# Unlocking Wellness: Probiotics as Key Drivers in Functional Food Innovation and Health Promotion
## 4 Application of Probiotics in Functional Foods
### Plant-Based and Fruit and Vegetable Products
#### 4.2.2. Probiotic Fermented Soy Products  
Soy milk is rich in oligosaccharides, which serve as prebiotics and provide a high-quality growth environment for LAB, particularly bifidobacteria [93]. Importantly, probiotics can convert soy isoflavvage glycosides, a functional component, into biologically active isoflavunes [110]. [PERSON] et al. [111] determined the isoflavyeoside content in soy milk fermented with a single strain. The results showed that soy milk not only maintained high probiotic activity (10\({}^{7}\)-10\({}^{9}\) CFU/mL) but also significantly increased the content of soy \begin{table}
\begin{tabular}{c c c} \hline \hline
**Probiotic Fermented Milk Products** & **Tested Strains** & **Reference** \\ \hline High-protein drink, pure probiotic & _Lactobacillus acidophilus_, _Bifidobacterium lactis_, _Lactobacillus_ & [95] \\ fermented milk & _paracasei_, _Streptococcus thermophilus_ & [96] \\ Compound lactobacillus beverage & _Lactobacillus_, _Streptococcus thermophilus_, _Lactobacillus_ & [97] \\ Probiotic fermented milk with & _acidophilus_ and _Bifidobacterium_ & [98] \\ compound fruit and vegetable juice & _Lactobacillus_, _Lactobacillus_ & [99] \\ Probiotic fermented goat milk & _Lactobacillus_, _Birudobacterium_ & [100] \\ Double-protein probiotic yogurt & _Lactobacillus_, _Streptococcus thermophilus_ & [101] \\ Probiotic yogurt ice cream & _Streptococcus thermophilus_ & [102] \\  & _DMLD-H1_ & \\ Compound probiotic fermented milk & _Lactobacillus paracasei PC-01_, _Bifidobacterium Lactobacillus_ & [103] \\  & _Probio-M8_ & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Probiotic fermented milk products and their strains. isoflavone glycosides. Isoflavone glycosides act as phytoestrogens to regulate endocrine secretion bi-directionally [112]. In cases of estrogen deficiency, isoflavones exhibit mild estrogenic activity, alleviating menopausal symptoms such as hot flushes, night sweats, and osteoporosis. Conversely, in cases of estrogen excess, they competitively bind to receptors to reduce the risk of breast cancer. In a study where rats with 2-Amino-1-Methyl-6-Phenylimidazo [4,5-B] Pyridine chemically induced mammary tumors were fed soymilk alone, _L. casei_ alone, and a combination of soymilk and _L. casei_, the results showed that tumor incidence was reduced in the soymilk group, and tumor volume was decreased in the _L. casei_ group. Moreover, the combination group exhibited significantly reduced tumor incidence and volume. _L. casei_ exerts its anticancer effect by enhancing natural killer cells' activity, which is significantly enhanced when combined with soymilk [113]. Therefore, the use of probiotics can complement the cancer prevention function that cannot be achieved when using soy milk alone. Natto, a traditional Japanese fermented food, is made from soybeans fermented by _Bacillus subtilis_[114]. Natto kinase (NK), a key functional component, effectively dissolves fibrin. Furthermore, natto contains other bioactive compounds that collectively contribute to various health benefits, including improved blood circulation and reduced cardiovascular disease risk [115]. However, the odor and taste of natto may not be acceptable to most people. Thus, adjustments are made to improve its sensory properties and acceptability, such as modifying the fermentation strain formula and fermentation conditions. Additionally, natto contains biogenic amines, which may adversely affect human health when ingested in excess [116]. [PERSON] et al. [117] conducted mono-, bi-, and tri-bacterial fermentations using _B. subtilis_ GUTU09 (B9) in combination with _Lactobacillus_, _Bifidobacterium_, and _Trichoderma_. The results showed that bio-fermentation (especially the combination of B9 and _Trichoderma_) exhibited higher NK and protease activities under co-fermentation conditions; additionally, it significantly reduced biogenic amine content (total biogenic amine decreased to 16.16 mg/kg) and improved the flavor and texture of natto.