nitrate danger in food

nitrate danger in food

QUESTION: I have several relatives who have had colon cancer, and one of the things I am doing is staying away from foods that use nitrite preservatives, because they can form cancer-causing nitrosamines. I now read that spinach and many of the other vegetables I eat contain nitrates and that these can convert to nitrites. How dangerous are the nitrates in foods, and are these things I should also be seeking to limit?

– B.G., Las Vegas

ANSWER: Nitrates are compounds that are naturally present in many types of foods, including vegetables and fruits. Nitrites are food additives used in cured meat products to decrease the risk of botulism. Nitrosamines are carcinogenic compounds that can form when a nitrite combines with an amine. (Amines are released when the amino-acid building blocks of protein are metabolized.)

Before a nitrate can become a nitrosamine, it must first be reduced into a nitrite, and it then has to be alongside an amine in an environment that encourages their combination. The conversion of nitrate to nitrite is usually handled by bacteria, and while there are bacteria in our saliva, they convert only a small amount of the nitrate we consume. The process is inhibited in an acid environment, so if there is vitamin C, as is often the case with fruits and vegetables, the conversion proceeds even more slowly.

Nitrates tend to be absorbed after they leave the stomach. There are bacteria in the large intestine, but by that point, there is a negligible risk of any nitrate straggler finding and sidling up to an amine and turning into a nitrosamine.

Contrast all this with nitrate-preserved meat products, in which all the players (the nitrite and the amine from the meat protein) are there in the same package. There is no guarantee that nitrosamine will form – and nitrites are certainly preferable to the risk of botulism – but by comparison, the natural nitrates in fruits and vegetables represent a healthful walk in the park.

Are canned beans such as red, navy, pinto, etc., as nutritious as dry beans? It is more expensive but less work to open canned beans rather than cooking them from the dry state.

– C.W., Baton Rouge, La.

Canned beans are just as nutritious as dry beans. Many commercial products have added salt, but giving the beans a fresh-water rinse or two will remove a lot of that sodium. There are also low-and no-salt varieties of canned beans available.

Not only was your advice good (in a recent column), but the diction was as well. You described food as “healthful.” Yes! Obviously, the foods we eat should be “healthy” as opposed to diseased, but that’s not usually what is meant by the encouragement to eat “healthy” food. It’s nice to see that someone else knows the difference. Thanks.

– M.S., San Diego

Healthful foods, yes! Once picked and cooked, foods would no longer be considered healthy. The distinction is a minor thing, but most continue to get this one wrong. Thanks for noticing.

Ed Blonz, Ph.D., is a nutritional scientist based in Northern California. General-interest questions about nutrition can be mailed to: Ed Blonz, Focus on Nutrition, P.O. Box 120191, San Diego, CA 92112-0191, or sent via e-mail to .



~ by sunil khemaney on April 23, 2009.

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