So, if both nitrates and nitrites are present in vegetables and processed meats, albeit at different levels, why are some thought to be beneficial for health and others potentially damaging?

The nitrate-nitrite-NO pathway is emerging as an important ... will include new candidate enzymes that may be specific for different tissues and/or at different pH or oxygen gradients.

In humans, dietary nitrate (mostly from green leafy vegetables) is converted to nitrite in saliva, and to nitric oxide (NO) in the acidic stomach. Petersson and colleagues hypothesized that ...

This is a differential medium. It is used to determine if an organism is capable of reducing nitrate (NO 3-) to nitrite (NO 2-) or other nitrogenous compounds via the action of the enzyme nitratase ...