Nitrates In Pork
Often lost in the debate about nitrates in pork is the inescapable fact that nitrates (technically nitrite) is the thing that makes ham taste like ham. If you’ve ever had roasted pork, you’ll know that it’s good, but it’s not ham. You only get that specific flavor with nitrite. This has been known foe milennia. Consider:
So nitrate and nitrite have been used in the curing of meat for a very long time indeed. For both color AND flavor. Where does nitrate come from and why is it so prevalent in salt deposits? Do you remember the nitrogen cycle from biology class?
Nitrogen is fixed by nitrogen fixing bacteria in the nodules on the roots of legumes. Other bacteria convert the fixed nitrogen into Ammonium, then nitrite, then nitrate where it is taken up by plant roots. Without nitrates, plants couldn’t make protein. Without plant proteins, cows, pigs, chickens and humans couldn’t exist. So nitrate is very important.
It’s a relatively common mineral since the atmosphere is 78% Nitrogen and soils everywhere contain Nitrogen fixing and Nitrifying bacteria. Some places it builds up as a mineral. These nitrate deposits have been mined since pre-Roman times as a meat cure.
It is technically the nitrite that does the curing, binding with the iron in hemoglobin to form a compound called nitrosohaemoglobin that breaks down to nitrosohaemochromogen during cooking. It is the nitrosohaemochromogen that gives ham it’s distinctive pink color and nitrosohaemoglobin that gives uncured meats like prosciutto their distinctive red coloration.
Those old mineral deposits might have been 95% nitrate and 5% nitrite, so to add the 50 ppm (parts per million, that’s 0.005%) of nitrite, you would have had to add an additional 1000ppm of nitrate. Look at this meat survey done in 1937. The huge amount of nitrate is just along for the ride:
Probably many of you have seen nice pink “uncured, nitrate free” natural ham, bacon and hot dogs. I’ve even played my role in that expensive ruse. Here’s how it works: you grow a crop of hydroponic celery. You put a bunch of nitrate in the water. They absorb it because that’s what plants do. Then you juice them, add an enzyme that converts the nitrate into nitrite and powder the juice. The “celery juice powder” has plenty of nitrite to cure the meat even if only 0.4% of it by weight is added to the recipe. And now somehow the meat is nitrite free! Cool trick, huh? Of course, it’s a lie. So there’s that.
In my opinion, it’s better to do the honest thing. If you want the best flavor, use the exact amount of sodium nitrite needed. You’ll get great flavor and far less nitrate in your meat than the Romans would’ve been eating.
Who’s Afraid of A Little Nitrite?
The reason people are concerned about nitrates in meat is that certain studies have shown a small but statistically significant correlation between consumption of cured meats (typically pork), but not red meat or chicken, and certain cancers. For instance, those who eat a lot of processed meat are 20% more likely to get colon cancer. This raises your lifetime real risk of getting colon cancer from around 5% to around 6% (6 is 20% more than 5). Anyone who took eighth grade science should now be thinking “but correlation doesn’t necessarily imply causation, does it?” If you were thinking that, give yourself a gold star.
The problem is that there is no clear mechanism by which cured meat should specifically cause cancer. This review article is actually very good and breaks down all of the suggested mechanisms by which eating processed meats could potentially cause colon cancer, including: high fat intake, heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) formed during the cooking of the meat, nitrosamines from cooking the meat or heme groups (iron).
In a nutshell:
- The evidence for fat is not convincing.
- Cooked chicken forms just as much HCAs and PAHs as cured meats, but chicken isn’t correlated with colon cancer.
- In the case on nitrosamines, even though consumption of cooked processed and red meats greatly increased the amounts found in feces, “Animal studies showed that processed meat intake leads to fecal excretion of NOCs, but without any evidence of initiation or promotion of ACF.” ACF are “aberrant crypt foci”, the early stages of cancerous growth in the colon.
The high dietary heme iron argument requires more discussion. Iron can promote “peroxydation of fat in foods and in the gut, and the lipoperoxides would promote colorectal cancer”. This argument falls down on the surface of it because beef has more heme iron than pork but pork is the one with the stronger cancer correlation. But wait! The fats in beef are largely saturated and not prone to oxidation. The relatively high amount of PUFA in most pork would be highly prone to oxidation and it is delivered with heme iron, a potential pro-oxidant. Essentially, the heme iron theory may only be an issue in the presence of significant PUFA. This feels like an argument in favor of Low PUFA pork.
The Real Issue?
All of that may simply be prelude to the REAL answer cured meats are associated with colorectal cancer. I present this quote from the paper:
Individuals who eat more processed meat than average often tend (i) to eat less fruits and vegetables, (ii) to drink more alcoholic beverages, (iii) to smoke more tobacco and (iv) to eat more calories, more fat and be more obese and less active, than those who do not eat processed meat
I’m going to paraphrase that quote, “people who eat the most processed meat are the ones most likely to be eating the Standard American Diet (SAD) and therefore are most likely to have metabolic syndrome.” The high fat consumption is probably from the hash browns consumed with the sausage McMuffin. My personal belief is that the reason cured meats correlate with colon cancer is because of the lifestyle of the person who typically consumes cured meats.
The curing of meat with nitrite is an age old tradition that improves both the visual appeal BUT EVEN MORE SO the flavor of cured meats such as ham, bacon and hot dogs. I see no huge health risk from a small amount of nitrosohaemochromogen, especially in the context of Low PUFA pork. Nor am I interested in continuing the ruse of “Uncured, nitrate free pork” that is cured with celery powder. If you buy a share of low PUFA pork, the specific products that need it for flavor – ham, bacon, hot dogs – will have just enough nitrite to cure them and no more.
- Binkerd EF, Kolari OE. The history and use of nitrate and nitrite in the curing of meat. Food and Cosmetics Toxicology. Published online January 1975:655-661. doi:10.1016/0015-6264(75)90157-1
- Santarelli R, Pierre F, Corpet D. Processed Meat and Colorectal Cancer: A Review of Epidemiologic and Experimental Evidence. Nutrition & Cancer. Published online March 2008:131-144. doi:10.1080/01635580701684872