Nitrates & Nitrites: What’s the Beef?

Nitrates & Nitrites: What’s the Beef?

This week I was asked a question about nitrites and nitrates and their related health benefits and this question once again reminds me just how confusing my field of study (nutrition) really is. Do a quick Google search of nitrates and nitrites and you’ll find a whole spectrum of articles ranging from those that tout their health benefits to those that alarm you that these ingredients are worse than the plague.  So, I thought I would help provide some clarity to the issue, as well as bring up more questions that need to be addressed…

First let’s start with explaining what nitrates and nitrites are. Technically these are polyatomic atoms that include a nitrogen atom bonded to 2 (nitrites) or 3 (nitrates) oxygen atoms. Nitrites and nitrates can be added as nitric salts to cured meats (bacon, salami, etc.) and even other meats to preserve their red color; they are also added as a preservative to prevent the spread of microorganisms such as listeria and botulism that can cause foodborne illness. Nitrates are available to plants via the action of nitrogen-fixing bacteria in the soil and thus are found naturally occurring in fruits and vegetables, particularly foods such as beets, celery, parsley, leafy greens, and broccoli. In fact, Americans get about 80% of their daily nitrate intake from vegetables, with smaller amounts provided by surface and ground water.

It is the fate of the nitrates and nitrites that determines their effect on health. When consumed, nitrites can turn into nitrosamines, compounds that have been linked to increased risk of cancers, particularly GI cancers such as pancreatic and colon cancer. Nitrates from fruits and vegetables (& to a smaller extent whole grains), on the other hand, when consumed can turn into nitrites from the enzymatic activity in our saliva, but other nutrients in the fruits and vegetables including vitamin C prevent their conversion to nitrosamines.

To the contrary, nitrates from fruits and vegetables are more likely to convert to nitric oxide, a molecule that may have many beneficial health effects. When nitrates are reduced to nitrites and ultimately convert to the metabolite nitrox oxide there is benefits to the vasculature system supporting relaxation of blood vessels. In fact, the cardio-protective effects of dietary nitrites and nitrates include a reduction in blood pressure, reduced ischemia/reperfusion injury in heart and kidney, reduced platelet aggregation, and enhanced endothelial function. In fact one study found that dietary nitrate lowers the oxygen cost of exercise and enhances endurance by ~15% – that’s quite a benefit to our cardiovascular system during exercise!

So with all of these benefits, why do nitrites and nitrates get such a bad rap? It comes back to the alternate fate of conversion to nitrosamines (which does not happen when we consume nitrates from fruits and vegetables). We do not know for sure if it is the nitrosamine production, or perhaps other compounds in meat – particularly cured meats and red meat – that are highly associated with an increased risk for certain cancers, but indeed the relationship seems to be quite strong. There are questions as to whether it is the heme content or the high temperatures (when these meats are fried or cooked at high temps), so more research is needed to tease this out. What we currently do know is that red meat and cured meats (yes, bacon) are associated with increased risk for certain cancers, and a high intake of fruits and vegetables that provide dietary nitrates are associated with a whole host of beneficial outcomes including decreased risk for certain cancers, heart disease and metabolic disease.

This will end with a common theme in my articles (& is why nutrition can seem so confusing) – there is still more research to come. Until then, my recommendations are to limit red & cured meats to once (maybe twice) a week, and to eat 8 or more servings of fruits and vegetables a week and just avoid the nitrate/nitrite controversy altogether…

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