OK, I visited this topic awhile back (a couple of years ago) and came to the conclusion that the whole nitrate thing wasn't really an issue. That being said, I just revisited it and found that the vast majority of people looking into the topic didn't go deep enough (including Chris Kresser). As has been stated in this thread, the problem isn't really nitrates/nitrites, since they're actually beneficial to a certain extent (there are even supplemental forms of nitrate for blood pressure/erectile dysfunction/athletic performance). It's that the nitrite can convert to N-nitroso compounds that are fairly well established to be carcinogenic.
Nitrates themselves are basically inert substances but they turn into nitrites, which can then form either nitric oxide (good) or nitrosamines (bad). I'm just going to use the generic terms "nitrates" rather than specify nitrate or nitrite, and "nitrosamines" rather than specific N-nitroso compounds for the sake of convenience.
A couple of points to start off. Nitrates have been used in the curing of meats for over 200 years and the processed meat eaten today contains about 80% less nitrites than it did a few decades ago (
see here). They aren't always listed in ingredients as such; in Europe, for example they go by E numbers E 249, E 250, and E 252. There are limits to the amount of nitrates that can legally be put into food which are well below the amount needed to cause toxicity (this aside from the nitrosamine issue). The use of nitrates isn't just for appearance/taste reasons, but also to prevent the disease caused by
Clostridium botulinum; botulism.
The issue we're talking about here is nitrosamines that have formed prior to ingestion of the food. Dietary nitrites, from meat, dairy or vegetables, do convert to nitrosamines in the mouth and stomach, however the amount is negligible and not enough to cause a problem. However,
this article (from Paleomedicina; probably the most comprehensive article I found on the subject) states:
Again, this deals with conversion inside the body, not exogenous nitrosamines, but it shows how complicated the picture is. It may just be that the amount of nitrate in the diet isn't nearly as important as the state of the diet overall, as well as the general health of the microbiome. Unsurprisingly, sugar seems to be a big issue, too (from the same article):
From the Paleomedicina article, as somewhat of an aside, they say that in the curing of meats, nitrates aren't needed if the meat is dry-aged beyond three weeks. In that time, the meat dries enough to not be hospitable to the botulinum bacteria which then dies. This drying must be done outside of the fridge during this three week period. The spores and toxins remaining in the meat at this point are easily destroyed by stomach acid. During this time, however, the appearance of the product changes to become less appetizing which is why processors have moved more toward the use of nitrates. It's not directly relevant here, but it might be good to keep in mind for anyone doing home curing.
Also interesting, from the same article:
So if someone is really serious about avoiding nitrosamines, they'd better quit smoking!
One important note is that vitamin
C prevents the conversion from nitrite to nitrosamine. As I understand it, in the USA and UK,
vitamin C is mandated in the manufacturing of processed meats to prevent this conversion from taking place. I'm not 100% sure this is actually true of the US or UK, nor am I aware if this practice is done in other countries, though. This lead me to wonder if consuming vitamin C at the same time as processed meats might neutralize nitrosamine formation -
this study seems to suggest that it does. But again, that's with the creation of nitrosamines in digestion, not direct consumption of nitrosamines. It seems that using vitamin C in the curing process is required to actually stop nitrosamines from being formed in the first place.
The other issue is with cooking. Even if the curing process doesn't lead to nitrosamine formation, it may still happen when it's cooked. The higher the heat, the more likely nitrosamines are going to be created. Apparently cooking duration isn't an issue, only the amount of heat its exposed to. So cooking your bacon at a lower temperature over a longer time is better than high-heat, low-time.
This study apparently found microwaving bacon to have the least resulting nitrosamines, but I don't have access to the article so I'm not sure how it compares to other cooking methods. Keep in mind that this only really applies to foods that have added nitrates, so high heat cooking can still be used with other foods (like bacon without nitrates).
Overall, I think the whole thing is a bit of a mess and that there aren't a lot of people writing about it with solid recommendations. Because it's a relatively old practice, I'm hesitant to think that meats with some kind of added nitrate are harmful overall. As long as the diet is good and the microbiome stable (not altered by sugar and dairy consumption), any nitrates consumed should be dealt with without issue. And the addition of vitamin C, either supplemented or, if possible, used in the curing process would also minimize nitrosamines. And lastly, employing low temp cooking methods is probably a better way to go when dealing with cooking foods with added nitrates (like commercial bacon). Sourcing nitrate-free processed meats would probably be a good way to go, although they aren't easy to find.
My 2 cents...
It's usually ready products such as ham or sausages (including raw ones) rather than raw meat chunks that have nitrates or other 'badness' in it.
If it's not cured why do they need celery powder? Anyways thanks for posting this. Will check out US Wellness for my bacon needs moving forward.
