Hypertension, characterized by elevated arterial blood pressure and persistent high blood pressure, can lead to stroke, heart disease, kidney disease, and other derived diseases. It can be divided into primary and secondary hypertension (Rivas et al., 2021). Essential hypertension is an elevation in blood pressure that is not caused by any other disease, whereas secondary hypertension is an increase in blood pressure caused by other diseases.

As shown in Figure 1 , the coverage of hypertension is extensive, as different groups present with differing symptoms and types. Approximately 20-30% of childhood hypertension is primary, while 65-80% is secondary. Hypertensive syndrome of pregnancy, also known as pregnancy poisoning or pre-eclampsia, is unique to pregnant women and typically appears around 20 weeks gestation or within two weeks postpartum (Ives et al., 2020). Senile systolic hypertension, which refers to systolic blood pressure higher than normal levels and normal diastolic blood pressure in elderly individuals over 60 years old, is an independent condition and a risk factor for senile vascular diseases and stroke (Hu et al., 2013).

The host microbiome is a complex ecosystem consisting of bacteria, eukaryotes, viruses, and archaea which coexist on tissue surfaces and within the body ( Figure 2 ). These microbial communities play important roles in physiological activities such as digestion, metabolism, immune response, compound synthesis, toxin elimination, and even the pathogenesis of certain diseases (Gasaly et al., 2021). Intestinal microorganisms have been found to have a role in the occurrence and maintenance of hypertension. When researchers studied a model of spontaneous hypertension, they noted a series of changes in intestinal physiology, such as changes in intestinal microbes and the amount of tight junction proteins in the intestinal wall (Kim et al., 2018). The imbalance of intestinal microorganisms, combined with the increased inflammation, leads to abnormal sympathetic nerve and intestinal function, which can ultimately lead to the development of hypertension (Guyenet et al., 2020). Li et al. (2021) conducted bacterial genome analysis and fecal microbiome transplantation to find that an abnormal gut microbiota richness was significantly associated with hypertension. The research results of Liu et al. (2018) indicated that the number of Bifidobacterium and Bacteroides decreased, while the number of Eubacillus rectalis increased in the intestinal tract of patients with hypertension, and that the content of intestinal flora was correlated with blood pressure.

Hypertensive individuals and animals have been observed to have reduced bacterial diversity in their gut microbiome, disordered microbial structure and function, and the fermentation end products often altered (Li et al., 2021). This imbalance of intestinal flora and the change of metabolites are key factors in controlling blood pressure. With the development and widespread use of metagenomic sequencing and metabolomics, the relationship between metabolites of intestinal flora and human cardiovascular diseases has been brought to the attention of public. In particular, recent studies on metabolite have found that trimethylamino-N-oxide (TMAO) contributes to the promotion of atherosclerosis through the production of pro-inflammatory cytokines (TNF-α and IL-1B), the reduction of anti-inflammatory cytokines (IL-10), especially the excessive reaction of platelets led to the formation of thrombus (Livshits and Kalinkovich, 2019). Calderón-Pérez et al. (2020) studied gut microbes by targeting microbial metabolites short chain fatty acids (SCFA) and TMAO in plasma and stool. The results of their study showed that there were significant differences in the types and richness of intestinal flora between normal people and hypertensive patients.

Based on the microbiome and microbial metabolites, it is possible to distinguish individuals with hypertension from those without before treatment with drugs. Furthermore, this may be used to initially identify individuals with hypertension symptoms.

Probiotics are live, non-pathogenic microorganisms that, when present in sufficient amounts, may confer health benefits on the host (Salminen et al., 2021). The application of probiotics is commonly achieved in the form of raw materials for functional foods (Rashidinejad et al., 2022). Functional foods are defined as food with specific nutritional and health-promoting functions, meant for certain people with the purpose of regulating body functions (Gul et al., 2016). These include foods for improving body constitution, preventing certain diseases (such as hypertension, diabetes, and coronary heart disease), and restoring health. However, functional foods differ from drugs in that they are not used for treatment, and cannot replace medication for patients. In addition, functional foods must be non-toxic or, at least, exhibit toxicity levels below the threshold set by modern toxicology, meaning that they pose no significant risk of toxic side effects with regular consumption. When compared to current antihypertensive drugs, functional foods can be used to relieve mild symptoms and prevent elevated blood pressure, thus alleviating or counteracting the disease without the risk of developing depression associated with β-receptor blockers (Yeo et al., 2009).

