What Is Nutrition?
Inherent to the definition of nutrition, food is the primary means by which most people nourish themselves. Our nutritional status depends mostly on the food (and beverages) we consume. Likewise, the types and quantity of food we choose to eat (or that is available to us) can depend, in part, on our nutritional status (e.g. consider how food choices might vary if a person is underweight vs. overweight). <br />
As with food, nutrients are inherent to the definition of nutrition. Nutrients are chemical substances in food, beverages, and supplements that are utilized throughout the body to provide structure and fuel metabolic processes. We are nutrients! The nutrients, and combinations of nutrients, that we consume directly affect our nutritional status, and our nutritional status can influence how we absorb and metabolize the nutrients we consume.
One word, many meanings! <br />• The noun “diet” refers to the overall types and quantities of foods and beverages people (or animals or communities) regularly consume. <br />• However, in common usage, the noun “diet” usually refers to a particular plan of food and beverage consumption that is adhered to for a specific purpose or goal, and often for a limited period of time (e.g., a weight-loss diet, an elimination-diet to identify food allergens, etc). <br />• The verb “diet” generally refers to restriction of one’s usual diet (types and/or quantities of foods) in order to lose weight. As with food, the diets people consume affect their nutritional status, and in turn, people’s nutritional status can affect their dietary choices.
Dietary supplements provide isolated nutrients and other food components in a non-“natural” form (e.g. pill or powder). Micronutrient supplements are the most common (vitamins and minerals), with doses ranging from those commonly found in foods to pharmacological (and potentially harmful) doses. As with food, the supplements people consume affect their nutritional status, and, in turn, people’s nutritional status can affect their decision to use supplements.
While many herbs are used in food preparation to enhance flavor, herbal supplements generally refer to products derived from plants, or parts of plants, that are consumed for the purpose of maintaining or improving health. Often sold in the form of teas, pills, or powders, these supplements are classified as “dietary” supplements, rather than as over-the-counter medications, because of the 1994 Dietary Supplement Health and Education Act (DSHEA). While they often contain limited quantities of nutrients, various herbals can affect appetite, absorption, and/or the metabolism of nutrients, and, in turn, nutritional status. As with other types of supplements, an individual’s nutritional status could also affect their decision to use an herbal supplement.
Heating food in various ways, for various lengths of time, and with other ingredients, can change its structure in ways that affect palatability, safety, and nutrient availability...and in turn, our nutritional status. Consider: <br />• Palatability: Raw carrots have a crunch many people prefer over soft, boiled carrots. But roasting can caramelize natural sugars in carrots and enhance flavor. <br />• Food safety: Heating food to specific temperatures can destroy pathogens and natural plant toxins that can cause illnesses and/or compromise nutrient absorption and/or metabolism.<br />• Nutrient availability: No easy generalities!<br /> - Some nutrients can be “lost” in cooking water, if they are not fully degraded by the heat of cooking first (e.g. vitamin C). <br /> - But cooking can actually increase the availability of other nutrients in foods by breaking down plant cell walls or other compounds (e.g. oxalic acid) that bind nutrients.<br /> - Nutrient content can also increase when cooking “shrinks” the bulky volume of some foods (e.g. 1 cup of cooked spinach has more vitamin C than 1 cup of raw spinach because many more spinach leaves fit into a cup when cooked vs raw). <br /> - Other ingredients used during cooking or food preparation can affect nutrient availability (e.g. cooking vegetables with an alkaline substance, like baking soda, can degrade some nutrients…although adding an acid, like tomatoes, can counteract that).<br />As with food and diet in general, a person’s nutritional status may influence their decisions about how to cook or otherwise prepare their food.Want to know more? The New York Times offers a helpful “user-friendly” summary. (Click on the blue hotspot!)
nyti.ms Tara Parker-Pope answers a reader’s question about the best way to prepare vegetables.
In common usage, the term “taste” actually refers to taste, smell, and texture. That said, if you like the “taste” of something, you’re more likely to eat more, and thus get more nutrients (or harmful compounds). But our taste can change with our nutritional status too (e.g. extreme malnutrition).
Physical activity burns energy/calories, but it also breaks down and rebuilds muscle and other tissues more than when we’re sedentary. So the more active we are, the more nutrients our bodies need to fuel our activity and maintain body structures. In turn, our nutritional status can affect our capacity for physical activity, ranging from basic activities of daily living in malnourished individuals to the performance of professional athletes.
