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It is well-established that consuming food laden with trans fats can clog the arteries, jacking up the risk of a heart attack.
But new Canadian research shows that the presence of trans fats in the blood system can also mess with the heart's rhythm, worsening the severity of a heart attack and jacking up the likelihood of death.
"It's like a double whammy," said Peter Light, a researcher at the Mazankowski Alberta Heart Institute in Edmonton and lead author of the study.
"If you eat too much trans fat or saturated fat, you may predispose yourself to a heart attack. But these bad fats don't just clog your arteries, they are stored in your heart cells, and that can affect how the heart beats.
"This can really worsen the condition of a patient suffering a heart attack."
Trans fatty acids - partially hydrogenated oils used to give texture and a longer shelf life - are found in processed foods including coffee whitener, doughnuts, microwave popcorn and frozen pizza. They're also in the oils used to make fries, fried chicken and other restaurant fare. Trans fats are responsible for between 3,000 and 5,000 deaths annually from cardiovascular disease, according to the Heart and Stroke Foundation of Canada.
The new study, published in the European Molecular Biology Journal, helps elucidate how trans fats kill. Dr. Light said the heart is essentially an electric organ, and it uses fat as an energy source. A wave of electricity passes through the heart once per second, and each time calcium is pumped in and then out again.
Dr. Light, an electrophysiologist, found that when trans fats (and to a lesser extent saturated fats) build up in the heart cells, they can affect the crucial flow of calcium.
In particular, bad fats interfere with a protein called the sodium-calcium exchanger. "Its role is to pump calcium out," Dr. Light said. "But during a heart attack, it pumps calcium in."
The greater the buildup of calcium during a heart attack, the more severe the outcome. That's because an accumulation of calcium can cause arrhythmias (irregular heartbeat) or cardiac arrest.
Dr. Light said this troubling effect on the sodium-calcium exchanger was not seen with polyunsaturated and monounsaturated fats. These so-called good fats are liquid at room temperature, such as olive oil and canola oil. Those that are solid or semi-solid, such as lard, butter, coconut oil, margarine and partially hydrogenated oils, are bad fats.
While the research was done in a lab, at a molecular level, it has some potential practical implications. For example, Dr. Light said, patients scheduled for heart surgery could be advised to cut out all trans fats for a few weeks before the operation as a way of reducing the risk of a poor outcome.
He said the research also has implications for the impact of trans fats on diabetes and hypertension, because similar mechanisms are at work.