In recent years, probiotics have been proposed as an alternative to antimicrobials and as an adjunct therapy for various chronic diseases (Tsai et al., 2019). Microorganisms directly participate in the metabolic mechanisms of certain diseases, or produce metabolites that affect certain diseases (Hou et al., 2022), such as histone deacetylase inhibitor metabolites that modify cancer susceptibility and lesions. The metabolites produced by probiotics upon entering the body, commonly known as prebiotics, can have direct effects on atherosclerosis (Vourakis et al., 2021), hypertension (Muralitharan et al., 2020), heart failure (Kaye et al., 2020), Type-2 diabetes (Iatcu et al., 2021), and other diseases. Probiotics can directly or indirectly affect host physiology through the production of prebiotics, such as TMAO, SCFA, secondary bile acids and indoxyl sulfate. These metabolites can stimulate a variety of signaling pathways that control physiological processes.

Probiotics have become increasingly popular due to their beneficial properties as functional foods and are now frequently used in everyday life. Besides traditional frozen dairy products, bread and snack products provide new opportunities for the development of probiotics, such as probiotic nuts, probiotic wafer cookies launched in the Chinese market, and energy bars with probiotics added in the Australian market. In the past, probiotics were often fragile and had to be refrigerated, making them difficult to be incorporated into products other than dairy products. However, with the increasing demand, more and more tolerant probiotics have been screened out, such as adapting to extreme pH, high temperature, low temperature, or high pressure. This expands the possibilities for probiotics to be used in frozen foods, hot drinks, and snacks. The growing market of probiotic consumption further indicates people’s newfound understanding of probiotics. Japan, which was the first country to commercially utilize probiotics, has put a lot of emphasis on the probiotic market. Lactic acid drinks containing probiotics have been used in Japan since the 1970s, making it one of the largest consumers of probiotic products in the world. Meanwhile, some enterprises have also emerged in the probiotic market in other countries as listed in Table 1 . These enterprises have a long history and rich experience in the production and processing of probiotics.

The incidence of hypertension was highest in individuals aged over 40 and increased with age (Wang et al., 2020). According to an analysis of Statistics Canada statistics, the incidence of high blood pressure is positively correlated with increasing age (DeGuire et al., 2019). A national survey on hypertension in France in 2015 found that hypertension was prevalent among individuals aged 18 to 74, with the incidence in men being slightly higher than that in women (Vallée et al., 2020). For middle-aged hypertensive patients aged 30 to 50 years, the manifestation was increased diastolic blood pressure, along with an increase in systolic blood pressure. Simple diastolic hypertension was more common in middle-aged men. Weight gain was associated with increased peripheral vascular resistance and normal cardiac output. For elderly hypertension patients aged over 65 years, simple systolic hypertension was the most common type (Briasoulis et al., 2014). Epidemiology has demonstrated that systolic blood pressure increases with age, while diastolic blood pressure gradually decreases after 55 years of age (Jennings et al., 2019).

People who consume excessive amounts of salt have been found to have an increased incidence of hypertension (He et al., 2020). High-sodium diets have been linked to changes in various proteins involved in calcium stabilization and heart muscle contraction, and excessive sodium intake has been associated with hypertension, stroke, and various cardiovascular diseases. Notably, the salt-sensitive population demonstrates an unusually sensitive renal response to salt intake. This is due to the abnormal overreaction of the sympathetic nervous system, coupled with weakened inhibition of the renin-angiotensin axis, which results in the blocking of nitric oxide (NO) synthesis by endothelial cells, leading to increased vascular resistance and hypertension in the salt-sensitive population. Poor dietary habits are a major cause of hypertension. A study on five dietary patterns for middle-aged and elderly people in the rural areas of Beijing, Northern China, revealed that an irrational dietary pattern characterized by high consumption of refined wheat, meat, poultry and alcoholic beverages was positively correlated with blood pressure (Li et al., 2023).

Obesity is associated with an increased incidence of hypertension. As shown in Figure 3 , this can be attributed to several changes in endocrine, inflammatory, and endothelial cell levels (Seravalle and Grassi, 2017; Xiao and Harrison, 2020; Cober et al., 2022; Fernandes-Rosa et al., 2023). Adolescent primary hypertension is largely driven by the increase in visceral fat deposition, which triggers the typical biological maturation and metabolic abnormal syndrome, and ultimately leads to the release of adrenaline (Manosroi and Williams, 2019). The mechanisms underlying obesity-related hypertension include the release of leptin, adipokines, and inflammatory factors, which promote vascular inflammation, damage endothelial function, and contribute to the proliferation, migration and foam cell formation of vascular smooth muscle cells (VSMC), platelet adhesion and aggregation, and atherosclerosis, resulting in elevated blood pressure (Supriya et al., 2018; Recinella et al., 2020).

