Assessing the Benefit-Risk Ratio of Nitrates

Many readers may have come across a recent report linking the consumption of processed meats (sausage, bacon cold cuts, etc.) to the incidence of pancreatic cancer. Intriguingly, the higher risk seemed to only apply to men and not women. The explanation for this remains obscure, but may reflect other dietary habits more common to men or other factors, such as increased alcohol consumption or smoking. But this is only a speculation.

The presumptive mechanism of cancer causation seems to revolve around the presence of nitrates in these cured meats. Nitrates are added to meats as preservatives. Preservatives function to inhibit bacterial growth responsible for food spoilage. Nitrates under the acid conditions in the stomach, are converted to nitrites. And it is these nitrites, primarily in the form of nitrosamines, which may be the culprits.

When we exam these findings several issues must be considered. First, however nefarious the consuming public may think the meat packing industry, I for one am fully convinced that these companies do not add nitrates to cause cancer. Quite the contrary. The most dangerous organisms found in foodstuffs, through spoilage and lethal food toxins, are the anaerobic organisms. The most frightening of all is clostridium botulinum, which produces the fatal condition known as botulism. Nitrates converted to nitrites are potent inhibitors of clostridia.

In the grand scheme of things, it is highly likely, in fact certain, that many, many more people have been saved from nitrites in food than would ever die from pancreatic cancer. These risk-benefit ratios are the subjects that keep epidemiologists up at night.

Nitrates in food are not the only possible man-made exposures that we encounter on a daily basis. Take for example chlorinated water. The “chlorine” in water is, for all intents and purposes, bleach. That’s right every time you drink tap water you are being exposed to tiny quantities of bleach. It is probably unnecessary for me to explain to the average reader, the risks and hazards of common household bleach, which is a solution of hypochlorite. And, however toxic that bottle under your sink may seem, remember that is only a 5 percent solution.

Another example is fluoride. While the benefits of fluoridation of water are numerous, including bone density and improved hardness of the enamel of teeth, demonstrably reducing tooth decay, fluorine itself is not, at least theoretically, free of risk. We know that sodium fluoride is an inhibitor of phosphodiesterase, an enzyme responsible for regulating cyclic AMP and cyclic GMP levels in the cell. These protein kinase A signals events may be tonically affected by changing levels of fluoride in the cell, to what end it is hard to say.

Like chlorination or fluoridation of water, nitrates in food represent risks that we as a society have accepted, based upon what we deem as acceptable benefit-risk ratios.

It is possible, that the increased incidence of food-borne illness and enteric infections, increased dental caries associated with the elimination of all these risks, may far exceed the hazards associated with these exposures.

The human species evolved over millennia in an environment exploding with free radical activity, fortunately we have developed defenses, superoxide dismutase, glutathione, peroxidase, catalase, etc., that counteract the toxic effects of these chemical compounds. Whether the man-made exposure substantively changed the balance will be a topic of discussion for years to come.