Fermented foods are popular today, as evidenced by the many popular press articles (see below) touting their benefits.
At the same time, science is emerging on probiotic administration and improved human brain function (see previous post Can Probiotics Help Your Brain? February 5, 2013). One recent study (Pärtty et al. 2015) linked probiotic administration to infants to a lower risk of development of Asperger-like symptoms or attention deficit hyperactivity disorder at age 13. Another study (Steenbergen et al. 2015) showed that probiotics may help reduce negative thoughts associated with sadness. Selhub et al. (2015) explore the relationship between fermented foods, microbiota and mental health in a recent review.
So I wasn’t surprised to see a new study that examined the specific relationship between fermented food consumption and social anxiety (Hilimire et al. 2015). Whereas other studies focused on controlled, probiotic interventions, this study sought to determine if there was a relationship between social anxiety and choosing to consume fermented foods. Using the readily available subject population of Introductory to Psychology students, the authors conducted a cross sectional study to test the hypothesis that young adults high in neuroticism will demonstrate lower levels of social anxiety if their fermented food intake is high.
732 ethnically diverse, young adult students completed an electronic survey that measured social phobia and anxiety (SPAI-23 inventory), exercise frequency and food fermented food intake frequency. Food intake was measured by recall over past 30 days on 10 items: All fruits and vegetables, yogurt, kefir, soy milk, miso soup, sauerkraut, dark chocolate, microalgae containing juices, pickles, tempeh and kimchi.
The study found that a lower level of social anxiety was positively and independently associated with consumption of fermented foods, total fruit and vegetable consumption and more frequent exercising. Also, subjects expressing higher neuroticism showed fewer social anxiety symptoms when they consumed fermented foods.
Limitations to this study should be clear. For one, some of the surveyed foods are not fermented (all fruits and vegetables and soy milk), some may be fermented but commonly do not contain live microbes when sold (pickles, miso soup, sauerkraut, dark chocolate) and some may contain live microbes but not be fermented (microalgae containing juices). So it’s not clear what the unifying characteristic of the foods that were surveyed really is. Furthermore, food recall as a method to assess intake is not reliable. Most importantly, this study provides evidence of an association, not causality. Therefore it is not possible to know from this study if increasing intake of fermented foods would impact anxiety.
Even acknowledging these limitations, the authors suggest that, considering the low risk of exercise and fermented foods/probiotics, they should perhaps be considered as a complement to current anti-anxiety strategies.
This is an intriguing finding that warrants further investigation.
Popular press articles about fermented foods: