Chapter 1: The Science of Nutrition

nutritional scientists

(scientists who study nutrition) can be found in many disciplines including, immunology, medicine, genetics, biology, physiology, biochemistry, education, psychology, sociology, as well as nutrition

Scientific method

1: making an observation 2: proposing a hypothesis 3: testing the hypothesis

Hawthorne effect

A change in a subject's behavior caused simply by the awareness of being studied

National Center for Health Statistics (NCHS)

A component of the U.S. Public Health Service whose mission is to compile statistical information to be used in improving the health of Americans

What percent of each macronutrient should make up your energy intake?

It is currently recommended that: 45 to 65% of your energy come from carbs 10 to 35% from proteins 20 to 35 from lipids

Minerals: provide structure and assist with regulation

Minerals (such as iron, selenium, and sodium) are inorganic substances that occur naturally in the earth. At least 16 minerals are essential nutrients, each serving its own specific purpose. Ex: Calcium is abundant in dairy products and provides the matrix for various structural components in your body (bone). Other minerals such as sodium you add to foods when you salt them, help regulate a variety of body processes (water balance). Selenium, which is abundant in many seeds and nuts, facilitate chemical reactions.

Graying of America

The phenomenon occurring in the United States in which the proportion of elderly individuals in the population is increasing with time.

Placebo

a "fake" treatment, given to the control group, that cannot be distinguished from the actual treatment.

PubMed

a computerized database that allows access to approximately 11 million biomedical journal citations

Autoimmune disease

a condition in which the immune system attacks an otherwise healthy part of the body

Disease

a condition that causes physiological or psychological discomfort, dysfunction or distress

Infectious disease

a contagious illness caused by a pathogen such as a bacteria, virus, or parasite

Confounding variable

a factor, other than the one of interest, that might influence to outcome of an experiment

National Health and Nutrition Examination Survey (NHANES)

a federally funded epidemiologic study begun in the 1970s to assess trends in diet and health in the U.S. population

Control group

a group of people, animals, or cells in an intervention study that does not receive the experimental treatment

Framingham Heart Study (1948)

a large epidemiologic study begun in the 1940s designed to assess the relationship between lifestyle factors and risk for heart disease

Risk factor

a lifestyle, environmental, or genetic factor related to a person's chances of developing a disease

Rate

a measure of the occurrence of a certain type of event within a specific period of time

Chronic degenerative disease

a noninfectious disease that develops slowly and persists over time

Life expectancy

a statistical prediction of the average number of years of life remaining to a person at a specific age

Proteins: make up muscles and are important for energy and regulation

abundant in many foods, including meat, legumes (such as dried peas), and some cereal products. Although most proteins consist primarily of carbon, oxygen, nitrogen, and hydrogen atoms, some also contain sulfur or selenium atoms. Source of energy, proteins also comprise the major structural material in various parts of the body including muscle, bone, and skin. Proteins allow us to move, support our complex internal communication systems, keep us healthy by their roles in the immune system (which protects against infection and disease), and regulate many of the chemical reactions needed for life.

Intervention study

an experiment in which something is altered or changed to determine its effect on something else

Noninfectious disease

an illness that is not contagious

Bomb calorimeter

an instrument that measures the heat energy released when foods are burned, thus providing an estimate of the potential energy of the foods

Kilocalories

because 1 calorie represents a very small amount of energy, the energy content of foods is typically expressed in units of 1,000 calories or kilocalories. Also known as kcalories or kcal and sometimes referred to as a Calorie as on food labels 1 Calorie is equivalent to 1,000 calories or 1 kcalorie

Lifestyle factors

behavioral component of our lives that we may or may not have control over (diet and exercise)

6 Nutrient categories based on their chemical structure and composition

carbohydrates, proteins, lipids, water, minerals, and vitamins

Carbohydrates: are vital for energy and regulatory roles

carbs consist of carbon, hydrogen, and oxygen atoms and serve a variety of functions in the body. There are many different types of carbohydrates; for example, those found in starchy foods like rice and pasta are quite different from those found in fruits and sweet desserts. Perhaps the most important carb is glucose. Most cells use glucose as their primary source of energy. Some carbs are used to make the genetic material (DNA) in cells. Other carbs such as dietary fiber play roles in maintaining the health of your digestive system and may help decrease your risk of certain conditions, including heart disease and type 2 diabetes. Carbs are also important structural and regulatory components of the membranes that surround the millions of cells in your body.

