Vascular calcification (VC) is the abnormal deposition of calcium and phosphorus in the walls of blood vessels (1). Although studies on VC have primarily focused on coronary artery calcification (CAC), the multi-ethnic study of atherosclerosis (MESA) study suggests that abdominal aortic calcification (AAC) occurs earlier and is a more effective prognostic marker than CAC, independent of CAC scores (2, 3). Current studies have established a strong correlation between AAC and cardiovascular events as well as mortality (3–5), but another study still believed AAC is an underestimated cardiovascular disease risk factor (6). As the AAC severity increases, the risk of fatal cardiovascular events and mortality also increases significantly (7, 8).

Since the progression of VC is difficult to reverse, prevention and treatment are extremely important (9). Although VC is often considered the advanced stage of atherosclerosis (AS) (3), current medications targeting AS have shown limited efficacy in treating VC (10). Several drugs, such as bisphosphonates, calcium channel blockers, vitamin K, and dietary magnesium, may have therapeutic potential, but there is still a lack of robust clinical evidence (3, 11, 12). To date, there are no approved treatment strategies for preventing or managing AAC (13).

Adopting healthy diets is widely recognized as an effective approach to preventing cardiovascular diseases (CVD) (14). Healthy diets such as anti-inflammatory diets (15), Mediterranean diets (14), and DASH diets (16), decreased the risk of having AAC. These studies mainly focused on the role of food ingredients but ignored the impact of dietary live microbes. Studies have found that diets can influence gut flora composition and metabolites (17) and impact disease susceptibility (18, 19). Therefore, there is growing interest in the health effects of live microbes in diets. Recently, Sanders et al. (20) used the National Health and Nutrition Examination Survey (NHANES) database to assess the number of live mircrobes in various foods. They also discovered live microbe-rich diets improved health outcomes, including lower BMI, blood pressure, lipids, glucose, insulin, and inflammation level (21). These benefits from dietary live microbes may prevent diseases. Based on NHANES data and Sanders’ dietary live microbe classification system, we explored the association between dietary live microbes and AAC.

To our knowledge, this is the first study examining the association between dietary live microbe intake, assessed through NHANES 24-h recall data, and AAC within a nationally representative sample of US adults. Our findings indicated that compared to the low intake group, the high dietary live microbe intake group was associated with lower AAC scores and lower risk of severe AAC. The observed relationship persisted even after adjustment for relevant confounders, including demographics, bone metabolism markers, kidney function, other laboratory tests, comorbidities, drug use, and energy intake. In the subgroup analysis, the benefit of increased live microbe intake was particularly pronounced among age above 60 years, eGFR ≥ 60 ml⋅ (min × 1.73 m²) ^–1 and those with cardiovascular risk factors like hypertension, smoking, alcohol use, overweight, and diabetes. These findings underscored the potential therapeutic role of dietary live microbes, especially for individuals facing heightened cardiovascular risks, and these deserved further exploration and validation in future research.

Our findings are consistent with previous research, reinforcing the potential benefits of dietary interventions. A dietary intervention randomized controlled trial (RCT) included 90 patients with CVD risk factors who received probiotic alone, lactofermented Annurca apple puree (lfAAP), or unfermented Annurca apple puree (AAP) for 8 weeks according to a 1:1:1 allocation. At the end of the intervention, compared with other groups, the treatment effect of the lfAAP group was most obvious; HDLC increased by 61.8% compared with before intervention, while trimethylamine N-oxide (TMAO) decreased by 63% (28). Moreover, it enhanced the bioavailability of dietary polyphenols in the gut to exert antioxidant and anti-inflammatory cardiovascular benefits (28–30). A recent study found that participants who consumed medium or high levels of dietary live microbes showed better cognitive function compared to those with low intake, particularly for those with certain medical conditions like CVD, diabetes, and hypertension (23). Taking into consideration recent research, the potential health advantages associated with augmenting dietary live microbe intake, spanning improvements in blood pressure, glucose and lipid metabolism, cognitive function, intestinal nutrient absorption, and its influence on the intestinal flora, may indeed form a fundamental strategy for mitigating the risk of severe AAC (21, 23).

Previous studies have observed changes in the gut flora of VC patients. An observational study investigated differences in gut flora composition among chronic disease patients with varying degrees of aortic arch calcification (AoAC) (31). Individuals with the highest AoAC scores displayed a significant decrease in α-diversity along with a heightened prevalence of Clostridia species; those with lower AoAC scores exhibited a more favorable microbial profile, characterized by a higher abundance of beneficial bacteria such as Agathobacter (31). In another study involving 73 hemodialysis patients, notable distinctions in gut flora were discerned across various VC groups (32). Escherichia coli exhibited a positive correlation with VC and emerged as the primary contributor to VC progression; conversely, Ruminococcus, the bacterium recognized for producing short-chain fatty acids (SCFAs), displayed a negative correlation with VC and had the second most significant impact on VC (32). These SCFAs can promote tissue repair, regulate immunity, and are closely related to VC (33). In the rat vascular calcification model induced by vitamin D3 and nicotine, it was found that Akkermansia supplementation can enhance intestinal flora diversity, promote SCFA production, reduce inflammation, and ultimately alleviate VC (9). Consequently, these findings suggest a potential role for the gut flora in the development and progression of AAC.

