Do fermented vegetables like kimchi help with stress?
Studies into fermented products and probiotics show a mixed picture for anxiety and stress. For kimchi specifically, no research yet exists.
Kimchi as a specific product has not been studied for stress relief. What has been studied are probiotics and fermented foods more broadly, and even there the picture is mixed. A combined look at 42 studies in people found some evidence of improvement in depression, but for anxiety and other stress-related complaints the role of probiotics and fermented products remains unclear.
The most direct research into stress and fermented products in people was carried out with students. They were given fermented milk containing a specific probiotic bacterial strain for four weeks. Their gut bacteria stayed somewhat more stable during stressful exam periods than those of students who did not drink it, and a higher presence of a particular bacterial species was linked to slightly lower anxiety scores. However, the effects on actual stress levels were limited, and this was a secondary analysis of the data rather than the main aim of the research. In addition, two of the authors were employed by Danone, the company that makes the product, which makes this result less independent.
Another possible line of inquiry is the reduction of inflammation. Several studies have found that probiotics and fermented foods lower certain inflammation markers in the blood, which could offer an explanation for mental health benefits. Whether the same applies to fermented vegetables, and whether it makes any difference to how stressed healthy, ordinary people feel, has not yet been shown.
Eating kimchi as part of a varied diet is certainly not harmful, but as a specific remedy for stress it currently has no scientific backing. If stress or anxiety is a serious problem for you, it is wise to discuss that with your doctor.
This answer draws on a combined look at 42 studies in people examining probiotics, prebiotics and fermented foods in relation to psychiatric conditions, and on one study in students using a specific probiotic drink. The researchers behind the combined review themselves emphasise that the evidence for most psychiatric applications is still insufficient. The student study is limited because the stress outcomes were a secondary analysis, and because two authors are connected to the manufacturer of the product being studied. Kimchi as a product was not directly studied in any of these studies.