1.1: Defining Nutrition, Health, and Disease

Learning Objectives

• Explain the terms nutrition, health, health promotion, and disease prevention.
• Describe factors that influence food choices.

We are bombarded with images and messages about food everywhere we go. We see super models eating giant burgers, chefs battling to prepare meals, and influencers telling us how to follow the latest diet on various social media platforms. How do you use the information from entertainers and influencers to build a nutritious meal? Hopefully...you don’t...at least, not before knowing whether they have the background to be a nutrition expert.

The construction of a nutritious meal requires learning about which foods are healthy and which foods are not-so-healthy, how foods and nutrients function in your body, and how to use scientific resources to make healthful choices for you and those you care about. This text is designed to provide you with the information necessary to make sound nutritional choices that will optimize health and help prevent disease.

Nutrition, Health and Disease

Nutrition science is the investigation of how an organism is nourished, and includes the study of how nourishment affects personal health, population health, and planetary health. Nutrition science includes a wide spectrum of disciplines 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. Nutrition is a relatively new discipline of science. Early research in nutrition focused on nutrient deficiencies. More recently, research has focused on supporting health and wellness, preventing and treating chronic diseases, and nutrigenomics (the interactions between genes, the environment, and nutrition).

Dietitians are nutrition professionals who integrate their knowledge of nutrition science into helping people achieve a healthy diet and develop good dietary habits. The Academy of Nutrition and Dietetics is the largest organization of nutrition professionals worldwide and dietitians registered with the Academy are committed to helping Americans eat well and live healthier lives. To learn more about dietitians, other nutrition professionals and the reliable nutrition advice they provide, visit www.eatright.org.

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 are dependent upon one factor—your health. Good health means you are able to function normally and work hard to achieve your goals in life. The World Health Organization (WHO) defines health as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.”

Disease is defined as any abnormal condition affecting the health of an organism, and is characterized by specific signs and symptoms. Signs are objective findings that can be seen or measured; some examples of signs include swelling, weight loss, or fever. Symptoms are subjective features of a disease recognized by a patient and/or their doctor. Symptoms can include nausea, fatigue, irritability, and pain. Diseases are broadly categorized as resulting from pathogens (i.e., bacteria, viruses, fungi, and parasites), nutrient deficiencies, genetics, and 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).

The foods we eat affect all three aspects of our health (physical, mental, and social well-being). For example, a teen with Type 2 diabetes (a disease often 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 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.

Public Health and Disease Prevention

In 1894, the first congressional funds were appropriated to the US Department of Agriculture (USDA) for the study of the relationship between nutrition and human health. Dr. Wilbur Olin Atwater was appointed as the Chief of Nutrition Investigations and is regarded as the “Father of Nutrition Science” in America. Under his guidance, the USDA released the first bulletin to the American public that contained information on the amounts of fat, carbohydrates, proteins, and energy (calories) in various foods. Nutritional science advanced considerably in these early years, but it took until 1980 for the USDA and the US Department of Health and Human Services (HHS) to jointly release the first edition of Nutrition and Your Health: Dietary Guidelines for Americans.

Although wide distribution of the Dietary Guidelines for Americans did not come about until the 1980s, many historical events that demonstrated the importance of diet to health preceded their release. Assessments of the American diet in the 1930s led President Franklin D. Roosevelt to declare in his inaugural address on January 20, 1937, “I see one-third of our nation is ill-housed, ill-clad, and ill-nourished.” From the time of Atwater until the onset of the Great Depression, nutrition scientists had discovered many of the vitamins and minerals that are essential for the functioning of the human body. Their work and the acknowledgement by President Roosevelt of the nutritional inadequacy of the American diet evoked a united response between scientists and government, leading to the enrichment (adding vitamins and minerals) of white flour, the development of free or reduced-cost school lunch programs, and advancements of nutrition education in this country.

