A Professor of Public Health Nutrition, Ignatius Onimawo, has said that it is dangerous to overheat cooking oils, warning that eating foods cooked with such oil increases the risk of heart attack, hypertension, and stroke.
Prof. Onimawo, a former Vice-Chancellor, Ambrose Alli University, Ekpoma, Edo State, said overheating vegetable oil converts it to trans fat, warning that trans fat is injurious to health.
According to him, trans fats are the worst type of fat that an individual can eat, stressing that trans fats have no known health benefits and are a major contributor to cardiovascular disease and stroke worldwide.
Speaking in an interview with PUNCH HealthWise, the nutritionist noted that when vegetable oils are overheated continuously, they get converted into trans fatty acids and cause inflammation.
The former Nutrition Society of Nigeria President explained, “When you reuse vegetable oil or any cooking oil for that matter, and you do it more than twice, the tendency is that, if you are continuously heating the oil, the fatty acid composition of the oil can be transformed into trans fatty acid.
“When you are frying, the temperature of the oil is high. Then after that the same oil, you use it again and the temperature is high.
“By the time you are using it the third or the fourth time, there is going to be a transformation of the fatty acid. They will be converted into what we call trans fatty acids.
“These trans fatty acids are responsible for cardiovascular diseases. They even cause cardiovascular diseases more than saturated fats.
“That is why we normally advise, that if you have used oil more than once or twice, it is better to discard it.”
Mayo Clinic – a medical centre focused on integrated health care, education, and research, says trans fat is considered the worst type of fat to eat.
“Unlike other dietary fats, trans fats — also called trans-fatty acids — raise “bad” cholesterol and also lowers “good” cholesterol.
“A diet laden with trans fats increases the risk of heart disease, the leading killer of adults. The more trans fats eaten, the greater the risk of heart and blood vessel disease,” the clinic noted.
Continuing, the don said, “Because the body cannot handle them, they are the ones that normally form plagues or deposits along the arteries.
“Sometimes, they form these plagues along some of the organs. So, you find out that these trans fats are more deadly than saturated fatty acids.
“Most of the saturated acids themselves lead to deposition of fats in the tissues. This leads to a build-up of pressure on the arteries and veins.
“They deposit fats inside the arteries where blood passes through and sometimes, outside the arteries. “
Prof. Onimawo said that the build of fats around and inside the blood vessels could lead to hypertension.
“They (trans fatty acids) hardened the arteries which are supposed to be flexible. So, when the plagues are there, that particular blood vessel becomes non-flexible.”
“And therefore, when it is not flexible, it cannot expand to accommodate
pressure and if that happens continuously, the blood pressure begins to increase and sometimes, that is the origin of high blood pressure.
“If this continues, you know that high blood pressure is a precursor to a lot of things that have to do with heart disease,” the nutritionist noted.
The World Health Organisation says there is evidence that heating and frying oil at high temperatures leads to an increase in trans fat concentrations.
According to the WHO, trans fat increases the risk of heart disease and death from heart disease by 28 per cent.
“On average, the level of trans fat has been found to increase by 3.67 g/100g after heating, and by 3.57 g/100g after frying.
“Approximately 540,000 deaths each year can be attributed to the intake of industrially produced trans-fatty acids.
“High trans fat intake increases the risk of death from any cause by 34 per cent, coronary heart disease deaths by 28 per cent and coronary heart disease by 21 per cent.
“This is likely due to the effect on lipid levels: trans fat increases LDL (“bad”) cholesterol levels while lowering HDL (“good”) cholesterol levels. Trans fat has no known health benefits,” WHO said.