Gut Microbiota Tied to Hypertension in Older Adults

Improving dietary patterns may help regulate blood pressure through promoting a healthier balance of gut microbes, according to a cross-sectional study published in Nutrition & Metabolism.

Because antihypertensive drugs sometimes fail to result in optimal blood pressure control, especially among older adults, novel and complementary approaches are needed. Among these, changing the gut microbiota has shown promise.

Earlier research has indicated that gut microbiota affects blood pressure. Animal experiments found that normotensive rats became hypertensive after transplantation of cecum content from hypertensive rats. Scientists also know that the gut microbiota generates metabolites that link to hypertension. Additionally, two prospective cohort studies in the United States and Europe found that the guts of hypertensive and normotensive adults differed markedly in their gut composition of bacterial species.

Because most research linking gut microbiota to hypertension is conducted in Western countries, the results may not apply to Asian countries. Therefore, the current cross-sectional study explored the association using data from Taiwan.

The researchers recruited 20 hypertensive patients and 21 age-matched healthy controls, aged 65–80, from Cathay General Hospital in Taipei, Taiwan. To determine correlations, they collected data on blood biochemical analysis, anthropometric measurements, blood pressure, gut microbiota composition, and dietary intake from food questionnaires.

The results showed that the hypertensive patients had significantly higher waist circumference, systolic blood pressure, and BMI. They also had lower levels of Barnesiella genus and Bacteroides caccae, as well as higher levels of Bacteroides plebeius, Enterobacteriaceae family, and Acidaminococcus and Enterobacter genera. Numbers of the beneficial bacterial strain Bacteroides caccae were negatively related to the intake of unhealthy dietary constituents, including sodium, saturated fats, nut oils, and staple foods, such as noodles, bread, and steamed buns.

Several factors may underlie the relationship between lower and higher levels of specific bacterial strains and blood pressure. Possible mechanisms include the metabolites they produce, such as acetate, butyrate, and propionate, and their effects. Also, some bacteria are associated with a higher or lower incidence of maladies that could have a bearing on blood pressure, such as obesity or metabolic syndrome.

The study’s limitations included a small sample size, the lack of collection of confounders, and the recruitment of all participants from a single hospital, which could limit the generalizability of the results. Also, 75% of the hypertensive patients were taking antihypertensive drugs, which may have affected the gut microbiota composition.

Yet in the researchers’ view, the limitations were not so great that they prevented the conclusion from the findings, which is that “dietary pattern and nutrient intake may play a key role in shaping the gut microbiota and could be a target for improving blood pressure in older adults.”