Hi Hans,
Yes, nitrates are naturally found in many veggies. However, I did not know that storing them would increase the nitrates. Perhaps that is another reason to cook fresh veggies for each meal.
It's usually recommended for babies to avoid nitrates, however, some studies suggest that nitrates may help control heart disease in adults. (links)
Chemical in Vegetables Keep Blood Vessels Healthy( Nitrates a chemical found in vegetable...)
Nitrites, Nitrates May Cut Heart Damage, Nutrients In Vegetables And Meats May Help Protect From Heart Attack Damage - CBS News
It's always good to keep open minds & review what we've been taught with common sense.
Peace,
Dottie