High blood pressure (hypertension) is a major risk factor for cardiovascular disease. One important contributing factor to high blood pressure is reduced availability of nitric oxide (NO). Therefore, NO is an important molecule in maintaining healthy blood vessel function. Dietary nitrate, found in leafy greens, can serve as an alternative source of nitric oxide in the body. After ingestion, nitrate is converted to nitrite by bacteria residing in the oral cavity. Nitrite can subsequently be converted to NO when swallowed. Therefore, this nitrate-nitrite-nitric oxide pathway is dependent on oral bacteria. This study aims to assess whether rinsing the mouth with a nitrate-rich mouth rinse influences blood pressure in healthy adults. Also, concentrations of nitrate and nitrite in plasma and saliva will be measured following the nitrate-mouth rinse exposure.
This study investigates the potential acute blood pressure lowering effects of a simple nitrate-rich mouth rinse and drink, while also monitoring their effects on oral nitrite production capacity (NPC), plasma and salivary nitrate and nitrite levels, oral pH levels and the oral microbiology. The study is a short-term, double-blind, randomized, placebo-controlled, crossover trial. Participants will receive interventions and donate samples at four separate sessions. At session (i), baseline measurements are taken prior to intervention, and samples are subsequently taken (as described under outcome measures). At session (i) and (ii), the participants will rinse the oral cavity with a nitrate-rich fluid (or placebo). Similarly for sessions (iii) and (iv), the participants will drink the same fluid (or placebo). When donating samples, the participants will be in fasting condition. In total there will be four sessions per participant with wash-out periods in-between. To elucidate the short-term effects of the above-described interventions, sampling will be performed in the clinic at multiple time points during the first 2 hours after each intervention, as well as at 24 hours. Participants will also monitor their blood pressure at home at four different time points for all four interventions. No sampling or measurements will be performed during night-time. For both the intervention and the placebo, potassium (K) salts are used (KNO3 and KCl). For chairside measurement of NPC in oral samples, the rapid Griess assay (RGA) will be used. Blood pressure will be measured at the study facilities as clinic blood pressure and orthostatic blood pressure (CBP and OBP, respectively) using a clinically validated blood pressure monitor. The same device will be used by the participants for home blood pressure measurements (HBP). Saliva pH will be measured using pH-sticks or a pH-meter. Plasma and saliva nitrate- and nitrite levels are analyzed using commercial laboratory kits. Salivary secretion rate (SCR) is recorded during saliva donation, and measured as volume per unit time. Microbiological effects will be analyzed with appropriate methods in the laboratory.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
20
The oral cavity is rinsed with nitrate from mouth rinse, rather than ingested.
Nitrate is ingested, rather than rinsed and spit out
This mouth rinse is devoid of nitrates
This drink is devoid of nitrates
Odontologen, University of Gothenburg
Gothenburg, Västra Götaland County, Sweden
Blood pressure before and at regular intervals within the 24 hours after nitrate exposure.
Blood pressure will be measured before and with regular intervals after nitrate exposure. The measurements will be registered as systolic and diastolic measurements from clinic blood pressure and home blood pressure.
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure.
Oral nitrite production before and at regular intervals within the 24 hours after nitrate exposure.
The nitrite production is measured using the rapid Griess assay (RGA) - a chairside semi-quantitative nitrite concentration estimation tool for use in several different oral samples. The RGA provides nitrite estimation on a grading scale of 0-5 with nitrite concentrations intervals.
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure
Plasma and salivary nitrate and nitrite levels before and after nitrate exposure.
Blood samples are drawn from venous blood before and 1 hour after nitrate exposure, and plasma is separated. Saliva nitrate/nitrite is extracted from saliva samples donated before and 1 hour after nitrate exposure. Both are analyzed using commercial laboratory kits.
Time frame: Baseline (prior to nitrate exposure) and 1 hour after nitrate exposure.
Salivary pH levels at regular intervals.
Salivary pH will be measured using a pH-stick at regular intervals before and after nitrate exposure.
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure.
Orthostatic blood pressure before and at regular intervals within the 24 hours after nitrate exposure.
Orthostatic blood pressure will be measured at regular intervals before and after nitrate exposure and reported as systolic and diastolic blood pressure values in mmHg.
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure.
Salivary secretion rate before and after nitrate exposure.
Salivary secretion rate will be registered as volume per unit time when donating saliva before and after nitrate exposure with regular intervals.
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure.
Relative abundance in cultivable oral microbial composition after nitrate exposure
Microbial samples from multiple oral sites will be collected before and after nitrate exposure. Oral microbial composition will be analyzed and reported as the relative abundance (%).
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure.
Absolute abundance in cultivable oral microbial composition after nitrate exposure
Microbial samples from multiple oral sites will be collected before and after nitrate exposure. Cultivable oral microbial composition will be analyzed and reported as absolute abundance and expressed as colony-forming units per milliliter (CFU/mL).
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure.
PCR detection of specific oral bacterial after nitrate exposure
Microbial samples from multiple oral sites will be collected before and after nitrate exposure. Quantitative PCR analysis will be performed for selected oral bacterial species and reported as bacterial counts or copy numbers.
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure.
Oral microbial metabolite concentrations after nitrate exposure
Microbial samples from multiple oral sites will be collected before and after nitrate exposure. Oral microbial metabolites will be analyzed and reported as metabolite concentration values.
Time frame: Baseline (prior to nitrate exposure) and during the 24 hours after nitrate exposure.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.