By Chioma Umeha
The warning, steer clear of deep-fried and oily
foods because the extra oil is bad for the heart as well as waistlines is not
new.
But, a new study, published Wednesday in the
journal Nutrition, shows that it may be the temperature we are cooking food at
that is the real problem, not the amount of oil we are using.
“When food is heated up to a high temperature, new
compounds are created, and some of them are known to be harmful to health,”
said Raj Bhopal, professor of public health at the University of Edinburgh, who
led the research. “This is not to do with frying. … it is more to do with the
cooking process, with the temperature.”
When foods are cooked at high temperatures, they
release chemicals known as neo-formed contaminants, or NFCs. This group
includes trans-fatty acids – or trans fats – that are known to increase the
risk of heart disease.
Cooking food at extremely high temperatures
releases harmful chemicals.
Trans fats and other chemicals are increase risk
of heart disease, new research has shown.
“When the temperature is high, (trans fats) are
produced at a very high rate,” Bhopal confirmed.
The researchers believe cuisines that typically
involve cooking food in hot oils at high temperatures may explain why higher
rates of heart disease are seen in certain populations, such as among people of
South Asian descent.
The emphasis is on the temperature of your oils.
“This study shows that by heating and frying, you can change what appear to be
perfectly healthy oils and make them unhealthy,” said Michael Miller, professor
of cardiovascular medicine at the University of Maryland Medical Center, who
was not involved in the research in an online report.
By unhealthy, this means the creation of these
chemical byproducts, such as trans fats. “Heart disease can manifest if you
(then) reuse oils that have been boiled,” Miller added.
The group also looked at other byproducts of
heating oils to high temperatures, called advanced glycogen end-products. These
are also known to increase the likelihood of heart disease.
Bhopal used the example of cooking a chicken to
highlight the vast differences in how much of these byproducts are produced. When
a chicken is boiled, this cooking process releases an average of 1,000 glycogen
end-products, whereas roasting and frying produce 4,000 and 9,000,
respectively. “Different forms of cooking are leading to vastly different
results,” he said.
“The focus traditionally has looked at the foods
themselves, but not the fact you can take relatively healthy food and then make
them unhealthy,” Miller said. But he also noted that Bhopal’s research is
hypothetical at this point and needs further investigation.
The researchers have not ‘actually tested a
population,’ he said. “But this is a good background story that I agree with.”
The team now hopes to explore heart rates in
comparison to cooking methods among a population.
In the meantime, however, both Bhopal and Miller
suggest reducing the heat in the kitchen – and in your takeout box.
“It makes sense to avoid snacks that are cooked in
high-temperature oils,” said Bhopal, who himself has now switched to cooking
olive oil. “Olive oil does not heat up to a very high temperature,” he said.
Miller agreed. “Try not to boil oils … and it is
best to avoid fried foods,” he said.
But, both note that people cannot avoid these
types of food and cooking methods at all times and, as with anything, suggest
the need for moderation.
“Eating one meal is not going to do it, but it is
doing it day in, day out, on a daily basis,” Miller said.
