The source of this article is RedNova News: http://tinyurl.com/dmoj2

Reheating Vegetable Oil Releases Toxin Linked to Parkinson's


Credit: Punchstock Research implicates cooking oils used in homes and
restaurants

HealthDay News -- High amounts of a toxin with known connections to heart
disease and neurological disorders accumulate in vegetable-based cooking
oils that are heated or reheated for hours at a time, new research shows.

The fatty acid-derived toxin, called 4-hydroxy-trans-2-nonenal (HNE), forms
in especially high amounts in polyunsaturated oils that have linoleic acid,
which include canola, corn, soybean and sunflower, researchers say. The
compound does not arise in saturated oils sourced from animal fat.

"There's a tremendous literature in biochemistry on HNE, a library of
studies going back 20 years. It's a very toxic compound," said lead
researcher A. Saari Csallany, a professor of food chemistry and nutritional
biochemistry at the University of Minnesota.

Based on the findings, American Dietetic Association spokeswoman Jeannie
Moloo said that "if a person is concerned about the health aspects of HNE,
then my recommendations would be to never heat any oil to the point of
smoking and, as far as cooking at home goes, just use the oil one time. And
avoid eating fried foods in restaurants."

Donna Garren, a regulatory affairs executive with the National Restaurant
Association, which represents more than 358,000 of the nation's eating
establishments, said there are no industry-wide rules currently in place
governing the choice and maintenance of cooking oils.

But, she added, "if there is a risk, we'd be concerned about that and want
to work with the appropriate federal agency to look at a thorough risk
assessment."

The findings were presented this week at the American Oil Chemists Society
annual meeting, in Salt Lake City.

According to Csallany, who conducted the research with graduate student
Christine Seppanen, HNE has a long pedigree as a health threat to humans.
Numerous studies have linked HNE consumption to increased risks for
cardiovascular disease, stroke, Parkinson's, Alzheimer's, Huntington's
disease, liver ailments and even cancer, she said.

Vegetable-based monounsaturated and polyunsaturated fats are inherently
unstable, especially at high temperatures, Csallany said. And "HNE arises
from linoleic acid [contained in these oils]. For example, soybean oil is
about 54 percent linoleic, canola a bit lower, corn oil a little higher,
maybe 60 percent, and sunflower oil is even higher than that," she added.


"HNE's toxicity is that it reacts very energetically with biomolecules"
once it is absorbed into the body via food, Csallany said. "It reacts with
the various kinds of amino groups -- proteins, DNA, RNA, affecting basic
cellular processes," she added.

In their previous work, Csallany and Seppanen discovered that HNE tends to
form in vegetable oils at high temperatures, accumulating steadily over a
period of up to 6.5 hours, after which point it begins to decompose.

A study they published last year in the Journal of the American Oil
Chemists' Society also found that the level of absorbed HNE in French fries
was equal to HNE concentrations in the oil the fries were cooked in, she said.

"Our next question was, 'So, what happens if somebody at home is using oil
for an hour, then lets it stand overnight for two or three days? Does it
decompose by itself? Or if it's reheated does the accumulation start adding
up again?'" Csallany said.

Their latest experiment found that "intermittent heating is just as bad as
continuous heating," Csallany said.

Based on the findings, she recommends that people avoid foods fried in
polyunsaturated vegetable oils.

"It's not so bad if you eat these foods once or twice in a while, but if
you are continuously eating them, and the oils are neglected, kept aside,
that's not so healthy," she said.

And what about fast-food restaurants, where deep fryers are kept hot and
active most of the day?

"Smaller operations tend to use soybean oil or some other vegetable oil,"
Csallany said. "At the chains -- although we haven't tested there -- they
generally use hydrogenated soybean oil. Hydrogenation doesn't get rid of
the linoleic acid, but it could make it a little less. However, it's still
there in high concentrations."

Moloo agreed that the real concern is restaurant fare. "I'm not so worried
about the home cook using a vegetable oil -- using a corn or soybean oil to
stir-fry vegetables, for example -- because most of the time it's a short,
one-time use," she said. "I'm more concerned about fried foods in
restaurants, where the oil may be used over and over."

Garren said, "It's the option of the [restaurant] operator as to what
combination of oils they use -- they might want to use a combination of
animal (protein-based) and vegetable oils, depending on palatability."

As to changing the oil, she added, "There is mention of maintenance of oils
in the [U.S. Food and Drug Administration's] Food Code, and it leaves it to
the discretion of the operator, based on the cleanliness of the oils."

She noted, however, that too-frequent changing of cooking oils can bring
its own problems.

"You have to make sure that you aren't wasting oils that are perfectly good
to use, because then you have disposal issues. We want to make sure we're
not creating another problem by arbitrarily dumping oil," she said.

But Moloo says dumping vegetable-based cooking oil after use may be a good
idea, at least in residential kitchens.

"If you deep-fry foods at home, throw out the oil after cooking rather than
saving it," she said. "And if HNE is a concern for you, then one of the
ways to eliminate it from your diet is simply not to eat these fried foods."

She also noted that not all vegetable oils are created equal.

"Oils that are high in saturated fats and monounsaturated fats are the most
stable when heated -- from a vegetable oil standpoint, those would include
peanut and olive oil," the nutritionist said.

Other polyunsaturated oils such as soybean, corn, canola or sunflower
"might better be used at room temperature, such as in salad dressings," she
added.

For her part, Csallany said she would abandon vegetable oils as a cooking
staple altogether.

"If I was frying, I'd go back to beef tallow -- it's very high in oleic
acid," which does not produce HNE, she said. "And there's new information
that shows that not all [animal-based] saturated fats are the same. Stearic
acid, for example, is found in saturated fat and it doesn't increase
cholesterol and doesn't produce HNE."

But Moloo is more leery of any switch back to animal oils.

"Anytime we're looking at eating a lot of fat in the diet it's going to
cause problems, whether it's toxic compounds that come out through the
heating process, or other components of the fat, such as high cholesterol
levels," she said.

For its part, the National Restaurant Association intends to wait for word
from the FDA, which has the power to issue guidances on these types of issues.

At this point, Garren said, "it would be fairly arbitrary for us to make a
decision -- obviously, we'd want to carefully monitor this and be of any
help we can be to the FDA in moving forward with a thorough risk assessment."

More information

University of Minnesota

National Restaurant Association

For much more on dietary fats and oils, visit the American Dietetic
Association.



Source: By E.J. Mundell

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