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Food fried In Vegetable Oil May Contain Toxic Compound

Posted Apr 22 2009 10:14am


This is an excellent article written in 2005 regarding the use of vegetable oils in cooking foods.  Please keep in mind, this is for time where the food is cooked for extended periods and oils are kept hot for hours.  There is another article written below this, that provides some clarity.


Food fried In Vegetable Oil May Contain Toxic Compound

A. Saari Csallany and Christine Seppanen

University of Minnesota researchers A. Saari Csallany, a professor of food chemistry and nutritional biochemistry, and graduate student Christine Seppanen have shown that when highly unsaturated vegetable oils are heated at frying temperature (365 F) for extended periods—or even for half an hour—a highly toxic compound, HNE (4-hydroxy-trans-2-nonenal), forms in the oil. Previously, vegetable oils such as soybean, sunflower and corn were regarded as heart-healthy because of their high levels of linoleic acid, a polyunsaturated fatty acid. HNE is incorporated into fried food in the same concentration as it forms in the heated oil. Also, Csallany and her colleagues have found three toxic HNE-related compounds (known as HHE, HOE and HDE) in heated soybean oil. They will present their work at a poster session from 9 a.m. to 2 p.m. Wednesday, May 4, at the 96th annual meeting of the American Oil Chemists Society in the Salt Lake City Convention Center.

“HNE is a well known, highly toxic compound that is easily absorbed from the diet,” said Csallany. “The toxicity arises because the compound is highly reactive with proteins, nucleic acids--DNA and RNA--and other biomolecules. HNE is formed from the oxidation of linoleic acid, and reports have related it to several diseases, including atherosclerosis, stroke, Parkinson’s, Alzheimer’s, Huntington’s and liver diseases.”

Csallany’s work underscores the risk of repeated heating, or reusing, highly unsaturated oils for frying because HNE accumulates with each heating cycle. In future studies, Csallany and her colleagues plan to determine how long polyunsaturated oil must be heated at lower temperatures in order to form HNE and its related compounds. The study was funded by the University of Minnesota.

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HD Lighthouse Contributing Editor's Comment:

Although Huntington's Disease is mentioned in the press release below, I can find no research which reports that HNE is elevated in the brains of HD patients. There is research showing that elevation of this neurotoxin occurs in the brain tissue of Alzheimer's patients and HIV patients experiencing progressive dementia, however. HNE even appears to associated with the formation of neurofibrillary tangles in Alzheimer's.

There would certainly appear to be a connection with HD. We know that lipid peroxidation results from free radical-mediated injury to brain. Free radical damage and the resulting oxidative stress in neurons occurs in Huntington's Disease and lipid peroxidation is also found. 4-Hydroxy-trans-2-nonenal (HNE) is a product of lipid peroxidation.

Given the findings in the press release below, it would seem best to avoid fried food in restaurants where the vegetable oil would be used for a considerable period of time. At home use other ways of cooking or if you want to use vegetable oil to crisp the food, use it at the end of the cooking process. This seems like good advice for all of us since we are all aging and good advice for people with Huntington's Disease in particular since their neurons are particularly vulnerable to oxidative stress.
--Marsha L. Miller, Ph.D.
Posted to the HDL: 29 May 2005

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