Probiotic EffectProbiotic Effect on Dietary Nitrate to Plasma Nitrite Production ( OPEDNPN )

Nitric Oxide (NO) is an important molecule that is produced naturally in the body and that helps maintain healthy blood flow. Low availability of NO contributes to many diseases while administration of NO is therapeutic.

In addition to being made naturally in the body, NO can be obtained through the diet via the Nitrate-Nitrite-NO cycle. Nitrate, which is abundant in green leafy vegetables and beetroot juice, is partially converted to nitrite by oral bacteria. The nitrate and nitrite are taken up into the blood and nitrite is converted into NO. Remaining nitrate in the blood is taken back up into the mouth by salivary glands and the cycle continues. Emerging studies suggest that the Nitrate-Nitrite-NO cycle may contribute to cardiovascular health. In addition, there have been many studies where dietary nitrate is given to increase NO and treat various conditions.

The current study rests on the premise that the quality of the oral microbiome plays a major role in the Nitrate-Nitrite-NO cycle and hence cardiovascular health and the efficacy of dietary nitrate interventions. Investigators have begun to identify oral bacterial species that are effective nitrite producers as well as though that are nitrite depleters (those that interfere with nitrite production from nitrate).

In laboratory experiments, certain bacterial species have been shown to block nitrate to nitrite conversion by other oral bacteria. These nitrite depleting species are found in a commercially available oral probiotic designed to improve oral health. The purpose of this study is to examine if use of the probiotic negatively affects the Nitrate-Nitrite-NO cycle. Nitrate to Nitrite conversion will be assessed by measuring plasma levels of nitrite before and after consumption of nitrate-rich beetroot juice. Dietary nitrate to plasma nitrite conversion will assessed at baseline and after one week of consumption of the probiotic or a placebo (follow-up). The primary hypothesis of this study is that participants that consume the probiotic will have lower nitrate to nitrite conversion at follow-up compared to baseline and that there will be no significant change in nitrate to nitrite conversion between baseline and follow-up for participants who consume the placebo.

While this study does not aim to treat any specific disease, it is intended to elucidate a basic physiological function that may be relevant to cardiovascular health and certain NO-based therapeutics.