1.1 Defining Nutrition, Health, and Disease

Americans are bombarded with television programs that show where to find the best dinners, pizzas, and cakes, and the restaurants that serve the biggest and juiciest burgers. Other programs feature chefs battling to prepare meals, and the top places to burst your belly from consuming atomic chicken wings and deli sandwiches longer than a foot. There are also shows that feature foods from cultures around the world. How do you use the information from popular network food shows to build a nutritious meal? You don’t—these shows are for entertainment. The construction of a nutritious meal requires learning about which dietary patterns are healthy, how nutrients function in your body, and how to use scientific resources. This text is designed to provide you with the information necessary to make sound nutritional choices that will optimize health and help prevent disease.

The word nutrition first appeared in 1551 and comes from the Latin word nutrire, meaning “to nourish.” Today, we define nutritionThe sum of all processes involved in how organisms obtain nutrients, metabolize them, and use them to support all of life’s processes. as the sum of all processes involved in how organisms obtain nutrients, metabolize them, and use them to support all of life’s processes. Nutritional scienceThe investigation of how an organism is nourished, and how nourishment affects personal health, population health, and planetary health. is the investigation of how an organism is nourished, and incorporates the study of how nourishment affects personal health, population health, and planetary health. Nutritional science covers a wide spectrum of disciplines, ranging from cell to society. As a result, nutritional scientists can specialize in particular aspects of nutrition, such as biology, physiology, immunology, biochemistry, education, psychology, sustainability, and sociology.

Without adequate nutrition the human body does not function optimally, and severe nutritional inadequacy can lead to disease and even death. The typical American diet is lacking in many ways, from not containing the proper amounts of essential nutrients, to being too speedily consumed, to being only meagerly satisfying. Dietitians are nutrition professionals who use their knowledge of nutritional science to help people achieve a healthy diet and develop good dietary habits. The Academy of Nutrition and Dietetics (AND) is the largest organization of nutrition professionals worldwide, and registered dietitian nutritionists (RDNs) are committed to helping Americans eat well and live healthier lives. To learn more from AND’s nutritional advice visit the Academy of Nutrition and Dietetics website. The equivalent organization in Canada is called the Dietitians of Canada, where the registered professionals are called registered dietitians (RDs). To learn more, visit the Dietitians of Canada website.

Your ability to wake up, to think clearly, to communicate, to hope, to dream, to go to school, to gain knowledge, to go to work, to earn a living, and to do all of the things that you like to do is dependent upon one factor—your health. Good health means you are able to function normally and work hard to achieve your goals in life. For the next few minutes, take some time to view snapshots of the insides of the refrigerators of American mechanics, doctors, school teachers, hunters, short-order cooks, college students, vegans, and more. Visit Mark Menjivar’s portrait exhibition, “You Are What You Eat” (refer to “Interactive: Refrigerator Portraits”). Menjivar hopes these images will invoke new thoughts about “[h]ow we care for our bodies. How we care for others. And how we care for the land.” As you look at these images, think about your personal health, the health of your family and friends, and the health of this planet. These hopes encompass the inspirations for this book.

In 1946, the World Health Organization (WHO) defined healthA state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.” This definition was adopted into the WHO constitution in 1948 and has not been amended since. DiseaseAny abnormal condition that affects the health of an organism and is characterized by specific signs and symptoms. is defined as any abnormal condition affecting the health of an organism, and is characterized by specific signs and symptoms. Signs refer to externally identifiable characteristics of a disease, such as swelling, weight loss, or fever. Symptoms are the features of a disease recognized by a person experiencing them, such as nausea, fatigue, irritability, and pain. Diseases are broadly categorized as resulting from pathogens (i.e., bacteria, viruses, fungi, and parasites), deficiencies, genetics, or physiological dysfunction. Diseases that primarily affect physical health are those that impair body structure (as is the case with osteoporosis) or functioning (as is the case with cardiovascular disease). Mental illnesses primarily affect mental and social well-being. Some mental illnesses are classified as diseases.

The foods we eat affect all three aspects of our health. For example, a teen with type 2 diabetes (a disease brought on by poor diet) is first diagnosed by physical signs and symptoms, such as increased urination, thirstiness, and unexplained weight loss. But research has also found that teens with type 2 diabetes may have impaired thinking and do not interact well with others in school, thereby affecting mental and social well-being. Type 2 diabetes is just one example of a physiological disease that affects all aspects of health—physical, mental, and social.