How many calories are in macronutrients?

carbs provide 4 kcalories/gram proteins provide 4 kcalories/gram lipids provide 9 kcalories/gram *alcohol provides 7 kcalories/gram

Adenosine Triphosphate (ATP)

compound used by cells to store and release energy Ex: The energy in ATP allows your muscles to move, drives nutrient digestion, and keeps you warm. Carbs, proteins, and lipids are called energy-yielding nutrients because their energy can be used to generate ATP.

Zoonutrients: Beneficial Substances from ANIMAL foods

compounds present in animal foods that provide health benefits beyond the provision of traditional nutrients and energy. Ex: Include a variety of nonessential lipids, found in fish and dairy products, that are thought to decrease your risk for heart disease

Energy

defined as the capacity of a physical system to do work. If something "has energy" it can cause something else to happen. Carbs, protein, and lipids all contain chemical energy. The body uses energy in foods to grow, develop, move, and fuel the many chemical reactions required for life.

Inorganic compounds

do not contain carbon-carbon or carbon-hydrogen bonds. Water and minerals are inorganic.

Environmental factors

element or variable in our surroundings which we may or may not have control over (exposure to pollutants)

Centers for Disease Control and Prevention (CDC)

federal government agency responsible for improving the overall health and safety of the people of the United States

Functional foods

foods that promote optimal health, above and beyond simply helping the body meet its basic nutritional needs. Functional foods contain (1) enhanced amounts of traditional nutrients, (2) phytochemicals, and/or (3) zoonutrients. Ex: Soy milk is considered a functional food because it contains phytochemicals thought to decrease risk for some cancers. Other examples are conventional cow's milk, which has been shown to be rich in zoonutrients that may lower your risks of cancer and high blood pressure. Although consuming functional foods may improve your health, the mechanisms by which this occurs are often poorly understood.

Phytochemicals: Beneficial substances from PLANT foods

found in plants that may help reduce the risk for developing certain diseases. Ex: Consuming phytochemicals found in tomatoes and garlic may decrease your risk of cancer. Grapes and wine contain phytochemicals that may reduce the risk of heart disease.

Vitamins: regulate reactions and promote growth and development

have a variety of chemical reactions and are abundant in most naturally occurring foods—especially fruits, vegetables, and grains Although they all contain carbon, oxygen, and hydrogen atoms, some vitamins also contain substances such as phosphorus and sulfur atoms. Your body needs vitamins to regulate its hundreds of chemical reactions as well as promote growth and development. Some vitamins called ANTIOXIDANTS, also protect your body from the damaging effects of toxic compounds such as those found in air pollution. Unlike carbs, proteins, and lipids, vitamins are not directly for structure or energy. However, they play important roles in the chemical processes required for building and maintaining tissue as well as in using the energy contained in the macronutrients. Vitamins can be classified based on how they interact with water, as either soluble (VITAMIN C and the B VITAMINS) or fat soluble (VITAMINS A, D, E, and K).

Lipids: are more than abundant energy sources

include a variety of oils and fats found in foods and the body, generally consist of carbon, oxygen, and hydrogen atoms. They provide large amounts of energy, are important for the structure of cell membranes, and are needed for your nervous and reproductive systems to function properly. Lipids also regulate a variety of cellular processes. Types of lipids found found in plant-based products such as corn oil and nuts are typically quite different from those found in animal-based foods such as meat, fish, eggs, and milk.

Genetic factors

inherited element in our lives that cannot be altered (inherited differences that influence physiology)

in vivo

involving the study of natural phenomena in a living organism

in vitro

involving the use of cells or environments that are not part of a living organism

Organic compounds

molecules that contain carbon atoms bonded to hydrogen atoms or other carbon atoms Carbohydrates, proteins, lipids, and vitamins are chemically organic nutrients.

