Nutrition - week 2

placebo

"Fake" treatment given to control group in the same manner as actual treatment

Steps of the Scientific Method

1. Making an observation 2. Proposing a hypothesis 3. Experimentation

Hypotheses can predict?

1.) Cause-and-effect relationships (causal relationships) • Example: One factor, such as excess energy intake, causes another factor, such as weight gain 2.) Correlations (associations) • Example: Television watching is associated with weight gain in children

A well-conducted experiment requires?

1.) Quantifiable Data -Can we measure the information in a scientific manner? 2.) Appropriate Experimental Population -Is the population large enough and pertinent to the study? 3.) Proper Controls -Can we ensure that the population ate or drank what we said they did?

example of scientific method

1.) observation : children in orphanages suffered from pellagra, but the staff didn't 2.) hypothesis: pellagra is due to a deficiency of something in the diet 3.) experiments: experimental design - nutrition foods were added to orphan children. results - those with healthy diet recovered from pellagra. experimental design - 11 volunteers ate a diet lacking the dietary substance. results - 6 of the 11 got pellagra. continued experiments - studies with both humans and animals. 4.) theory: pellagra is caused by deficiency in B vitamin niacin

epidemiological studies

A study that involves large-scale comparisons amoung groups of people, ussually contrasting a group known to have been exposed to some toxicant and a group that has not. ex: Cross-sectional studies, Case-control studies, Cohort studies

Cautious interpretations and conclusions

Accumulation of evidence

Intervention Study

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

Double-Blind Study

Experiment where neither participants nor scientists know to which group the participants have been assigned

Single-Blind Study

Experiment where participants do not know which treatment they are receiving

National Health and Nutrition Examination Survey (NHANES)

Federally funded epidemiologic study begun in 1970s to assess trends in diet and heath in the 1970s to assess trends in diet and heath in the US population • National Center for Health Statistics (NCHS)

control group

Group of people, animals, or cells in an intervention study that does not receive the experimental treatment. Determines whether effects seen in the treatment group are caused by treatment or by something else

complex relationship

Involves one or more interactions

Findings are preliminary when published

Not meaningful by themselves. Findings need to be replicated

Positive correlation

Not necessarily a desired outcome

Hawthorne effect

Phenomenon in which study results are influenced by alteration of something that is not related to the actual study intervention

placebo effect

Phenomenon showing an apparent effect of the treatment because the individual expects or believes that it will work

disadvantages of animal studies

Question whether applicable to humans

Simple relationships

Relationship between two factors, not influenced or modified by another factor

Peer review

Research has validity

Disadvantages of Epidemiologic Studies

Results cannot be interpreted as proving a causal relationship • Subject may not be representative of an entire population

Data Collection (scientific methods)

Scientists must: 1.) Design an appropriate study • Depends on the type of hypothesis 2.) Carefully conduct the study Interpret the data correctly

Scientific Method

Series of steps scientists use to test theories

In vitro systems

Study of cells or environments that are not part of a living organism

In vivo systems

Study of natural phenomena in a living organism

Advantages of Epidemiologic Studies

Used to explore complex interactions that exist among genetic, environmental, and lifestyle factors • Example: Framingham Heart Study

Random assignment

When study participants have equal chance of assignment to each experimental group. • Minimizes Hawthorne effect placebo effect and. Minimizes Hawthorne effect, placebo effect, and research bias. Distributes confounding variables (factors that might influence outcome of an experiment) equally among study groups

interactions

When the relationship between two factors is influenced or modified by another factor

researcher bias

When the researcher influences results of a study

Tolerable Upper Intake Levels (ULs) are ________. a.) the maximum daily intake level not likely to cause harmful effects b.) based on intakes from only supplements and highly fortified foods c.) nutrient intake goals d.) set for all nutrients

a

Human Intervention Study

a study of a population in which there is an experimental manipulation of some members of the population; observations and measurements are made to determine the effects of this manipulation

The nutrient standards used on Nutrition Facts panels are called ________. a.) Recommended Dietary Allowances b.) Daily Values c.) Estimated Average Requirements d.) Dietary Reference Intakes

b

To be defined as a "good" source of calcium, a food must contain ________. a.) at least 5% of the Daily Value for calcium in 1 serving of the food b.) at least 10% of the Daily Value for calcium in 1 serving of the food c.) at least 50% of the Daily Value for calcium in 1 serving of the food d.) at least 50% of the Daily Value for calcium in 2 servings of the food

b

Which claims are NOT closely regulated by the Food and Drug Administration (FDA)? a.) Health claims b.) Structure/function claims c.) Nutrient content claims d.) All of these

b

Which is NOT a permitted health claim? a.) Diets with enough calcium may reduce risk of osteoporosis. b.) Diets low in sugar may reduce the risk of cancer. c.) Diets low in saturated fat and cholesterol may reduce the risk of cardiovascular disease. d.) None of these responses are permitted.

b

For a health claim to be made about a food product, it must NOT contain more than ________. a.) 19 g fat b.) 70% carbohydrate c.) 4 g saturated fat d.) 120 mg cholesterol e.) All of these choices are correct

c

Foods that provide a greater contribution to nutrient needs than calorie needs are said to be ________. a.) empty calorie b.) energy dense c.) calorie dense d.) nutrient dense

d

The MyPlate vegetable group is divided into which subgroups? a.) Starchy vegetables, red & orange vegetables, and dark green vegetables b.) Dark green vegetables and other vegetables c.) Other vegetables, starchy vegetables, and red & yellow vegetables d.) Dark green vegetables, red & orange vegetables, starchy vegetables, beans and peas, and other vegetables

d

Which counts as one cup of fruit? a.) Large banana b.) Small apple c.) Medium pear d.) All of these

d

The Dietary Guidelines for Americans are designed to reduce the risk of ________. a.) cancer b.) cardiovascular disease c.) obesity d.) foodborne illness e.) All of these responses are correct

e

negative correlation

no correlation

Activity levels interact with energy intake in children to influence?

obesity risk

Correlations

only prove association

Fat intake and genetics interact to influence?

risk of influence risk of heart disease

experimental studies

studies in which the independent variables are directly manipulated and the effects on the dependent variable are examined. ex: Laboratory-based animal studies, Laboratory-base in vitro studies, Clinical trials

hypothesis (scientific method)

• A prediction about the relationship between variables • Explains why the event occurred example: "The increase in childhood obesity is due to lack of exercise" or "The increase in childhood obesity is caused by consuming too much fat"

advantages of animal studies

• Genetic variability is less than humans • Can control all aspects of animal's environment • Foundation for future human trials

Framingham Heart Study

• Large-scale epidemiologic study • Initiated in 1940 due to rise in heart disease • Identified associations with serum cholesterol • Identified associations with serum cholesterol and smoking and risk for heart disease • Public health efforts now address relationship between lifestyle factors and risk of heart disease

interacting factors

• Lifestyle Factors: Diet, Exercise • Environmental Factors: Exposure to pollutants • Genetic Factors

Observation (scientific method)

• Serves as framework for the rest of the scientific method • Must be valid • If observation is flawed, resulting conclusion will likely be flawed • All available facts and data must be considered to determine if an observation is correct example: "childhood obesity rates have dramatically increased

Cell culture systems

• Specific types of cells that can be grown in the lab and used for research • Example: Breast cell cultures grown to study disease