- Risk factors for high blood pressure, or hypertension, include eating an unhealthy diet, lack of exercise, smoking or drinking excessive alcohol, and having obesity or overweight.
- Evidence is increasing that probiotics, whether taken as supplements or as part of a diet, might also help to lower blood pressure.
- Now, a study has identified two probiotics that reduce blood pressure in mice with hypertension, suggesting that they could have a similar effect in people.
According to the World Health Organization, high blood pressure, or hypertension, affects around 1.28 billion people over the age of 30 worldwide. Almost half of those are unaware that they have the condition as, unless blood pressure is very high, it generally causes no symptoms.
In the United States, nearly half of all adults (48.1%) have hypertension or are taking medication for it.
Hypertension increases the risk of severe health problems, including heart failure and heart attacks, aneurysm, kidney failure, stroke, amputation, and hypertensive retinopathies in the eye, which can lead to blindness.
People can reduce their risk by giving up smoking, not drinking excessive alcohol, maintaining a healthy weight, and eating a healthful diet.
Research has suggested that a healthful diet, such as the Mediterranean diet, positively influences the gut microbiome. One way that it may do this is by enhancing the number of probiotics or beneficial bacteria in the gut.
Now, a mouse study has identified two particular probiotics — Bifidobacterium and Lactobacillus — that appear to reduce blood pressure.
The study, led by researchers from the City University of Hong Kong and Inner Mongolia Agricultural University, is published in mSystems, a journal of the American Society for Microbiology.
How gut bacteria affect blood pressure
Studies have shown that an imbalance in gut bacteria is associated with hypertension in both animals and people. Bacterial metabolism can affect the immune system, causing inflammation and endothelial dysfunction, all of which affect control of blood pressure.
Some bacteria appear to have a favorable effect on blood pressure. Several studies have found that Lactobacillus spp. and Bifidobacterium spp., both of which are found in dairy products, can reduce blood pressure.
In this new study, researchers investigated the effects of two species — Bifidobacterium lactis M8 and Lactobacillus rhamnosus M9 — on mice that developed hypertension after drinking water containing 15% fructose instead of pure water.
For the 16-week trial, the researchers divided the mice into four groups. One had fructose drinking water plus saline via intragastric infusion, a second had fructose water plus B. lactis, a third had fructose water plus L. rhamnosus, and the control group had only pure water. The mice were given the probiotics via intragastric saline.
In the hypertensive mice given probiotics, blood pressure reduced significantly over the course of the study, returning to the same level as the control mice. The fructose-fed mice not treated with probiotics continued to have high blood pressure.
Dr. Cheng-Han Chen, board certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, who was not involved in the study, told Medical News Today:
“This study used a specific ‘high-fructose’ mouse model of hypertension, and showed that the probiotics B. lactis M8 and L. rhamnosus M9 led to decreased blood pressure in these mice.“
Probiotics help rebalance the gut microbiome
Not only did the probiotics reduce blood pressure, but they also appeared to change the composition of the mice’s gut microbiome.
“[The blood pressure reducing] effect appears to be due to these probiotics adjusting the balance of the gut microbiome, specifically by increasing the levels of bacteria associated with lower blood pressure (Lawsonia and Pyrolobus), and decreasing the levels of bacteria associated with higher blood pressure (Alistipes and Alloprevotella).”
— Dr. Cheng-Han Chen
Prof. Jun Li, assistant professor in bioinformatics at the City University of Hong Kong, and Prof. Zhihong Sun, microbiologist at Inner Mongolia Agricultural University, lead authors on the study, told MNT why the change in gut bacteria might have had this effect:
“We believe that the primary reason these probiotics, B. lactis M8 and L. rhamnosus M9, influenced blood pressure in mice is closely tied to the regulation of the metabolic activities of the host. The blood pressure reduction observed was linked with an increase in Lawsonia and Pyrolobus and a decrease in Alistipes and Alloprevotella.”
“Both strains regulated metabolic pathways including vascular smooth muscle contraction, serotonergic synapse, and cholinergic synapse. This study sheds light on the intricate ways through which gut microbiota impacts the overall health of the host,” they continued.
Could this work in people?
“It is far too soon to know whether this data is more broadly applicable to people. The next stage of this research will be to test and replicate these findings in humans. A significant focus will be to study the amount and duration of probiotic therapy that will demonstrate a therapeutic effect.”
— Dr. Cheng-Han Chen
Profs. Li and Sun are undertaking further research in this area:
“Based on our prior knowledge, in our ongoing research, the suggested probiotic intake [for people] is between 30-50 billion daily for a duration of three months.”
However, they caution: “It’s worth mentioning that the gut microbiota composition can vary among individuals or based on factors like age and gender. Consequently, the efficacy of probiotics can differ. Thus, determining the ideal dosage and duration requires further validation backed by clinical findings.”
Should you include probiotics in your diet?
Although this study does not provide conclusive evidence that probiotics will reduce blood pressure, the evidence for their health benefits is growing. A 2013 review of studies found that probiotics may improve intestinal health, and are useful in treating lactose intolerance, antibiotic-associated diarrhea, infectious diarrhea, and allergy.
A 2017 review found that Lactobacillus consumption could significantly reduce total blood cholesterol.
Probiotics can be taken as supplements or as part of a healthful diet.
“People get their nutrients such as probiotics through natural food rather than supplements, as food offers a more complete set of nutrients,” Dr. Chen recommended.
However, Profs. Li and Sun suggest “consuming probiotic powders or capsules that boast robust activity, ample quantity, and diverse strains,” to ensure you are getting a consistent supply. However, they caution that people who are immunocompromised should consult their doctor before taking any probiotic supplements.
Most people will benefit from a balanced, healthful diet with plenty of fresh fruits and vegetables, yogurt, cheese, and fermented foods.
“I would recommend in general that people eat a well-balanced and diverse diet of healthy foods, which includes both probiotic- and prebiotic-containing foods,” Dr. Chen advised.
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