Food scares – nitrite in cured meats

Fellow Tucson Citizen blogger Dr. Lauren Deville, has a post in which she warns against nitrites and nitrates in cured meats. I posted two comments, the first asking “Don’t we get most of our nitrites or nitrates from vegetables?” and the second showing that many common vegetables contain hundreds of times the nitrites/nitrates found in cured meats.  That second comment soon disappeared for some reason.

In her post, Dr. Deville, cited several epidemiological studies that found “associations” between nitrites and certain cancers. “Associations” are not evidence of causation. She also cites relative risks which tell you nothing about actual risk (see my posts linked below for a more detailed explanation). The cited studies were data-mining exercises that failed to identify possible confounding factors such as vegetable consumption and other environmental circumstances.  These studies and types of study are rebutted here. (Quotes below are from that article.)

The terms “nitrate” and “nitrite” seem to be used interchangeably. Nitrate (NO3) and nitrite (NO2) are inorganic ions that occur naturally and are part of the nitrogen cycle.

Nitrites and nitrates have been long used to preserve meat.  They block the growth of botulism, prevent spoilage and rancidity, and preserve the color.

“Nitrite is formed in especially high amounts in our mouths from bacteria. Salivary nitrite accounts for 70-97% of our total nitrite exposure.  Ingested nitrate (from foods and water) is converted to nitrite when it comes into contact with the bacteria in our saliva. About 25% of the nitrate we eat is converted to salivary nitrate, and up to 20% is converted to nitrite. Most absorbed nitrate is simply excreted in the urine within five hours.”

Nitrates occur naturally in vegetables and plants as a result of the nitrogen cycle where nitrogen is fixed by bacteria. The European Food Safety Authority (EFSA) tested the nitrate content of vegetables and reported results in their journal in June, 2008.

Cured meats today contain about 10 ppm (parts per million) nitrite.  Let’s compare that to some vegetables.

EFSA reported nitrate/nitrite content for some vegetables as follows:

arugula 4,677 ppm

basil 2,292 ppm

butterhead lettuce 2,026 ppm

beets 1,279 ppm

celery 1,103 ppm

spinach 1,066 ppm

pumpkin 874 ppm

“By definition, cured meats must include the salts, sodium nitrite or sodium nitrate, so what about those expensive ‘nitrate-free’ hotdogs and cured meats being sold to chemical-anxious consumers? They use ‘natural’ sources of the very same chemical, such as celery and beet juice and sea salt. A chemical is still the same chemical, regardless of where it comes from. NO3 = NO3. They are no more free from nitrates and nitrites than conventional hotdogs.”

“The 1981 scientific report from the National Academy of Science also concluded that there was no evidence to suggest that nitrates or nitrites cause cancer or are mutagenic. The National Toxicology Program, a division of the U.S. Department of Health and Human Services and considered the leading authority in the world on the safety of chemicals, conducted multi-year analyses at the request of the FDA. Its May 2000 and May 2001 reports “Toxicology and Carcinogenesis Studies of Sodium Nitrite,” also found “no evidence of carcinogenic activity” due to sodium nitrite. Sodium nitrite does not cause cancer in laboratory animals, these experts concluded, even when the animals are given massive doses in their water throughout their lifetimes. Also reported in the Carcinogenic Potency Database, research to date has found no link between nitrites and cancer.”

Be wary of epidemiological studies that find “associations.”  Take them with a grain of salt, or sodium nitrate.  As I said above, “associations” are not evidence.

The question for Dr. Deville is: if nitrites in meat are dangerous, why are not the nitrites/nitrates in vegetables dangerous?   Chemicals are chemicals no matter the source, and as with all chemicals, the dose makes the poison.

See also:

Statistical Games #1

Statistical Games #2 Stroke for Stroke