Chapter 2 – Planning Healthy Diets
2.2 Nutrition and Health
What is Nutrition?
Simply put, foods are the plants and animals that we eat, and nutrition is how our bodies use these foods. 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 contains macronutrients including protein, carbohydrate, and fat that not only offer calories to fuel our bodies and give us energy, but also 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 our bodies operate optimally.” [1] Phytochemicals are substances in plants that provide smell, taste, and color. Notice the varied colors, shapes, and textures of the vegetables in the image below. They are not technically nutrients, but many have been shown to affect human health. Zoochemicals are similar substances naturally found in animal foods.
The study of nutrition goes beyond a discussion of food and the nutrients the body needs. It includes how those nutrients are digested, absorbed, and used by the body. It examines how food provides energy for daily activities and how our food intake and choices affect body weight and the risk of 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.
How Nutrition Affects Health
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 (Figure 2.3) , including heart disease, cancer, diabetes, and stroke. [5]
Nutrition can affect the health of the mind and 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 resulting from these dietary patterns may play a role in brain function 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. The term diet refers to the overall foods a person eats. One important facet of lifestyle is personal dietary habits, which 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 influence food choices and nutrition status. Following a healthy lifestyle improves your overall health and well-being.
VIDEO: “How the Food You Eat Affects Your Brain” by Mia Nacamulli TED ED (June 2016), 3:46 minutes.
Factors that Affect Food Choices
Both environmental factors and lifestyle habits influence the foods people choose to eat. Food itself plays an important role in regulating appetite and how the body feels after eating. Foods high in fiber and protein tend to increase feelings of fullness by slowing digestion and prolonging satiety. Choosing foods that maximize nutrient intake and satiety can help regulate how much is eaten and how long one feels satisfied between meals.
Food choices are also shaped by social, cultural, and religious influences. Food carries meaning beyond nutrition and often reflects traditions, values, and shared experiences. Special occasions—such as holidays, celebrations, and even funerals—are commonly marked by specific foods. Cultural background and upbringing influence what foods are considered familiar, acceptable, or comforting.
Recognizing these influences can help individuals make healthier food choices while still respecting cultural traditions and personal values. The video below illustrates how the use of chopsticks spread from Asian cultures and became widely accepted around the world, highlighting how food practices can cross cultural boundaries over time.
VIDEO: “Why 1.5 Billion People Eat with Chopsticks” by Jennifer 8 Lee (January 21, 2020) 3:26 minutes.
Other Factors that Affect Food Choices
Many factors influence what we eat beyond hunger and nutritional needs:
- Taste and appearance: Flavor, texture, and how food looks strongly affect choices and can change with repeated exposure.
- Cost and access: Income, location, and food availability can limit healthy options.
- Early experiences: Foods eaten in childhood often shape lifelong preferences.
- Habits: Daily routines can support or hinder healthy eating.
- Culture: Traditions influence what, when, and how we eat.
- Geography: Where you live affects access to foods like fresh produce or seafood.
- Media and advertising: Marketing can shape preferences and eating behaviors.
- Social influences: Family, friends, and social settings impact food choices.
- Health needs: Allergies, intolerances, and medical conditions may require diet changes.
- Emotions: Stress, mood, and comfort can influence eating.
- Sustainability: Some people consider environmental impact when choosing foods (e.g., local or plant-based options).
This combination of factors helps explain why food choices are complex and highly individual.
Discussion Starters
- How might the way we nourish our bodies affect the health of our planet?
- Debate your classmates: Should a nation’s government try to influence what foods people of the nation eat?
- Consider the top three foods you eat and explain why you eat these items most frequently.
Review Questions
Check your understanding of this section by answering these questions.
attributions
This section is an adaptation of “Nutrition and Health” in Nutrition: Science and Everyday Application, V. 1.0 by Alice Callahan, PhD; Heather Leonard, MEd, RDN; and Tamberly Powell, MS, RDN under a Creative Commons Attribution-NonCommercial 4.0 International License.
- Academy of Nutrition and Dietetics. (2019). How to Explain Basic Nutrition Concepts. Retrieved December 18, 2019, from https://www.eatrightpro.org/practice/practice-resources/international-nutrition-pilot-project/how-to-explain-basic-nutrition-concepts ↵
- Medline Plus. (2019). Definitions of Health Terms. Retrieved from https://medlineplus.gov/definitions/nutritiondefinitions.html ↵
- World Health Organization. (n.d.) Constitution. Retrieved from https://www.who.int/about/who-we-are/constitution ↵
- World Health Organization. (2018, February 22). Nutrition. Retrieved from https://www.who.int/news-room/facts-in-pictures/detail/nutrition ↵
- Ahmad FB, Cisewski JA, Anderson RN. Mortality in the United States: Provisional Data, 2024. Vital Statistics Rapid Release. 2025 Sep;(39):1–5. DOI: https://dx.doi.org/10.15620/cdc/174621. ↵
- Aubrey, A. & Chatterjee, R. (2019, October 19). Changing Your Diet Can Help Tamp Down Depression, Boost Mood. Retrieved from https://www.npr.org/sections/thesalt/2019/10/09/768665411/changing-your-diet-can-help-tamp-down-depression-boost-mood ↵
Plants and animals that we eat
The sum of all processes involved in how organisms obtain nutrients, metabolize them, and use them to support all of life’s processes.
The nutrients needed in relatively large amounts (between 50 and 150+ grams). They include carbohydrates, proteins, and fats.
Essential nutrients that are needed by the body in small amounts. These include vitamins and minerals.
Non-nutrient chemicals naturally found in plants that have health benefits. (Phyto refers to plants.)
Health promoting substances in animal foods that are believed to provide health benefits beyond the traditional nutrients that food contains.
A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity
The state of being in good health, especially as an actively pursued goal
The World Health Organization (WHO) is an agency of the United Nations responsible for international public health.
According to the WHO, "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity"
Lack of proper nutrition, caused by not having enough to eat or not eating enough of the right things.
The inherited characteristics of a person passed from genes received from parents.
The surroundings or conditions in which a person lives
The stages through which a person passes through during his or her lifetime.
The way in which a person or group lives.
The type foods that a person consumes.
A feeling of fullness
