Which site primarily performs the initial reduction of nitrate to nitrite in the body, contributing to systemic NO production?

Which site primarily performs the initial reduction of nitrate to nitrite in the body, contributing to systemic NO production?

• A. Oral cavity (mouth) via bacteria
• B. Stomach
• C. Liver
• D. Kidneys

Answer: (A)

Nitrate from the diet is taken up into saliva, and the first reduction step—nitrate to nitrite—is carried out mainly by the bacteria on the tongue and other oral surfaces. These oral bacteria possess nitrate reductase enzymes and work in the relatively oxygen-poor environment of the mouth to convert nitrate to nitrite. This nitrite then travels to the stomach and circulation, where it can be further reduced to nitric oxide under acidic or hypoxic conditions, contributing to systemic NO production. The stomach, liver, and kidneys don’t initiate this first reduction; they can participate later in nitrite-to-NO conversions, but the initial nitrate-to-nitrite step is driven by the oral microflora.

Nitrate from the diet is taken up into saliva, and the first reduction step—nitrate to nitrite—is carried out mainly by the bacteria on the tongue and other oral surfaces. These oral bacteria possess nitrate reductase enzymes and work in the relatively oxygen-poor environment of the mouth to convert nitrate to nitrite. This nitrite then travels to the stomach and circulation, where it can be further reduced to nitric oxide under acidic or hypoxic conditions, contributing to systemic NO production. The stomach, liver, and kidneys don’t initiate this first reduction; they can participate later in nitrite-to-NO conversions, but the initial nitrate-to-nitrite step is driven by the oral microflora.