10 December 2008

Food chemical = DNA damage

Researchers have discovered that a substance commonly found in fried and starchy food might lead to genetic mutations that could lead to cancer, at least in mouse cells.

Researchers have discovered a possible mechanism by which a substance commonly found in fried and starchy food might lead to genetic mutations that could lead to cancer, at least in mouse cells.

It's entirely unclear, however, whether these findings about the chemical, acrylamide, have any application to humans. They appear in the June 18 issue of the American Journal of the National Cancer Institute.

This type of study is used in the early stages of trying to find out whether a chemical has certain kinds of properties, says Robert Tardiff, an advisor to the Snack Food Association, a trade group. Can we tell from this study what this means in terms of human health? The answer is no.

Linked to central nervous system damage and cancer in the past
Acrylamide is considered a probable human carcinogen, a designation that was based largely on animal and laboratory trials, not human studies.

In high doses, acrylamide has caused central nervous system damage. Last year, worldwide concern escalated when unexpectedly high levels of the substance were found in foods such as french fries, potato chips, cereals and bread.

The substance has been widely used in industry. It also forms during the cooking process, as part of the reaction between amino acids and sugars when starchy foods are heated to high temperatures.

Thus far, however, acrylamide raises many more questions than it answers. While it has increased the incidence of a variety of cancers in rats and mice, no one knows the mechanism by which that happens. One theory holds that acrylamide causes potentially harmful mutations by first binding to and damaging DNA.

Possible damage to DNA tested
To test this hypothesis, researchers at City of Hope National Medical Center in California added acrylamide to mouse embryonic connective tissue cells and watched to see what would happen to a gene that they had artificially inserted.

We looked for the interaction of that chemical in the DNA molecule within the cells, says Ahmad Besaratinia, first author of the paper and a research fellow at City of Hope's Beckman Research Institute. This chemical binds to the DNA and, after replication of the DNA during cell division, leads to genetic mutations. This is considered nowadays as the initial step for cancer. Some of the binding led to mutations and some did not. The correspondence was not perfect, Besaratinia admits.

Troubling changes detected
What is potentially troubling is the changes Besaratinia and his colleagues witnessed occurred at some of the same sites as changes seen when lung cells were exposed to tobacco.

Regardless, it's far too early to know if these results hold true in rats, let alone humans.

When you look at a whole rat [or a whole human] there are balancing forces, detoxification that goes on, repair that goes on, distribution effects that can dilute out a particular chemical. The body has a lot of defense mechanisms, Tardiff says. The issue is how [do these findings] translate into whether acrylamide in cooked foods really could increase cancer risk a little bit or a lot in people. We're at the pretty early stages of trying to figure that out. - (HealthDayNews)

Read more:
Acrylamide not cancer risk
Food carcinogen levels vary


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