GMAT Focus EditionVerbal ReasoningMedium
A recent study found that individuals who regularly consume fermented foods, such as yogurt and kimchi, exhibit lower rates of anxiety. Researchers concluded that the probiotics in these foods positively impact gut-brain axis communication, thereby reducing anxiety. Which of the following, if true, would most strengthen the researchers' conclusion?
- AParticipants in the study who consumed fermented foods also reported engaging in more regular physical exercise.
- BA separate study found that individuals with anxiety disorders often have an imbalanced gut microbiome.
- CMany fermented foods are also rich in vitamins and minerals known to support overall health.
- DSome individuals experience digestive discomfort when consuming large amounts of fermented foods.
Show answer & explanationAnswer & explanation
Correct answer: B. A separate study found that individuals with anxiety disorders often have an imbalanced gut microbiome.
The researchers conclude that probiotics in fermented foods reduce anxiety by impacting gut-brain axis communication. Option A strengthens this conclusion by providing additional evidence for a link between gut health (imbalanced microbiome) and anxiety, which aligns with the proposed mechanism of action (probiotics improving gut-brain axis communication).
Why the other options are wrong
- A. This introduces a confounding variable (exercise) that could also explain lower anxiety, thus weakening, not strengthening, the original conclusion.
- C. This introduces an alternative explanation for overall health benefits, not specifically strengthening the link between probiotics, gut-brain axis, and anxiety.
- D. This describes a side effect, which is irrelevant to whether probiotics reduce anxiety.
Strengthening Causal Mechanisms
To strengthen a causal claim, provide additional evidence that supports the proposed mechanism by which the cause leads to the effect, or rule out alternative causes.
- Focus on the 'how' and 'why' of the relationship.
- Look for evidence that confirms intermediate steps or associated conditions.
- Eliminating alternative explanations also strengthens the original claim.
Memory trick: Adding a missing piece to the puzzle makes the picture clearer.