Hyperleptinemia and hypoadiponectinemia are common among obese hypertensive patients (Perrotta et al., 2019; Gruber et al., 2021). Elevated leptin levels have been found to increase oxidative stress, reduce NO biosynthesis, and promote sodium reabsorption, resulting in increased arterial blood pressure (Bełtowski, 2006). On the other hand, adiponectin has been shown to have a protective effect on the cardiovascular system, increasing insulin sensitivity and inhibiting inflammation (Cohen et al., 2022). The plasma adiponectin levels were also found to be negatively correlated with blood pressure. Furthermore, most of the body is covered with fat outside of the blood vessels. This adipose tissue can release lipid-derived vasodilator factors to act on the potassium channels of the vascular smooth muscle, causing vasodilation. However, this lipid-derived vasodilation response is impaired in hypertension. In one study, adipose tissue and VSMC were co-cultured, and the expression of angiotension II (Ang II) receptor and RhoA and Rho kinases were found to be increased in the VSMC. These signaling molecules are known to play an important role in vascular remodeling and blood pressure regulation (Savoia et al., 2005). Moreover, when the area of the visceral fat was further increased, various metabolic disorders and cardio-renal vascular target organ damage began to emerge successively.

Hypertension is a complex polygenic disorder, with many genes influencing its development (Zhao et al., 2013). If both parents have high blood pressure, their children are at higher risk of developing hypertension (Weijmans et al., 2015). Hypertension may be inherited through two different mechanisms: gene dominant inheritance and polygene association inheritance (Stoll et al., 2018; Teixeira et al., 2018). Advances in molecular biology have offered further insight into the pathogenesis of hypertension in these conditions, elucidating how several risk genes and environmental factors interact with each other and ultimately lead to hypertension (Kawarazaki and Fujita, 2021). In recent years, genome-wide association studies have identified more than 100 single nucleotide polymorphisms associated with blood pressure phenotypes and mutations in multiple single genes that lead to diseases with elevated blood pressure, such as glucocorticoid-inhibiting aldosteronism and Gordon syndrome (Padmanabhan et al., 2017; Mabillard and Sayer, 2019; Zennaro et al., 2020). Mutations in some genes are also associated with increased blood pressure (Matsuo et al., 2004; Dungan et al., 2009; Zhang et al., 2015; Fan et al., 2017). Further research into the genetic and DNA expression of hypertension may provide new pathways for blood pressure regulation and new ideas for hypothesized drug targets for hypertension.

Studies have found that people who live in noisy train stations or downtown areas have a higher risk of hypertension compared to those who reside in quiet, rural areas (Lee et al., 2019). This is due to the increase in norepinephrine secretion and increased heart rate caused by noise, as well as the reduction in blood magnesium, a protective agent for heart muscle, leading to a higher incidence of coronary heart disease (Münzel et al., 2017). Experimental evidence has demonstrated that in exposed noise environments, the walls of capillaries are more prone to deformation, which slows down blood flow and can damage both the myocardial and vascular systems. Hence, noise and other living environment factors can also significantly increase the risk of developing hypertension (Münzel et al., 2014; Hahad et al., 2019). High altitude and cold living environments are additional risk factors for hypertension (Shen et al., 2017; Chen and Sun, 2017).

Numerous clinical trial data currently support the use of medication or low doses of clothiazone, angiotensin receptor blockers, and patient-specific therapy to reduce blood pressure. However, the efficacy of these new treatment strategies for patients with diabetes, chronic kidney disease, pregnancy, and other conditions remains to be further discussed. For example, in hypertensive women, ACE inhibitors and ARBs may need to be discontinued during pregnancy, and other options such as methyldopa and labetalol may be worth considering (Lu et al., 2018). In addition, many kinds of antihypertensive drugs have been found to have many side effects. The side effects of some common antihypertensive drugs are summarized in Table 2 (Laurent, 2017).

Gut microbial richness and diversity have been linked to hypertension in both animals and humans, and dysregulation of the microbiome increases the risk of developing the condition (Yang et al., 2015; Li et al., 2017b). Clinical studies suggest that the use of probiotics can lead to moderate to significant reductions in blood pressure (Yuan et al., 2023). For instance, consuming beverages containing Lactobacillus plantarum for a period between 1-2 months has been found to reduce vascular systolic blood pressure, fibrinogen, and interleukin levels in healthy participants. Furthermore, several clinical trials for hypertension have reported that the use of Lactobacillus-fermented milk significantly reduced blood pressure (Aoyagi et al., 2017). In recent years, the mechanism of probiotics in hypertension has been the subject of many studies, and the impact of probiotics on blood pressure levels has been increasingly recognized. The studies related to probiotics in the treatment of hypertension are listed in Table 3 . It is clear from these studies that the treatment of hypertension relies not only on a single probiotic, but also on a combination application of probiotics. Moreover, the rich types of functional foods also provide a variety of carriers for the probiotics. As shown in Figure 4 , four probiotics are used as adjunctive therapy for hypertension and their mechanisms of action.