One plausible explanatory mechanism for the observed association involves the food-gut-health axis (34). Diet can exert selective pressure on the gut flora, determining which microorganisms can colonize, persist, or become extinct in the gastrointestinal tract (35). It therefore plays a key role in shaping the composition and diversity of the gut microbiota (35, 36). Fermented Foods, fresh fruits and vegetables are an important source of probiotics, including Lactobacillus, Bifidobacterium, and Escherichia coli (37, 38). Probiotics exert anti-vascular calcification effects by acting on the intestines and throughout the body (39). First, probiotics play a pivotal role in restoring microbial equilibrium by upholding the integrity of the intestinal epithelial barrier and facilitating rebalancing (40). This maintenance protects the intestinal barrier, reduces the overpopulation of harmful bacteria, and prevents the production and leakage of harmful bacterial by-products into the circulation (41). It can regulate the expression of specific microRNAs and inhibit synthetases to reduce the production of TMAO metabolites (42, 43). Furthermore, the beneficial effects of probiotics extend to regulating the absorptive function of the intestines (44). They aid in the conversion of inorganic zinc into its organic form, thereby promoting its absorption—an action that contributes to the fight against AS and VC (44). Moreover, probiotics can promote the absorption of nutrients such as polyphenols, magnesium, vitamin D, vitamin C, and vitamin E (29, 45, 46). Not only that, it can inhibit the absorption of heavy metals and cholesterol in the intestine, and the heavy metals are thought to promote AS and calcification (47). Additionally, probiotics contribute to the production of substances associated with the prevention of VC, including vitamin K, and SCFAs (33, 48). These findings underscore the diverse and impactful role of probiotics in promoting gut-health and their potential implications for broader systemic wellbeing.

Our focus on habitual dietary microbe intake, rather than probiotic supplements, enhances the translational potential of these findings. A sustained, stable, and long-term dietary regimen significantly influences the composition and functional dynamics of the gut microbiota (49), and the impact of probiotics tends to be relatively transient (50, 51). However, we cannot directly recommend that the general population increase their intake of dietary live micorbes. Because its long-term effects are unknown, and its safety needs to be considered, especially for certain special groups including those with multiple severe infections, immune deficiencies, or gastrointestinal inflammation (52). In addition, the effects of dietary interventions enriched with dietary live microbes may vary by strain. Therefore, it may be important to emphasize tailoring the approach to individual health status and goals. Nonetheless, current evidence suggests that increasing the intake of microbe-rich foods may be a valuable strategy for improving cardiovascular health. It may have practical implications for public health and dietary guidelines. But longitudinal studies and RCTs are necessary.

There are several limitations in this study. First, in this cross-sectional study we observed the association, but causation cannot be established. Second, 24-h dietary recall data may be inaccurate due to recall bias and dietary live microbes can be affected by transportation, storage, and cooking. Third, Sanders’ dietary live microbe classification system may have lower accuracy than direct measurement. However, direct measurement requires a long time and huge expenditure, which limits its application. Fourth, the rough grouping of microbial diets may introduce estimation errors in assessing microbial intake. Fifth, our study is based on the US population, and the generalizability of the results to other populations worldwide may be limited. Sixth, although NHANES covers most of the US population through complex sampling, it does not include the hospitalized population. This results in under-assessment of critically ill patients. Seventh, despite adjusting for confounding factors, there may still be unknown confounders that have not been accounted for. Therefore, our research results should be treated with caution and can not directly guide the diet of the population. Nonetheless, our study provides new evidence for the health benefits of a diet rich in live microbes, and we call on more researchers to conduct further studies on dietary live microbes.

Our study demonstrated that more intake of dietary live microbes was associated with a reduced AAC score and the risk of severe AAC among United States adults. However, more studies are still needed to validate our findings.

Publicly available datasets were analyzed in this study. This data can be found here: https://www.cdc.gov/nchs/nhanes/index.htm.

The studies involving humans were approved by the National Center for Health Statistics Ethics Review Board. The studies were conducted in accordance with the local legislation and institutional requirements. Participants provided written informed consent for participation in NHANES. The data were de-identified and all participant data were obtained from publicly available NHANES. Therefore, this study did not require further approval and followed ethical guidelines.

XH: Conceptualization, Data curation, Formal analysis, Investigation, Writing – original draft, Writing – review and editing. SJ: Writing – original draft, Writing – review and editing, Conceptualization. XZh: Investigation, Writing – review and editing. LS Investigation, Writing – review and editing. XL: Investigation, Writing – review and editing. LL: Investigation, Writing – review and editing. XZu: Investigation, Writing – review and editing. XC: Funding acquisition, Investigation, Supervision, Writing – review and editing.