A critical look at EWG’s “Dirty Dozen Guide to Food Additives” offers an opportunity for those who want to learn how to recognize activist-generated junk science and fear mongering. My blog post on Friday provided an overview for a series of posts on the topic. Today let’s start with EWG’s first allegedly bad food additive: nitrates/nitrites, which they complain are used in bacon. Yet there's no need to stop enjoying this sizzling treat, because EWG's complaints are half-baked.
EWG indicts these substances largely because they are classified as “probable carcinogens” by the International Agency on Cancer Research (IARC). The group also notes that these chemicals “may be associated with brain and thyroid cancers,” although “a causal link has not been established.” Saying that bacon “may be associated with” cancer isn’t saying much because associations do not prove cause-and-effect relationships and are often the result of a statistical accident as EWG admits.
It is true, as the IARC monograph on the topic notes, that nitrates found in these meats are converted to nitrites and sometimes form substances called "nitrosamines" during cooking at high temperatures or by stomach acid during digestion. Nitrosamines cause tumors in rodents and might cause cancer in humans exposed to high levels for relatively long durations. Yet the jury is still out on whether nitrates pose any significant risks at the levels found in food. In fact, there is much disagreement and many gray areas related to this issue, which has become a bit of a football in the debate about vegetarian/vegan diets and meat-eater diets.
Without taking sides, I must point out that some of the more helpful insights on nitrates come from advocates of meat-based diets. For example, paleo diet advocate Dr. Chris Kresser, points out the fact that bacon and meat products are not the main sources of nitrites in the human diet. Most exposure comes from fruits and vegetables, such as “cauliflower, spinach, collard greens, broccoli, beets, and root vegetables,” according to the Agency for Toxic Substances and Disease Registry (ATSDR). The anti-oxidants in these fruits and veggies appear to inhibit formation of nitrosamines. Accordingly, bacon producers add anti-oxidants to bacon along with nitrates to prevent formation of nitrosamines.
Still, EWG suggests we look for bacon that does not have nitrates as an ingredient. Yet we need to remember that nitrates act as preservatives, preventing much riskier things such as the development of botulism. And as Dr. Kaayla T. Daniel points out, bacon and other meats labeled “nitrate free” may actually have more nitrates in them than regular bacon. That’s because “nitrate-free” bacon producers often use celery salt as an alternative preservative and curing agent, which, ironically, is loaded with nitrates!
The most interesting aspect related to this issue, which EWG ignores, is research produced by Dr. Nathan S. Bryan of the University of Texas’s Institute of Molecular Medicine in Houston. His studies focus on the beneficial effects of nitrates in the human diet to fight certain diseases. This research provides some context that EWG completely leaves out.
During digestion, nitrates/nitrites produce another beneficial chemical: nitric oxide. Bryan explains: “There is a consensus that dietary nitrates are essentially inert and acquire biological activity only after reduction to nitrite. As such, nitrate serves as a source, via successive reduction, for the production of nitrite and nitric oxide as well as other metabolic products.” In 1992, scientists voted nitric oxide “Molecule of the Year,” and in 1998 several researchers earned the Nobel Prize for discovering nitric oxide’s substantial cardiovascular benefits.
Bryan notes that not all sources of nitrates are equal in the potential beneficial effects; plants are better as a source. Still his research indicates that there is little reason to panic about eating bacon with some nitrates. In a research paper, he points out: “The use of these antioxidants, along with lower nitrate and nitrite levels in processed meats, has lowered residual nitrite levels in cured meat products in the US by ≈80% since the mid-1970s.” In another paper, he and other researchers also explain that the associations found between cancer and nitrates in meat products are weak and the levels found in meat are very low indeed.
Bryan sells a nitric oxide supplement, which he discusses in an online interview along with the nitrate issue. Whether nitric oxide works in a supplement form is another question. But Bryan’s research on the benefits and the source of nitrates in the human diet is too important to ignore, and certainly makes EWG’s alarmism not only foolish, but potentially dangerous.
If EWG really cares about human health, perhaps they should be calling on people to explore foods that are a good source for potentially beneficial nitrates—such as dark leafy vegetables—rather than hyping the risks of trace levels in bacon.