High Salt Intake Damages the Intestinal Flora

A diet high in salt may promote high blood pressure and cardiovascular disease, as well as autoimmune diseases such as multiple sclerosis (MS) (1). The bacterial population in the human gut flora plays a crucial role in this, reported the journal Nature (2).

Scientists from the Max Delbrück Center for Molecular Medicine and the Charité in Berlin first examined how the intestinal microbial response of mice reacts to a high-salt diet. Although increased salt intake did not alter digestion, it did change the composition of the bacterial community in the mouse intestine. Thus, some lactic acid bacteria of the genus Lactobacillus almost completely disappeared. A return of selected species such as Lactobacillus murinus or Lactobacillus reuteri using probiotics compensated the deficit again. Some symptoms of increased salt intake, such as increased blood pressure and excessive autoimmune inflammatory response, resolved.

A test on twelve healthy men confirmed the relationship between the changes in the intestinal microbiome and the salt-sensitive diseases. Consuming six grams of additional salt over two weeks resulted in increased blood pressure. At the same time there was an increased number of TH-17 immune cells, triggers for autoimmune diseases such as MS. At the same time Lactobacillus bacteria disappeared from the intestine of those affected, if they were still there before the salty food there. Only five men were initially detected, possibly already a consequence of the western, rather saline nutritional style, according to the experts. Traditional food, which prefers fermented foods such as kefir or yoghurt, promotes the existence of lactobacilli in the intestine. However, the therapeutic effect cannot be proven so far. The scientists suspect that other salt-sensitive bacterial species in the intestine are active. If they can be identified, a way would be found to treat salt-sensitive diseases with the help of individually tailored probiotics.

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(1) Assmann – Stiftung für Prävention. Ein zu hoher Salzkonsum schwächt das Herz. Blog, available at https://www.assmann-stiftung.de/ein-zu-hoher-salzkonsum-schwaecht-das-herz-204/ (German source) with further information as well A Mente et al. Urinary sodium excretion, blood pressure, cardiovascular disease, and mortality: a community-level prospective epidemiological cohort study. The Lancet Volume 392, ISSUE 10146, P496-506, August 11, 2018, available at https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(18)31376-X/fulltext

(2) Wilck et al. Salt-responsive gut commensal modulates TH17 axis and disease. Nature volume 551, pages 585–589 (30 November 2017), available at https://www.nature.com/articles/nature24628