspoon of sugar, the result would be about 16,000 calories, or 16 kilocalories. This is because the calories we use in nutrition to refer to the energy content of food are really kilocalories. A kilocalorie is 1,000 calories. Sometimes, as is the case on food labels, calorie is spelled with a capital C to indicate that it is referring to kilocalories. In the popular press, however, the term calorie with a lower case c is typically used to express the kilocalorie content of a food or of a diet. Therefore, when you eat a cookie that has 50 calories, keep in mind that it really has 50 kilocalories, or 50,000 calories.

Getting Nutrients to Your Cells

To get nutrients to the cells that need them, food must be digested and its nutrients must be absorbed. Digestion breaks food into small molecules and absorption brings these substances into the body, where they are transported to the cells.

The digestive system is responsible for the digestion and absorption of food. The main part of this system is the gastrointestinal tract, also called the GI tract. The GI tract is a hollow tube that starts at the mouth. From there food passes down the esophagus into the stomach and then on into the small intestine. Rhythmic contractions of the smooth muscles lining the GI tract help mix the food and propel it along. Substances, such as mucus and enzymes, are secreted into the GI tract to help with the movement and digestion of food. The digestive system also secretes hormones into the blood that help regulate GI activity. Most of the digestion and absorption of nutrients occurs in the small intestine. Once absorbed, nutrients are transported in the blood to the cells. Any material that has not been absorbed passes into the large intestine. Here, water and small amounts of some nutrients can be absorbed and the remaining wastes are excreted in the feces.

How the Body Uses Nutrients

Once they are inside body cells, carbohydrates, lipids, and proteins are involved in chemical reactions; the sum of these chemical reactions that occur inside body cells is called metabolism. The chemical reactions of metabolism synthesize the molecules needed to form body structures such as muscles, nerves, and bones. The reactions of metabolism also break down carbohydrates, lipids, and proteins to yield energy in the form of adenosine triphosphate (ATP). ATP is a molecule that is used by cells as an energy source to do work such as pumping blood, contracting muscles, or synthesizing new body tissue.

Nutrition Note: Too Much of a Good Thing Can Kill You

We usually think of the vitamins and minerals in our supplements as a healthy addition to our diets, but taking too much of one or more vitamin or mineral can be dangerous. Large doses of vitamins and minerals from dietary supplements can cause problems including nerve damage, kidney stones, liver and heart damage, and in extreme cases, death. For example, high doses of vitamin B6 can cause tingling, numbness, and muscle weakness; high doses of niacin can cause flushing; and too much vitamin C can cause diarrhea. Overdosing on iron from children's vitamin/mineral supplements is one of the leading causes of poisoning in children under the age of six. To be safe, take supplements according to the recommended doses and use the ULs from the DRIs to check for toxic doses.

The digestive system consists of the gastrointestinal tract (mouth, esophagus, stomach, small intestine, and large intestine) and accessory organs that secrete substances that aid digestion and absorption (salivary glands, liver, and pancreas). Beginning with the first bite, the digestive system starts the process of breaking down foods into units that are small enough to be absorbed into the body.

Source: Infobase.

The Six Classes of Nutrients

The nutrients we need come from six different classes: carbohydrates, lipids, proteins, water, vitamins, and minerals. Each of these classes, with the exception of water, includes a variety of different molecules that are used by the body in different ways. Carbohydrates, lipids, proteins, and water are often referred to as macronutrients because the body requires them in relatively large amounts. Vitamins and minerals are referred to as micronutrients because the body only needs them in small amounts.

Carbohydrates

Carbohydrates include sugars, starches, and fiber. Sugars are the simplest form of carbohydrate. They are made up of one or two sugar units. They taste sweet and are found in fruit, milk, and sweeteners like honey and table sugar. Starches are made of many sugar units that are linked together. They do not taste sweet, and are found in cereals, grains, and starchy vegetables like potatoes. Starches and sugars are good sources of energy in the diet and provide 4 calories per gram. Most fiber is also carbohydrate. Good sources of fiber include whole grains, legumes (peas and beans), fruits, and vegetables. Fiber provides little energy to the body because it cannot be digested or absorbed. It is, however, important for the health of the gastrointestinal tract.

Lipids

Lipids are commonly called fats. Fats are a concentrated source of energy in our diet and in our bodies, providing 9 calories per gram of fat. Most of the fat in our diet and in our bodies is in the form of triglycerides. Each triglyceride contains three fatty acids. Fatty acids are made up of chains of carbon atoms of varying lengths. Depending on how these carbons are linked together, fats are classified as either saturated or unsaturated. Saturated fats are usually solid at room temperature and are found mostly in animal products such as meat, milk, and butter. Unsaturated fats are found in vegetable oils and are usually liquid at room temperature. Small amounts of certain unsaturated fatty acids are essential in the diet. Cholesterol is another type of lipid found in animal foods. Diets high in saturated fat raise cholesterol levels in the blood and may increase the risk of heart disease. A type of unsaturated fat that is called trans fat should also be limited in the diet because it promotes heart disease.

Protein

Protein is needed for growth, maintenance and repair of body structures, and for the synthesis of regulatory molecules. It can also be broken down to provide energy (4 calories per gram of protein). Protein is made of folded chains of units called amino acids. The number and order of amino acids in the chain determine the type of protein. The right amounts and types of amino acids must be consumed in the diet in order to be able to build the proteins that the body needs. Animal foods such as meat, poultry, fish, eggs, and dairy products generally supply a combination of amino acids that meets human needs better than plant proteins do. However, vegan diets that contain only plant foods such as grains, nuts, seeds, vegetables, and legumes, can also meet our protein needs.

Water

Water is an essential nutrient that makes up about 60% of the weight of an adult human body. It provides no energy, but it is needed in the body to transport