Superfoods Research & Evidence-Based Practice 4 ā Questions and Answers
Question 1: The GRADE system used to evaluate superfood research evidence ranks 'RCT evidence' as high quality by default, but can downgrade it for which reason?
- Risk of bias, inconsistency, indirectness, imprecision, or publication bias (Correct answer)
- Failure to use animal models first
- Not including participants over age 70
- Use of industry funding alone
Correct answer: Risk of bias, inconsistency, indirectness, imprecision, or publication bias
GRADE (Grading of Recommendations Assessment, Development and Evaluation) downgrades RCT evidence based on methodological flaws, inconsistent results, surrogate endpoints, small samples, or selective reporting.
Question 2: A study reports that daily matcha tea consumption improved working memory in a 12-week trial. To evaluate generalizability, the most important question to ask is:
- What was the study population, and how does it resemble target consumers? (Correct answer)
- How much matcha was commercially available at the time?
- Was the study published in a high-impact journal?
- Did participants also consume other green teas?
Correct answer: What was the study population, and how does it resemble target consumers?
Generalizability (external validity) depends on whether the study sample (age, health status, baseline diet) resembles the population to whom findings will be applied.
Question 3: Which statistical measure best indicates the practical significance (not just statistical significance) of a superfood intervention?
- Effect size (e.g., Cohen's d or Hedges' g) (Correct answer)
- P-value below 0.05
- Sample size
- Confidence interval width alone
Correct answer: Effect size (e.g., Cohen's d or Hedges' g)
Effect size quantifies the magnitude of a difference or relationship, whereas a p-value only indicates whether an effect is unlikely due to chance regardless of its real-world importance.
Question 4: Polyphenol research frequently uses 'urinary metabolite excretion' as an outcome. What does this measurement assess?
- The amount of polyphenols absorbed and metabolized by the body (Correct answer)
- Kidney toxicity from high polyphenol doses
- Total polyphenol content of the food consumed
- Gut microbiome diversity after polyphenol intake
Correct answer: The amount of polyphenols absorbed and metabolized by the body
Urinary excretion of polyphenol metabolites (e.g., hippuric acid, quercetin conjugates) reflects systemic absorption and metabolism, serving as a biomarker of actual exposure.
Question 5: A systematic review on spirulina finds only 6 eligible RCTs, all with fewer than 50 participants. The review's primary limitation is:
- Insufficient statistical power to detect modest but real effects (Correct answer)
- Spirulina being too new to study scientifically
- Systematic reviews requiring at least 20 RCTs
- Small studies always containing fabricated data
Correct answer: Insufficient statistical power to detect modest but real effects
Small trials are underpowered, meaning they may fail to detect true effects or produce unstable estimates, limiting the conclusions a systematic review can draw.
Question 6: When a supplement company funds a clinical trial of its own turmeric product, this introduces which primary concern?
- Conflict of interest that may bias study design, analysis, or reporting toward favorable results (Correct answer)
- Legal barriers to publication in scientific journals
- Automatic exclusion from systematic reviews
- Requirement for FDA oversight of the trial
Correct answer: Conflict of interest that may bias study design, analysis, or reporting toward favorable results
Industry-funded studies have been shown to be more likely to report positive outcomes than independently funded ones, potentially due to biases in design, data analysis, or selective reporting.
Question 7: A doseāresponse relationship between dark chocolate consumption and blood pressure reduction strengthens which type of causal inference framework?
- Bradford Hill criteria for causation (Correct answer)
- Null hypothesis significance testing
- Bayesian probability estimation
- CONSORT reporting guidelines
Correct answer: Bradford Hill criteria for causation
Bradford Hill criteria include 'biological gradient' (doseāresponse), and finding that more chocolate produces greater BP reduction is one piece of evidence supporting a causal link.
Superfoods Research & Evidence-Based Practice 4
The GRADE system used to evaluate superfood research evidence ranks 'RCT evidence' as high quality by default, but can downgrade it for which reason?