Nutritional Epidemiology & Study Designs

Question 1

What is nutritional epidemiology?

Answer 1

The study of diet-disease relationships in populations using epidemiological methods.

Question 2

What is a challenge unique to nutritional epidemiology?

Answer 2

Diet is complex to measure and dietary factors are often interrelated.

Question 3

What do cross-sectional studies measure?

Answer 3

Exposure and outcome at a single point in time (“snapshot”).

Question 3

What are the main health outcomes studied in nutritional epidemiology?

Answer 3

Disease incidence,
mortality,
growth,
nutrition status.

Question 4

What are pros of cross-sectional studies?

Answer 4

Estimate prevalence,
quick,
cheap,
assess multiple exposures and outcomes.

Question 5

What are cons of cross-sectional studies?

Answer 5

Cannot determine causality,
prone to reverse causality,
unclear time order.

Question 6

What are pros of case-control studies?

Answer 6

Good for rare diseases,
quick,
explore many exposures.

Question 6

What are case-control studies?

Answer 6

Compare past exposures in people with a disease (cases) and without (controls).

Question 7

What are cons of case-control studies?

Answer 7

Prone to recall bias,
selecting controls is hard,
cannot calculate risk directly.

Question 8

What are pros of cohort studies?

Answer 8

Time order is clear,
can study multiple outcomes,
allows incidence and risk calculations.

Question 9

What are cohort studies?

Answer 9

Follow a group over time to track exposures (diet) and future outcomes (disease).

Question 10

What are cons of cohort studies?

Answer 10

Time-consuming,
costly,
dropout bias,
diet may change,
confounding risk.

Question 11

What is a famous example of a cohort study?

Answer 11

Nurses’ Health Study – linked trans-fat to heart disease.

Question 12

What are Randomized Controlled Trials (RCTs)?

Answer 12

Participants are randomly assigned to a diet intervention or control group.

Question 13

What are pros of RCTs?

Answer 13

Best for causality,

randomization controls confounding,

exposure is controlled.

Question 14

What are cons of RCTs?

Answer 14

Costly,

hard to do long-term or for whole diets,

adherence issues,

limited generalizability.

Question 15

What are ecological studies?

Answer 15

Examine group-level data (e.g. country sugar intake vs diabetes rates).

Question 16

What are pros of ecological studies?

Answer 16

Cheap,

fast,

good for generating hypotheses,

use existing data.

Question 17

What are cons of ecological studies?

Answer 17

Ecological fallacy,

no individual-level data,

confounding risk.

Question 18

What is an example of an ecological study in nutrition?

Answer 18

Countries with high fish intake have lower heart disease rates.

Question 19

What are meta-analyses and systematic reviews?

Answer 19

Studies that combine findings from many other studies to give overall conclusions.

Question 20

What are pros of meta-analyses?

Answer 20

More statistical power,

resolve inconsistencies,

high-level evidence.

Question 21

What are cons of meta-analyses?

Answer 21

Quality depends on the included studies,

subject to publication bias;

methods may vary.

Question 22

Why are observational studies important in nutrition?

Answer 22

Trials are often not feasible,

so well-designed cohorts or case-control studies provide evidence.

Question 23

How is causality best tested in nutrition?

Answer 23

RCTs, when feasible, provide strongest evidence for diet-outcome effects.

Question 24

What is a food frequency questionnaire (FFQ)?

Answer 24

A common tool in cohort studies to estimate long-term diet.

Question 25

What are issues with dietary assessment in nutrition research?

Answer 25

Measurement error, recall bias, under/over-reporting.

Question 26

What is the role of biomarkers in nutrition studies?

Answer 26

Help validate diet reports (e.g. vitamin D blood levels).

Question 27

Why is confounding a problem in nutrition studies?

Answer 27

Diet is linked to many behaviors (exercise, income), requiring adjustment.

Question 28

How is confounding addressed?

Answer 28

Using multivariate analysis, regression models, and sometimes nutrient density approaches.

Question 29

What is an example of using study designs to assess SSBs and diabetes?

Answer 29

Cohort: SSBs and future diabetes; RCT: remove SSBs and test insulin response; Meta-analysis: pooled risk estimates.

Question 30

Why are multiple study designs used in nutrition?

Answer 30

Different designs provide complementary evidence for building policy and understanding causality.

Question 31

What is the ecological fallacy?

Answer 31

Assuming group-level associations apply to individuals (which may not be true).

Question 32

Why can't some hypotheses be tested in RCTs?

Answer 32

It's unethical or impractical to randomly assign harmful diets or restrict key nutrients long-term.

Question 33

What is the evidence hierarchy in nutritional epidemiology?

Answer 33

Meta-analyses > RCTs > cohort studies > case-control > cross-sectional > ecological.

Question 34

What’s the importance of systematic reviews in nutrition policy?

Answer 34

They synthesize total evidence for guidelines and public health decisions.

Question 35

How is nutrition epidemiology used in practice?

Answer 35

Informs policies like saturated fat limits and fruit/veg intake targets based on long-term studies.

Question 36

Why is understanding study design important in nutrition?

Answer 36

It allows critical evaluation of evidence quality and validity of conclusions.