Effect of Probiotics on Blood Pressure : A Systematic Review and Meta-Analysis of Randomized, Controlled Trials

Khalesi S, Sun J, Buys N et al.
Hypertension. 2014 Jul 21. pii: HYPERTENSIONAHA.114.03469. [Epub ahead of print]

Background

Blood pressure (BP) can be controlled through diet and lifestyle modification. Not only are low-fat diets rich in fruits and vegetables and low in sodium suggested to lower BP [1-3], dietary constituents and supplements such as omega-3 fatty acids [4], garlic [5], and green tea [6,7] have also been found to improve BP control.
Probiotics have been studied for possible health benefits in improving immune system function [8] and preventing diarrhea [9,10]. These live microorganisms, when consumed in adequate amounts, may also improve BP through mechanisms including improving total cholesterol and LDL-c [11-13], reducing blood glucose levels and insulin resistance [14,15] and regulating the renin-angiotensin system [16,17].
Effects of probiotic consumption on BP have yielded inconclusive results. Therefore, a systematic review and meta-analysis of randomised controlled trials was conducted, on 9 eligible trials, with 543 participants. 7 studies reported a double-blind design, and one a single-blind design, and one did not report the blinding process. The probiotic source, species and dose used varied between studies, with total daily dose of probiotic consumption ranging from 10⁹ colony-forming units (CFU) to 10¹² CFU. Study duration varied from three weeks to nine weeks.

Main results

• 8 out of 9 studies reported a reduction in SBP after consuming probiotics, with a mean reduction ranging from 1.07 mmHg to 14.10 mmHg, of which 5 studies that reported a clinically significant reduction of SBP>5 mmHg.
• The meta-analysis of 9 studies revealed a significant reduction of SBP by 3.56 mmHg (95%CI: -6.46 to -0.66, P<0.01) after probiotics consumption, as compared to the control group. Statistical heterogeneity was high among studies (I²=89%, P<0.05).
• All 8 out of 9 studies that presented changes in DBP, reported a reduction after probiotics consumption (ranging from -0.9 to -8 mmHg), albeit only statistically significant in two studies.
• The meta-analysis of 8 studies yielded a significant change of -2.38 mmHg (95%CI: -3.84 to -0.93, P<0.01) in mean difference of DBP as compared with control groups (I²=78%, P<0.05).
• No meaningful relationship was found between the daily dose of probiotics consumed and reduction in SBP or DBP, although a subgroup analysis of studies with a daily dose of >10¹¹ CFU showed a significant reduction in SBP and DBP, whereas studies with a daily dose of <10¹¹CFU did not.

Conclusion

These results show that consumption of probiotics can significantly reduce SBP by 3.56 mmHg and DBP by 2.38 mmHg, which is similar to a recently reported effect of reducing salt intake by <2 g per day. This reduction is modest, but even a small reduction of BP may have relevant public health benefits and cardiovascular consequences. Therefore, probiotics may be used as a potential supplement to help prevent hypertension or improve BP control. Further studies may clarify the specific effects of different products, species and doses.

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