In the latter part of the twentieth century nutrition scientists, public health organizations, and the American public increasingly recognized that eating too much of certain foods is linked to chronic diseases. We now know that diet-related conditions and diseases include hypertension (high blood pressure), obesity, Type 2 diabetes, cardiovascular disease, some cancers, and osteoporosis. These diet-related conditions and diseases are some of the biggest killers of Americans. For example, research indicates that unhealthy diets accounted for 529,299 deaths in 2016, with 84% of those deaths due to cardiovascular diseases.¹ The Dietary Guidelines for Americans², which are published every 5 years, aim to promote health and prevent chronic diseases. These guidelines outline ways to improve your overall eating patterns; you'll read more about these guidelines in Chapter 2.

Factors that Influence Food Choices

Knowledge of nutrition and dietary guidelines may influence the food choices you make, but there are a number of other factors that affect the dietary choices individuals make, including:

• Hunger vs. appetite. Hunger is the biological urge to eat; appetite is the psychological desire to eat specific foods.
• Sensory data. Cues that stimulate our five senses (sight, taste, hearing, touch, smell) can influence foods we choose.
• Taste, texture, and appearance. Individuals have a wide range of tastes which influence their food choices, leading some to dislike milk and others to hate raw vegetables. Some foods that are healthy, such as tofu, may be unappealing at first to many people. However, creative cooks can adapt healthy foods to meet most peoples’ taste.
• Economics. Access to fresh fruits and vegetables may be difficult, particularly for those who live in economically disadvantaged or remote areas, where cheaper food options are limited to convenience stores and fast food.
• Early food experiences. People who were not exposed to different foods as children, or who were forced to swallow every last bite of overcooked vegetables, may make limited food choices as adults.
• Habits. It’s common to establish eating routines, which can work for or against optimal health. Habitually grabbing a fast food sandwich for breakfast can seem convenient, but might not offer substantial nutrition. On the other hand, creating a healthy habit of drinking plenty of water each day can yield multiple benefits.
• Culture. The culture in which one grows up affects how one sees food in daily life and on special occasions.
• Religion. Various religious customs can influence foods eaten or avoided. For example, people of Jewish and Muslim faiths do not consume pork.
• Geography. Where a person lives influences food choices. For example, people who live in Midwestern US states have less access to fresh seafood than those living along the coasts.
• Advertising. The media greatly influences food choice by persuading consumers to eat certain foods.
• Social factors. Any school lunchroom observer can testify to the impact of peer pressure on eating habits, and this influence lasts through adulthood. People make food choices based on how they see others and want others to see them. For example, individuals can purchase cheap and fast pizzas or opt for high-end versions at fancy restaurants.
• Learning. Learning about new food, cultures, ways of eating, and even manufacturing practices can influence the foods we choose to eat and avoid.
• Health concerns. Some people have significant food allergies, to lactose or peanuts for example, and need to avoid those foods. Others may have developed health issues, which require them to follow a low-salt diet. In addition, people who have never worried about their weight have a very different approach to eating than those who have long struggled with excess pounds.
• Emotions. There is a wide range in how emotional issues affect eating habits. When faced with a great deal of stress, some people tend to overeat, while others find it hard to eat at all.
• Environmental concerns. Some people make food choices based on their environmental impact which may include opting for a vegetarian diet or purchasing local and/or organic food products.

Key Takeaways

• Nutrition science is the investigation of how an organism is nourished, and includes how nourishment affects personal health, population health, and planetary health.
• Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.
• Disease is defined as any abnormal condition that affects the health of an organism, and is characterized by specific signs and symptoms.
• Diet-related conditions and diseases include obesity, Type 2 diabetes, cardiovascular disease, some cancers, and osteoporosis.
• Good nutrition provides a mechanism to promote health and prevent disease.
• The Dietary Guidelines for Americans aim to promote health and prevent disease by outlining ways to improve your overall eating patterns.
• Numerous factors other than nutrition influence food choices.

References

1. The US Burden of Disease Collaborators. The State of US Health, 1990-2016: Burden of Diseases, Injuries, and Risk Factors Among US States. JAMA. 2018;319(14):1444–1472. doi:10.1001/jama.2018.0158. https://jamanetwork.com/journals/jama/fullarticle/2678018. Accessed March 31, 2020.

2. U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015 – 2020 Dietary Guidelines for Americans. 8th Edition. December 2015. https://health.gov/our-work/food-and-nutrition/2015-2020-dietary-guidelines/. Accessed March 31, 2020.