# The Role of Fermented Vegetables as a Sustainable and Health-Promoting Nutritional Resource
## 5 Influence of Vegetable-Fermented Foods on Mental Health
For instance, sauerkraut, which is abundant in LAB, has been demonstrated to trigger a chemotactic  
Figure 2: Hypothetical role of functional components of fermented vegetables in the GM and the brain, as well as related beneficial consequences (based on [PERSON] et al. [330]). response in monocytes through D-phenylacetic acid, a strong agonist of the HCA3R receptor [333]. In addition, microbial surface molecules and microbial metabolites (i.e., SCFAs, methylamines, bile acid, and amino acid metabolites) are involved in the integrity of the intestinal epithelial barrier and of the BBB [328; 334; 335; 329]. Only a few interventions on the neurological benefits of fermented vegetable foods have been conducted recently. These studies on the influence of fermented vegetable-based products, such as miso, natto, tempeh, tofu, and other types of fermented vegetables, showed that a greater intake of soy-based products positively correlated with improved cognitive function in female participants [336]. This consumption was also linked to the mitigation of age-related memory impairment [327] and cognitive deterioration [319]. The isoflavone constituents of fermented soy products are known to exhibit estrogenic protective properties, potentially contributing to the neuromodulatory effects of these products in women [336]. Conversely, certain studies have underscored negative outcomes associated with tofu consumption, linking it to diminished cognitive performance in multiple cross-sectional observational investigations [337; 338]. It has been posited that formaldehyde, utilized in tofu production to enhance shelf stability, may lead to oxidative damage, thereby influencing cognitive decline [337]. Table 4 shows several clinical studies on the relationship between fermented vegetable food consumption and mental health outcomes. \begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Reference** & **Fermented Vegetable** & **Intervention** & **Outcomes** \\ \hline
[336] & Tofu, miso, and natto & \(N=776\) (403 men and 343 women). & Soybean and isoflavone consumption was associated with lowered cognitive impairment in elderly women and no impact in men. \\ \hline
[337] & Tofu and tempeh & \(N=719\) (52–98 years of age). & Consumption of higher amounts of tofu was associated with memory decline. Tempeh consumption was related to better performance in memory-associated tasks. \\ \hline
[338] & Tofu & \(N=521\) (\(>\)50–95 years of age). Of the total, \(N=115\) were patients with dementia. & High tofu consumption was negatively associated with verbal learning, immediate recall, and increased cognitive impairment. \\ \hline
[339] & Tofu and tempeh & \(N=142\) (56–97 years of age). & Tofu and tempeh consumption in rural Javanese elderly both have a positive association with immediate recall memory. \\
[339] & Tofu and tempeh & \(N=142\) (56–97 years of age). & These findings are significant in those with an average age of 67 years, but not in those with an average age of 80 years. \\  & & & Estrogen compounds present in fermented vegetables can exert positive effects on verbal memory, but not in older men and women. \\ \hline
[340] & Tofu, miso, and natto & \(N=1105\) (\(>\)65 years of age). & Soy-based food intake was negatively associated with cognitive impairment. \\ \hline
[341] & Fermented algae _Laminaria japonica_ & \(N=60\) (32 treated and 28 placebo). 6 weeks (\(>\)70 years of age). & Treatment increased working memory and visual and spatial reasoning in the intervention group. Algae consumption improved neuropsychological test scores. \\ \hline
[342] & Fermented soybean & \(N=100\) MCI (50 treated and 50 placebo). 12 weeks. & Increase cognitive function in treated group. \\ \hline
[343] & Miso and natto & \(N=72,624\) mother and child pairs. 9 months. & Reduced risk of inadequate sleep in infants at 1 year of age from mothers with high miso intake during pregnancy. \\ \hline \hline \end{tabular}
\end{table}