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1.2: Nutrition and Health

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  • Learning Objectives

    • Explain the terms nutrition, health, health promotion, and disease prevention.


    Simply put, food is the plants and animals that we eat, and nutrition is how food affects the health of the body. According to the Academy of Nutrition and Dietetics, “Food is essential—it provides vital nutrients for survival, and helps the body function and stay healthy. Food is comprised of macronutrients including protein, carbohydrate and fat that not only offer calories to fuel the body and give it energy but play specific roles in maintaining health. Food also supplies micronutrients (vitamins and minerals) and phytochemicals that don’t provide calories but serve a variety of critical functions to ensure the body operates optimally.”(Phytochemicals are compounds found in plants that give them their smell, taste, and color. They are not technically nutrients, but many have been shown to affect human health.)

    fruits and veggies
    Figure \(\PageIndex{1}\): Photo by Dan Gold / Unsplash License

    The study of nutrition goes beyond just a discussion of food and the nutrients needed by the body. It includes how those nutrients are digested, absorbed, and used by the cells of the body. It examines how food provides energy for daily activities and how our food intake and choices impact body weight and risk for chronic diseases such as heart disease and type 2 diabetes. It also provides insight on behavioral, social, and environmental factors that influence what, how, when, and why we eat.2 Thus, nutrition is an important part of the overall discussion of health and wellness.



    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.”3 The WHO recognizes nutrition as a critical part of health and development, noting that better nutrition is related to:4

    • improved infant, child and maternal health
    • stronger immune systems
    • safer pregnancy and childbirth
    • lower risk of non-communicable diseases (such as type 2 diabetes and cardiovascular disease)
    • greater longevity
    • greater productivity, creating opportunities to break cycles of poverty and hunger

    Malnutrition, including both undernutrition and overnutrition, is a significant threat to human health. In fact, nutrition is associated with four of the top ten leading causes of death in the United States, including heart disease, cancer, stroke, and diabetes.5

    Bar graph showing the 10 leading causes of death in the United States in 2020, in descending order:  heart disease, cancer, COVID-19, unintentional injuries. stroke, chronic lower respiratory diseases, Alzheimer disease, diabetes, influenza and pneumonia, and kidney disease.

    *COVID-19 became an official cause of death in 2020; rates for 2019 are not applicable.
    1Statistically significant increase in age-adjusted death rate from 2019 to 2020 (p < 0.05).
    2Statistically significant decrease in age-adjusted death rate from 2019 to 2020 (p < 0.05).
    NOTES: A total of 3,383,729 resident deaths were registered in the United States in 2020. The 10 leading causes of death accounted for 74.1% of all deaths in the United States in 2020. Causes of death are ranked according to number of deaths. Rankings for 2019 data are not shown.
    SOURCE: National Center for Health Statistics, National Vital Statistics System, Mortality.

    Figure \(\PageIndex{2}\): Age-adjusted death rates for the 10 leading causes of death: United States, 2019 and 2020. Mortality in the United States, 2020” by Centers for Disease Control and Prevention / Public Domain

    Nutrition can affect the health of the mind as well as the body. For example, some research suggests that the foods people eat can influence their mood. A 2019 study of moderately-depressed people aged 17 to 35 years old found that when half of them shifted towards a Mediterranean-style eating pattern for 3 weeks—emphasizing more fruits and vegetables, whole grains, lean protein sources, unsweetened dairy, fish, nuts and seeds, olive oil, and spices—their depression levels decreased compared to participants who continued their usual eating habits. Some (but not all) other studies have also found links between healthier diets and decreased risk of depression. It’s not clear why this might be, but researchers speculate that decreased inflammation or changes in the body’s microbiome caused by these dietary patterns may play a role in brain functioning and mental health.6 This is an area that requires much more research, but as you’re thinking about dietary choices, it’s worth thinking about how foods make you feel.

    In addition to nutrition, health is affected by genetics, the environment, life cycle, and lifestyle. One important facet of lifestyle is personal dietary habits. Dietary habits include what a person eats, how much a person eats during a meal, how frequently meals are consumed, and how often a person eats out. Other aspects of lifestyle include physical activity level, recreational drug use, and sleeping patterns, all of which play a role in health and impact food choices and nutrition status. Following a healthy lifestyle improves your overall health and well-being.

    Two young black women smiling and hugging, while enjoying themselves on the beach.
    Figure \(\PageIndex{3}\): Photo by Thought Catalog / Unsplash License


    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 of flour (adding vitamins and minerals), 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. The Dietary Guidelines for Americans7, which are published every 5 years, aim to promote health and prevent chronic diseases. These guidelines outline ways to improve your overall eating patterns.



    Nutrition: Science and Everyday Application by Alice Callahan, PhD, Heather Leonard, MEd, RDN, and Tamberly Powell, MS, RDN is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.  Available at:

    Introduction to Nutrition by Ann Diker.  Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0.  Available at: