# Unlocking Wellness: Probiotics as Key Drivers in Functional Food Innovation and Health Promotion
## 3 The Function of Probiotics
### Metabolic Disease Intervention  
Metabolic diseases, including obesity, T2 DM, non-alcoholic fatty liver disease (NAFLD), and hypertension, have emerged as major public health challenges globally [59]. To systematically assess the effects of oral probiotics on these diseases, [PERSON] et al. [60] reviewed 105 randomized controlled trials involving 6826 subjects sourced from the Medline, EMBASE, and Cochrane databases. The study results demonstrated that probiotics significantly reduced body weight, BMI, waist circumference, body fat mass, and visceral adipose tissue mass in overweight but non-obese individuals. Additionally, in patients with T2 DM, probiotics significantly reduced fasting blood glucose, glycosylated hemoglobin, and insulin levels. In patients with NAFLD, probiotics significantly lowered alanine aminotransferase and aspartate aminotransferase levels. These ameliorative effects were particularly prominent in mixtures containing _Bifidobacterium_ (e.g., _B. breve, B. longum_), _S. Thermophilus_, and _Lactobacillus_ (e.g., _L. acidophilus, L. casei, L. delbrueckii_).  
Probiotics can intervene in metabolic diseases through multiple mechanisms. First, they can activate the Adenosine 5\({}^{\prime}\)-monophosphate (AMP)-activated protein kinase pathway via SCFAs to promote fat oxidation and stimulate the secretion of the satiety hormones glucagon-like peptide-1 and peptide YY, thereby reducing appetite [61]. Additionally, probiotics stimulate Glucagon-like peptide-1 secretion via SCFA-mediated signaling from intestinal L cells, which promotes insulin secretion and inhibits glucagon release, thereby improving glycemic control, as shown in Figure 2[62]. Simultaneously, probiotics can inhibit \(\alpha\)-glucosidase activity, delay carbohydrate absorption, reduce postprandial blood glucose peaks, and further enhance glycemic control in patients with T2 DM [63]. To improve NAFLD, probiotics enhance hepatic lipid metabolism by regulating bile acid metabolism, increasing bile acid synthesis and secretion, and promoting cholesterol excretion. Meanwhile, probiotics protect liver cells from damage by reducing oxidative stress and inflammatory responses through their antioxidant and anti-inflammatory effects [64]. Moreover, probiotics exert antihypertensive and cardiovascular protective effects through various mechanisms. Probiotics can regulate the metabolic activity of the intestinal microbiota, promote the production of SCFAs, activate G-protein-coupled receptor 41/43, and subsequently promote the release of nitric oxide, which effectively dilates blood vessels and thereby lowers blood pressure [65]. Concurrently, probiotics can inhibit the activity of angiotensin-converting enzyme and reduce the generation of angiotensin II, further reducing blood pressure [66]. Additionally, by regulating cholesterol metabolism, probiotics reduce lipid deposition on blood vessel walls and lower serum total cholesterol and low-density lipoprotein cholesterol levels, thereby alleviating atherosclerosis and reducing the risk of cardiovascular disease [67].