REVISION STM3233 LECTURE 3 (HMY)

In a cohort study investigating the long-term effects of dietary fiber on heart health, which of the following best describes the primary advantage of this type of epidemiological study?

• It allows for the establishment of causality between dietary fiber intake and heart health.

• It can track changes in dietary habits and health outcomes over time.

• It provides immediate results regarding the effects of dietary fiber.

• It can control all variables that might affect heart health.

Answer explanation

Cohort studies excel in observing how variables (like dietary fiber intake) and outcomes (like heart health) change over a long period.

What is a key limitation of cross-sectional studies in nutritional epidemiology?

• They only measure dietary intake at a single point in time.

• They require a very large sample size.

• They are typically more expensive than cohort studies.

• They always require invasive data collection methods.

Answer explanation

Cross-sectional studies provide a snapshot of data at one point in time, limiting the ability to assess causality or changes over time.

In a case-control study examining the relationship between vitamin D deficiency and the risk of developing osteoporosis, what is the primary method of selecting participants?

• Participants are selected based on their vitamin D levels and then monitored for the development of osteoporosis.

• Participants with osteoporosis (cases) are compared to those without (controls) to examine past vitamin D levels.

• Participants are selected from a general population without considering their disease status or vitamin D levels.

• All participants are given a vitamin D supplement and then observed for changes in bone density.

Answer explanation

In case-control studies, cases (people with the condition) are compared to controls (people without the condition) to look for previous exposure (like vitamin D deficiency).

What is a key characteristic of a prospective study in nutrition research?

• It starts after a health outcome has occurred and looks back at potential risk factors.

• It collects data from participants over time before health outcomes have occurred.

• It relies solely on historical data and records for data collection.

• It typically involves a small number of participants for in-depth analysis.

Answer explanation

Prospective studies follow participants over time and collect data before any outcomes, like the development of a disease, have occurred.

In a retrospective nutritional epidemiology study examining the link between early-life diet and adult obesity, what is the primary method of data collection?

• Real-time tracking of dietary intake and body weight from early life to adulthood.

• Randomized assignment of dietary interventions to observe future outcomes.

• Analysis of existing records and historical dietary information of adults with obesity.

• Long-term observation of individuals without any pre-determined hypothesis.

Answer explanation

Retrospective studies often rely on existing records or historical data to analyze past exposures or behaviors in relation to current health outcomes.

Which statement best describes a limitation of retrospective studies compared to prospective studies in nutrition research?

• Retrospective studies cannot use statistical methods to analyze data.

• They are more expensive and time-consuming than prospective studies.

• Retrospective studies may be more prone to recall bias and inaccuracy in data.

• They cannot study rare diseases or outcomes.

Answer explanation

Since retrospective studies often rely on participants’ memory or historical records, they are more susceptible to recall bias and inaccuracies.

In a nutrition study, a strong positive correlation is found between the consumption of high-sugar beverages and the incidence of type 2 diabetes. What does this correlation imply?

• High-sugar beverage consumption causes type 2 diabetes.

• There is a relationship between sugar intake from beverages and type 2 diabetes, but causality cannot be inferred.

• The consumption of high-sugar beverages is the only factor leading to type 2 diabetes.

• There is no relationship between high-sugar beverages and type 2 diabetes.

Answer explanation

A correlation indicates a relationship but does not establish a cause-and-effect relationship.

An epidemiological study finds that populations with a higher intake of fruits and vegetables have lower rates of heart disease. However, these populations also have higher physical activity levels. What is a critical consideration for interpreting these results?

• Fruit and vegetable intake is unrelated to heart disease.

• Physical activity, not diet, is the primary factor in reducing heart disease.

• The study results might be influenced by confounding variables, like physical activity.

• The study conclusively proves that fruits and vegetables prevent heart disease.

Answer explanation

The presence of other factors, like physical activity, that could influence the outcome, indicates a potential confounding variable.

If an epidemiological study in nutrition research reports a "relative risk" of 2.0 for developing obesity when consuming a certain diet, what does this mean?

• The diet doubles the risk of developing obesity compared to not following the diet.

• The diet reduces the risk of developing obesity by half.

• There is a 2% risk of developing obesity when consuming this diet.

• The diet guarantees the development of obesity.

Answer explanation

A relative risk of 2.0 indicates that the risk is twice as high in the group following the diet compared to a control group.