Of all additives and preservatives, one of the most prominent found in our food are the nitrates. They are used to colour and preserve foods, especially meats. It has been found that these destabilize the body’s oxygen supply, with potentially fatal results if eaten in sufficient quantities.
Blackouts are uncommon but can occur because of a drop in blood pressure due to nitrate ingestion. As usual, the orthodox world has set a safety level of 200ppm in any food and thereby suggest that taking in 190ppm is safe but 201 ppm is not. There is, as always, a grey area and some people are more sensitive than others. Beware and avoid any foods containing nitrates.