Emerging research has associated the type, quantity, and even timing of food/nutrient intake with a variety of neuroendocrine and psychological processes that affect behavior and emotions. For example, irregular eating patterns can lead to drops in blood sugar that can result in irritability; and tryptophan (an amino acid), carbohydrates, and some B-vitamins are needed for the brain to make serotonin, which can influence mood. Other research has linked dietary components with risk of Alzheimer’s disease and depression. And while food can influence our mental health, our mental health can influence our food choices (e.g. over/under-eating when stressed, poor food choices due to mental illnesses such as schizophrenia, depression, and eating disorders, etc).
Our individual nutritional needs depend, in part, on our genetic make-up. For example, the fact that blood cholesterol levels can go up, down, or stay the same in response to a low-fat diet is due, at least in part, to genetic differences between individuals. But can our nutritional intake/status influence our genes? Actually, yes! What we eat can turn on or off certain genes in our bodies. Growing areas of research are nutrigenetics (how genetic variation influences the interaction between diet and disease) and nutrigenomics (how nutrients and other food components influence gene “expression” -- see also Epigenetics).
Factors in the external environment can turn on or off various genes in the body – and in some cases, we can pass those on/off changes to our offspring! Things like stress, smoking, physical activity, and, you guessed it, diet can turn on/off different genes. And since our bodies, including our epigenome, are comprised of broken down food components, it’s no surprise that research suggests our “epigenome” can influence our nutritional needs/status (e.g. propensity for overweight). Please check out the following video (blue hotspot) and interactive website (green hotspot) to learn more about the role of environmental factors (red hotspot), and nutrition (yellow hotspot) in particular, on our health!
Digestion starts in the mouth with the mechanical action of chewing, as well as with the enzymes in our saliva, so good oral health is essential for our ability to eat and obtain nutrients from our food. Good oral health can also help protect the body from infections, which, if chronic, can compromise nutritional status. In turn, dietary factors can influence oral health. For example, foods and beverages high in added sugars can contribute to dental carries. Nutritional factors also can influence cranio-facial development, oral cancers, and oral infectious diseases.
Our nutritional needs vary as we progress through infancy, childhood, adolescence, young adulthood, mid-life, and older adulthood. In women, pregnancy and lactation status also influence nutritional requirements. On the flip side, our nutritional status can play a role in how quickly we achieve growth milestones, including puberty. Nutritional status can also affect how we look and feel as we “age” (chronic malnutrition can stress body structures, including skin, and impair healing), as well as fertility.
Medicines can be useful and powerful tools in preventing and curing disease, but many also have side effects, which can affect taste, appetite, and nutrient absorption and metabolism. In turn, past and present nutritional status can influence our growth, development, and susceptibility to infectious and chronic disease; abnormalities or diseases that result from suboptimal nutrition may influence our need/use of medications or medical procedures and devices.
The high financial costs of eating healthfully have received much attention in both mainstream and academic media, especially in the US and other industrialized nations with a high prevalence of chronic diseases associated with suboptimal over-nutrition. While there is some confusion and controversy about exactly how much money is necessary to eat “healthfully,” it is clear that economics and dietary adequacy are related. This relationship is particularly apparent in many lower income and politically unstable communities. Suboptimal nutrition can contribute to fatigue, cognitive and physical difficulties, and myriad acute and chronic diseases; these, in turn, can affect school and job performance and income of individuals, families, communities, and even the economic health of an entire nation.
Optimal nutrition is key to preventing the onset, or limiting the severity, of numerous acute and chronic diseases. From vitamin A supplementation to obesity prevention programs, myriad prevention efforts across the globe aim to improve the nutritional status of their target populations. In turn, the nutritional status (and subsequent health status) of a population determines the need for – and type of – preventive interventions.
Strapped for time, with numerous competing interests and demands, convenience is a key factor in many people’s daily decisions about what, when, and how to eat. While the foods most people find convenient (at least in industrialized countries) frequently provide suboptimal nutrition, efforts to make healthy food more convenient have the potential to improve people’s nutritional status. In turn, people’s nutritional status may influence what foods they find convenient (e.g., fatigue or illness due to suboptimal nutrition may limit people’s ability to shop for and/or prepare foods).
Both formal and informal education can directly – and indirectly – influence nutrition. Direct knowledge about which foods (and in what quantities) provide the greatest “nutritional density” contributes to optimal nutritional status in individuals and population groups, as does knowledge about how best to store and prepare food. In turn, nutritional status can influence cognitive capacity and motivation to learn in the first place. Education also indirectly effects nutritional status by influencing income levels, values about and access to food and physical activity, and overall health.
