Health officials have long known that too much nitrate — a common, naturally occurring chemical compound — can cause health problems for infants and pregnant women. But some have tended to discount suggestions that nitrates may also create problems for adults. New research by an MU professor of chemistry suggests this is shortsighted. In December, Richard Loeppky and his research team announced they had isolated a new, nitrate-related compound — a "nitrolic acid" — that appears to adversely affect the genetic make-up of the stomach. "While we don't know much about this newly-discovered compound, the evidence suggests that it can alter or damage DNA," Loeppky says.
Nitrate contamination is common in rural areas where nitrate-rich chemical fertilizers often leach into well water. Infants are at particularly high risk because of a quirk in baby physiology: When less than six months old their bellies contain a bacterium that converts nitrates into nitrite, a chemical that can inhibit the blood's ability to carry oxygen. A lack of oxygenated blood can, in turn, lead to methemoglobinemia, or "blue baby syndrome," a condition in which infants become so oxygen-starved that their mouth, hands, and feet turn blue.
Because older children and adults lack the offending bacteria, they were thought immune to nitrate's ill effects. Not so, says Loeppky. When adults ingest nitrate-laden food or water, he explains, the chemical passes into the blood stream via the normal digestive processes. Once in the blood, some of it ends up in saliva glands where, unfortunately, it meets a bacterium similar to the one in babies' bellies. The nitrate is thus transformed into nitrite and, when swallowed, returned to the stomach. There the nitrite combines with dietary amino acids to form the newly identified nitrolic acids.
"The stomach is an ideal reactor for the kinds of chemistry that we are talking about," says Loeppky, whose study was published in Chemical and Engineering News and presented at the American Chemical Society meeting last fall. "Other researchers have suspected that amino acids played a role in forming these compounds, but until we made this discovery, no one had much of an idea how this happened."
Nitrolic acid in adults does not appear to affect oxygen uptake, but Loeppky suspects it could have other deleterious effects, among them cancer development.
Nitrates in municipal drinking water supplies are carefully regulated to ensure they remain at safe levels. Nevertheless, the Centers for Disease Control and Prevention in Atlanta estimates that most adults still consume about 20-25 milligrams of nitrate-nitrogen per day. Loeppky fears this may be too much: "Reduction of nitrate in consumable water is most important," he says. "Next, we should try to reduce nitrate in vegetables through reduction of over-fertilization. Finally we should watch our consumption of cured meats."
So we should give up frankfurters? There is no need to get obsessive about it, Loeppky says. After all, he adds, "most people don't eat hot dogs every day."