Bacon is a type processed (cured) meat that often contains nitrates as preservatives. The problem with processed meat and nitrates is that studies have linked both to cancer [1, 2]. However, many other studies found that nitrates from food can have a positive effect on health, by for example helping make nitric oxide, a compound that keeps your blood pressure stable .
Nitrates are also present in many other foods and even in water. In fact, you get 80% of nitrates from vegetables rather than meat . So, we really don't know yet much about the role of nitrates in health.
If you want to play it safe, you can counteract any potential harm from processed, deli, and cured meats by eating antioxidant-rich food.
Keto diet foods high in antioxidants include:
green tea, black tea and coffee, cocoa powder, red wine
eggplants (most antioxidants are in the peel)
artichoke, garlic sauerkraut
broccoli, Brussels sprouts and kale
watercress and spinach
spices such as cinnamon, vanilla beans and ginger root