Reducing sodium levels in people with high blood pressure increases levels of short-chain fatty acids and reduces blood pressure.
Researchers have discovered that reducing salt levels in the diet of people with hypertension, increased circulating short-chain fatty acids in their blood as well as decreasing their blood pressure. The study authors suggest this could indicate a causal link between short-chain fatty acid levels and blood pressure. This finding could open up new avenues of research into blood pressure reduction. The study is published in the journal Hypertension.
Short-chain fatty acid levels reflect microbial activity in the intestines as they are produced by the breakdown of fibre by microbes and absorbed across the intestinal lining. They provide fuel for cells in the intestinal epithelium but they also seem to have other effects on our health, including influencing our immune system, our weight gain and blood pressure. Some studies suggest that faecal short-chain fatty acid levels are related to blood pressure and metabolic syndrome risk factors (Teixeira et al., and de la Cuesta-Zuluaga et al.). Studies with individual short-chain fatty acids suggested they could lower blood pressure (Onyszkiewicz, M. et al. Marques et al.).
A study in an animal model of hypertension published in 2018 by Bier et al. suggested that short-chain fatty acid levels and the composition of the microbiota in the gut could be altered by increasing salt in the diet. This study from Haidong Zhu’s group at Augusta University shows for the 1st time, similar effects in human subjects and together they suggest that the mechanism by which salt affects blood pressure may involve the microbiota.
The 145 study participants, 34% of whom were womenn had high blood pressure at the start of the study. They all consumed a diet that was low in sodium containing around 2.3 g daily initially for 2 weeks and then one group consumed NaCl supplements while the other consumed placebos for 6 weeks. Next, the participants swapped groups for another 6 weeks. The researchers measured levels of 8 short-chain fatty acids in participants’ blood at the beginning of the study and after each 6 week period
While the participants were on the low sodium diet, they exhibited significantly higher amounts of 5 of the short-chain fatty acids in their blood than when they consumed high levels of salt. When the researchers analysed the results by the participants’ gender they found the effect was only significant in women.
The American Heart Association recommends that people consume less than 2.3 g of sodium daily to avoid hypertension. This is the amount found in a teaspoonful of salt,
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Reference
Modest sodium reduction increases circulating short-chain fatty acids in untreated hypertensives: a randomized, double-blind, placebo-controlled trial. Li Chen, Feng J. He, Yanbin Dong, Ying Huang, Changqiong Wang, Gregory A. Harshfield, Haidong Zhu. Hypertension. 2020; 76:73–79.
https://doi.org/10.1161/HYPERTENSIONAHA.1. 20.14800