- 1. What is nitrate?
Nitrates are nitrogen compounds which occur naturally in soil, but which can also be spread through fertilization. Plants utilize the nitrogen contained in nitrates for their own metabolism and to produce protein. Nitrate is extracted from the soil by the roots and distributed throughout the plant where it is converted into high-energy protein compounds by means of photosynthesis. Excess quantities of nitrate are stored, with food plants having different nitrate storage capacities. Nitrate from soil can also be washed into groundwater through rainfall, which means that it can ultimately be found in drinking water too. The nitrate levels in ground and drinking water can be considerable, depending on the predominant form of land use.
- 2. What is nitrite?
Nitrite is an interim product in the supply of the plant with nitrogen. As plants cover their nitrogen requirements through nitrate, plant-based foods - especially various vegetable varieties - can contain comparatively high quantities of nitrate. In vegetables containing nitrate, microbiological or enzymatic effects can cause conversion of the nitrate into nitrite. This can happen as a result of improper storage, incorrect transport and/or non-observance of the standard rules of hygiene.
- 3. What are the sources of nitrates/nitrites?
Because plants cover their nitrogen requirements through nitrate, plant-based foods - especially various vegetable varieties - can contain high nitrate levels. As a basic principle, the nitrate accumulation in the plant depends on the amounts of nitrogen contained in the soil. Storage capacities vary depending on the type and part of the plant. Vegetables such as rocket and other leaf lettuces, spinach, kohlrabi, beetroot, as well as red and white radish store a lot of nitrate. As nitrate accumulates particularly in the segments of the plant that conduct water, it is to be found in higher concentrations in the stem, leaf veins and outer green leaves.