Homes, buildings, markets, roads, open spaces, and other physical infrastructure – everything “built” by humans comprises our built environment. These structures influence access to food (stores, markets, restaurants, vending machines, roads to get food to and from these places, etc), as well as levels of physical activity and exposure to pollutants in air and water, all of which can influence nutritional status. The nutritional status of communities can influence decisions about how to create or modify the built environment as well (e.g., a community with a high prevalence of under-nutrition may benefit from new, paved roads between farms and urban areas).
Various naturally occurring and man-made toxins are ingested via contaminated food. These toxins include those produced by plants themselves (e.g. solanine in green potatoes); others may be absorbed from the environment and stored in the plant or animal (especially in fat-tissue in meat/fish/poultry). Cooking and other food preparation techniques can limit the effects of some naturally occurring toxins, such as those found in some mushrooms and pufferfish. Toxins can contaminate foods even after they have been “processed,” such as mold and BPA (bisphenol A, which is used in some food and beverage packaging, cups/bottles, and water supply pipes). Even essential nutrients can be toxic if consumed in high enough doses (nearly always in the form of dietary supplements). Toxins can compromise nutritional status through the diseases they cause. In turn, nutritional status may impact susceptibility to toxins and ability to recover post-exposure.
From anemia to xerophthalmia, numerous diseases can directly result from suboptimal nutrition. Diet also plays a part in the development and progression of some multi-factorial conditions such as cardiovascular disease. Likewise, some diseases can deplete the body’s nutrient stores, and/or lead to loss of appetite, malabsorption, and altered mental states, resulting in diminished nutritional status (e.g. celiac sprue and anorexia nervosa).
Food preferences, food preparation practices, and values and beliefs about what, when, where, why, and how to eat are often greatly influenced by culture…even who gets to eat specific foods and how much. And anything that affects food intake is likely to affect nutritional status. But does nutritional status affect culture? Sometimes, yes! If the prevalence of suboptimal nutrition is high, cultural customs may change to reflect efforts to improve the nutritional status of certain (or all) members of the cultural group.
Advertisements, branded toys, product placement in stores/TV/movies/textbooks, school incentive programs, sponsorships, etc. – marketing influences nearly everyone’s food choices to varying degrees…and their nutritional status. In turn, a population’s nutritional status may influence companies’ marketing strategies (e.g., educational materials at low-income pediatric health clinics developed with funding from a fortified food manufacturer).
People’s overall satisfaction with life depends on many things, including their physical, economic, social, emotional, and spiritual health and wellness. Nutrition affects overall well-being through its affects on all of these aspects. Likewise, people’s sense of well-being can influence their food choices and, in turn, their nutritional status.
The type, quality, quantity, and frequency of access to food affects nutritional status. Nutritional status can affect food access through its affects on physical and mental health, economics, and well-being. Governments and other organizations may also create programs to improve food access based on the nutritional status of a population.
Food pantries, free and reduced-price school meals, the supplemental nutrition assistance program (SNAP), and emergency aid during humanitarian crises all represent efforts to improve access to food in population groups suffering from, or at risk of, malnutrition. So nutritional status is, at least by design, a determining factor in the receipt of food aid. And food aid can directly influence nutritional status.
Institutional and government policies can have myriad effects on a population’s nutritional status. The courses of action outlined in agricultural, trade, educational, environmental, and health policies can play direct and/or indirect roles in who receives clean, safe, and nutritionally adequate food and water…and therefore, adequate nutritional intakes. In turn, the nutritional status of a population can shape the development and implementation of these policies.
The right to “a standard of living adequate for the health and well-being of himself and of his family, including food…” is part of the UN’s Universal Declaration of Human Rights (blue hotspot). Other human rights, however, may also impact nutritional status, including education, gender and racial equality, prohibition of human trafficking, etc. Could nutritional status of a population impact the scope of human rights afforded to its citizens? Absolutely. For example, populations with suboptimal nutritional status may have limited capacity for self-advocacy.
Politics shape policies, and in turn, the nutritional status of populations. Many things influence politics, but concerns about a constituency’s health and/or ability to contribute to the economy (which are influenced by nutritional status) can drive political arguments that shape agricultural, trade, educational, environmental, and health policies. Likewise, nutritional status may influence politics; for example, populations with poor nutritional status may have limited “political clout” within a government.
