Lately I do a lot of pickling with vinegar/salt/sugar. I'm now addicted to pickled daikon. If I could only find a container capable of restraining the smell...
People who make 'organic' sausages, for example, add celery as a 'preservative' so that they don't have to use the 'chemical' nitrite - except, the way it 'preserves' is that the nitrate in the celery is converted to nitrite during fermentation, but much less controlled than just measuring out nitrite in the first place, so those 'organic' or 'artisanal' sausages often have higher nitrite content than 'normal' sausages.
A quick google shows that this might happen for some vegetables too (e.g. https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1745-4549....) but I can't tell if the same would hold for all fermented food.