Hypertension: when the microbiota rubs salt in the wound
One less pinch of salt could be enough to change the gut microbiota of hypertensive women. Their bacteria could increase the production of beneficial fatty acids, which, once in their bloodstream, could decrease their blood pressure and their arterial stiffness.
People with hypertension know that they have an increased risk of stroke, heart attack, and heart failure; and they must watch their diet and especially their salt intake. Because salt and hypertension are not a good mix. Based on studies carried out with mice, the mechanism connecting the two could be found in out gut. Moreover, since our entire diet has an impact on our microbiota, why not salt?
British researchers thus wondered whether a salt-rich diet could modulate our gut microbiota. The experiment conducted on 145 untreated hypertensive subjects seems to prove them right: a decrease in salt intake, even modest, impacted the types of bacteria living in their intestines. Their altered gut microbiota produced more short-chain fatty acids (SCFA*), which are substances that enter the bloodstream and activate vascular receptors. This is greatly beneficial to hypertensive subjects: the increase in SCFA circulating in their bloodstream seemed to be directly correlated with a decrease in their blood pressure and pulse wave velocity, which is used to measure arterial stiffness. This beneficial effect could be related to anti-inflammatory properties that are attributed to these fatty acids of bacterial origin.
Only in hypertensive women
Another finding of the study is that the underlying mechanisms appear to be different between men and women. On closer examination, the change in blood SCFAs resulting from a low-salt diet was proven only in women, and it is still unclear why. In any case, every cook should make sure not to use too much salt in their recipes, especially if someone with high blood pressure (man or woman) is eating at their table: salt consumption remains too high all around the world, and it is recommended to reduce salt intake for everyone, and especially for those with hypertension.
*SCFA: small molecules produced by colon bacteria from the fermentation process of undigested fibers in our food. They interact with our bodies and have a lot of positive impacts on our health.
Chen L, He FJ, Dong Y, Huang Y, Wand C et al. Modest Sodium Reduction Increases Circulating Short-Chain Fatty Acids in Untreated Hypertensives - A Randomized, Double-Blind, Placebo-Controlled Trial. Hypertension. 2020;76:73–79. WHO. Salt reduction. 29 April 2020. https://www.who.int/news-room/fact-sheets/detail/salt-reduction