Kapil · Free radical biology & medicine 2013 · prospective before-after intervention study · n=19

Physiological role for nitrate-reducing oral bacteria in blood pressure control.

Cited 415 times in the scientific literature.

Level 3 - non-randomized controlled study

Non-randomized prospective before-after interventional study

PubMed 23183324 · doi:10.1016/j.freeradbiomed.2012.11.013 · record verified 2026-08-28

What was done

Nineteen healthy volunteers completed a 7-day control period followed by a 7-day treatment period with a chlorhexidine-based antiseptic mouthwash. Researchers measured blood pressure via clinic, home, and 24-hour ambulatory monitoring, alongside oral nitrate-reducing capacity and nitrite levels, after each study period.

What was found

Antiseptic mouthwash reduced oral nitrite production by 90% (p < 0.001) and plasma nitrite levels by 25% (p = 0.001) compared to control. Systolic and diastolic blood pressure increased by 2 to 3.5 mmHg, which correlated with the drop in circulating nitrite (r² = 0.56, p = 0.002). This increase occurred within 1 day of microflora disruption and remained sustained across the 7-day intervention.

Why it matters

This confirms that oral nitrate-reducing bacteria physiologically participate in generating circulating nitrite and maintaining basal blood pressure in humans.

Limits

The study evaluated a small sample of healthy individuals (n = 19) using a fixed-order before-after design without randomization or a placebo control, and only tracked effects over 7 days.

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