From field to market to table, clean water, clean hands, and clean facilities for food storage, processing, and preparation are essential to protect food and beverages from food spoilage and contamination with infectious agents or toxins that can cause disease and, in turn, compromise an individual’s nutritional status. Nutritional status could affect sanitation practices too, through its effects on mental and physical health and the resultant capacity to create and maintain sanitary conditions.
Healthy soil and water contains minerals and other nutrients that nourish plants and the animals that eat them (including humans). On the other hand, pollutants and toxins in the air, ground, and water can also be absorbed by plants and animals and passed up the food chain to people (and/or directly absorbed through contact with contaminated water and soil). Either way, the health of the environment can affect people’s nutritional status. Nutritional status could affect the environment as well, through its effects on mental and physical health and the resultant capacity to care for Earth’s resources.
Agricultural practices can have a profound impact on the nutrient content (and taste!) of food, and in turn, nutritional status. These practices include those that affect the nutrient content of soil, growth rate of plants and animals, time of harvest (before/at/after peak ripeness), breeding practices (e.g. based on size, yield, pest resistance, climate adaptability, resistance to bruising, and taste), biodiversity, and soil and water health, including waste disposal and use of pesticides and synthetic fertilizers. Often, the relationships between agriculture and nutrition involve both pro’s and con’s; for example, greater crop yields have the potential to provide adequate nutrition to more people, but sometimes at the cost of greater pesticide use and diminished taste. The nutritional status of a population can affect agriculture as well, by driving innovation to meet people’s nutritional needs and desires and/or by limiting innovation and production when agriculture workers are themselves malnourished and unable to work to their full capacity.
Clearly, the sun is necessary for all life on Earth, including the plants we eat (or feed to the animals we eat). But even more directly, the sun’s rays convert a compound in our skin cells (7-dehydrocholesterol) into vitamin D3, a precursor of the active form of vitamin D (1,25-dihydroxyvitamin D) in our bodies. On the flip side, our nutritional status clearly can’t influence the sun -- but it may influence our choices to go outside and soak up a few rays.
The relative amount of fat, muscle, bone, and water in our bodies -- and, in some cases, where they’re located (e.g., excess fat around the waist) -- determines our body composition. Since the human body is comprised of nutrients, our nutrient intake is essential to our body composition and our nutrient status can actually be measured, in part, by measuring our body composition. In turn, our body composition influences our nutritional needs.
While often overlooked as a nutrient, water is a key component of most of our beverages, fruits, vegetables…and us! At 50 – 70% of the human body, water serves as a solvent, lubricant, transport vehicle for other nutrients and waste, and medium for temperature regulation and other chemical processes. Water is essential for our nutritional status, and our nutritional status (e.g. dehydration) can drive our desire for water and water-rich foods.
Sleep: How much sleep we get can influence our body weight/body mass index (an indicator of body composition). While the exact mechanisms remain somewhat unclear, both observational and experimental research finds that lack of sleep increases calorie consumption, at least in some people in Western, obesogenic-environments. Nutritional status can also affect sleep quality and duration, ranging from increased risk of sleep apnea among obese adults to excessive and/or disrupted sleep patterns in malnourished infants and children.
While influenced by culture, values about food often vary among individuals of the same cultural group. Our values about food include the amount of time and money we invest in food purchasing, preparation, and consumption, particularly in relation to other goods and services. The priority we give to taste, convenience, and a wide range of environmental and social justice concerns can also impact our food choices, and in turn, our nutritional status. Our nutritional status can also influence our values about food; for example, environmental concerns may be less valued than easy access to cheap calories in communities suffering from a high prevalence of malnutrition.
The social, political, and environmental upheavals of war can have profound effects on a population’s health, including its access to food and, in turn, nutritional status. Can the nutritional status of its population affect a country’s decision to go to war, and/or how successfully they engage in war? Absolutely. In fact, the US passed federal school lunch legislation in 1946 partly out of concern about the number of military recruits turned away during World War II because of physical limitations due to malnutrition – including malnutrition the recruits experienced as children 10 -12 years earlier during the Great Depression. The US Department of Defense currently sponsors the Fresh Fruit and Vegetable Program for schools.
vimeo.com An introductory look at the relationship between DNA, genes and the Epigenome.
vimeo.com Why do the physical characteristics of identical twins diverge as they age? Follow the interaction of the environment and the genome in a pair of twins over time.
learn.genetics.utah.edu Nutrition & the Epigenome

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