Essential nutrients

must be obtained from your diet, because your body needs them and either can't make them at all or can't make them in adequate amounts

Mortality rate

number of deaths in a given period of time

Morbidity rate

number of illnesses in a given period of time

Infant mortality rate

number of infant deaths (<1 year of age) per 1,000 live births in a given year

Macronutrients versus Micronutrients

nutrients can also be classified on the basis of how much of them we require from our diet. Water, carbs, proteins, and lipids are called MACRONUTRIENTS, because they are needed in large quantities (over a gram each day). Vitamins and minerals are called MICRONUTRIENTS, because we need only very small amounts of them (often micrograms or milligrams each day). Ex: A typical adult requires about 2,726 pounds (1239 kg) of the MACRONUTRIENT protein over the course of a lifetime but only about 0.3 pounds (0.14 kg) of the MICRONUTRIENT iron

dietitians (RD- registerd dietitian)

nutrition professionals who help people make dietary changes and food choices to support a healthy lifestyle

Placebo effect

phenomenon in which there is an apparent effect of the treatment because the individual expects or believes that it will work

Peer-reviewed journal

published writings that have been analyzed by experts in the field

Simple relationship

relationship between two variables that cannot be altered by other factors Ex: Consuming inadequate iron for a long period of time results in iron-deficiency anemia

Complex relationship

relationship that involves one or more interaction

nutrition

science of how living organisms obtain and use food to support all the processes required for their existence

(Causative Hypothesis) cause-and-effect relationship

situation in which a change in one factor causes a change in another factor Ex: factor A (such as excess energy intake) causes factor B (such as weight gain).

Cell culture system

specific type of cells that can be grown in the laboratory and used for research purposes

Epidemiologic studies

study in which data are collected from a group of individuals who are not asked to change their behaviors in any way cannot prove causal relationships—they can only assess associations

double-blind study

study in which neither the experimenter nor the subjects know if the subjects are in the experimental or control group

single-blind study

study in which the subjects do not know if they are in the experimental or the control group

nutrients

substances in foods required or used by the body for at least one of the following: supplying energy, providing structure, or regulation of chemical reactions (metabolism) Ex: carbs supply energy to fuel your body's activities, calcium and phosphorus are important building blocks of your teeth and bones, and many of the vitamins are essential for chemical reactions such as those needed to protect your cells from the damaging effects of excessive sunlight and pollution

Etiology

the cause of origin of a disease

Primary (information) source

the location in which a scientific finding is first published

Incidence

the number of people who are newly diagnosed with a condition in a given period of time

Nutrition transition

the shift form undernutrition to overnutrition or unbalanced nutrition that often occurs simultaneously with the industrialization of a society

Prevalence

the total number of people who have a condition in a given period of time

Calories

the units used to measure how much energy is in food the more calories a food has, the more ATP the body can make from it

Animal study

the use of experimental animals such as mice, rats, or primates in a study

Negative correlation (also known as inverse correlation)

the variables change in opposite directions— as one increases the other decreases

Positive correlation

the variables change in the same direction—as one increases the other increases; one decreases the other decreases

conditionally essential nutrients

there are situations when a normally nonessential nutrient can become essential Ex: older children and adults must obtain two essential lipids through the diet, whereas babies are thought to require at least four, which they are unable to make. The additional lipids are therefore "conditionally essential" during early life. Certain diseases also cause normally nonessential nutrients to become conditionally essential.

Water: is the essence of life itself

water is made of oxygen and hydrogen atoms and makes up approximately 60% of your total body weight. The functions of water are varied and vital, including transport of nutrients, gases, and waste products; serving as a medium in which chemical reactions occur; and involvement in many chemical reactions. Water is also important in regulating body temperature and protecting your internal organs from damage.

Certified organic

when food has this label, it has been grown and processed according to the U.S. Department of Agriculture (USDA) national organic standards Ex: A farmer cannot use conventional pesticides and herbicides on organically grown crops. 100% Organic Cereal: Must have 95-100% certified organic ingredients Organic Cereal: Must have at least 70% certified organic ingredients Cereal made with organic grains: Organic ingredients can be listed on side panel Cereal: No organic claim is being made

Random Assignment

when study participants have equal chance of being assigned to each experimental group

Interaction

when the relationship between two factors is influenced or modified by another factor Ex: It is generally true that fat consumption is related to risk for heart disease This is a complex relationship because the association between excessive fat intake and heart disease can be altered or modified by other factors such as exercise and overall caloric intake.

Researcher bias

when the researcher influences the results of a study

(Correlative Hypothesis) correlation

when two or more events occur simultaneously, but one does not necessarily cause the other to happen

Non-essential nutrients

your body can make in amounts needed to satisfy its physiological requirements. Hence, you do not actually need to consume nonessential nutrients. Most foods contain a mixture of essential and nonessential nutrients. Ex: Milk contains a variety of essential vitamins and minerals (such as vitamin A and calcium) as well as nonessential nutrients (such as cholesterol).