Excess intake of vegetable oil increases risk of cancer, heart diseases, reproductive problems —Experts

Vegetable oils are a staple in most Nigerian kitchens, but in recent times, there have been raised concerns about their health effects. Though several conflicting opinions and research findings abound among experts, the consensus remains that modern-day vegetable oils may not be as healthy as once thought and could pose a risk factor for various diseases.

Where vegetable oils originate from

According to Dr. Abiodun Adeoye, Lecturer/Consultant Cardiologist, University College Hospital (UCH), Ibadan, Oyo State, “vegetable oils are not synonymous with vegetables. Vegetable oils are oils that have been extracted from various seeds. The most common include rapeseed (canola oil), soybean, corn, sunflower, safflower, peanut, etc.”

Vegetable oils: The good

Being derived from nature, vegetable oils are indeed of benefit to the body. Mrs. Nike Shoremekun, a Lagos State health worker stated that “As a group of fat and oil, vegetable oil is good for the body when used sparingly and in the right quantity. It supplies the right oil and fat to the body.”

Dr Adeoye adds that “Fat is important for the regular function of the body. Saturated and monounsaturated fat constitutes 9 per cent with 3 per cent left for two types of fatty acids that are termed “essential” because the body can’t produce them. These are the Omega-3 and Omega-6 fatty acids. However, these should be in right proportions.”

…the bad

While vegetable oils are rich in essential fatty acids —Omega-3 and Omega-6—responsible for proper body function, sometimes a disproportionate balance in these acids could be a health concern. Dr Adeoye said, “Vegetable oils contain a very high concentration of Omega-6 fatty acids and polyunsaturated fats, which cause an imbalance in the body. Overindulgence in this type of oil predisposes one to the risk of cancer, heart diseases, reproductive problems, just to mention a few.

“While Omega-3 protects the body with its anti-inflammatory function, Omega-6 increases the risk of cancers and  heart attacks  through its pro-inflammation functions. In the blood vessels, these mutations cause inflammation that can clog arteries and may cause heart diseases. When these fats are incorporated into skin cells, their mutation causes skin cancer.”

As with every other situation, moderation is key to reaping optimum benefits. In fact, experts have stated that daily consumption of vegetable oils may be detrimental to health. “The problem is some people make vegetable oils a daily cooking item. This is harmful to the body because excess oil settles along the tubes of the heart, blocking blood supply. This can lead to high cholesterol, hypertension and obesity,” Mrs Shoremekun said.


Why vegetable oil is now a source of concern

Although vegetable oils have been around for a while, the increasing cause for concern is not unconnected to modern means of extraction and preservation. “Unlike coconut oil or olive oil that can be extracted by pressing, these new oils have to be extracted in very unnatural ways. It’s the unnatural form of these oils that raise some concerns about the effect on our health.  Also, the production processes entail the addition of chemical solvents, industrial steaming, de-waxing, bleaching, and deodorising which make the oil purely unnatural,” Dr Adeoye said.

Mrs Shoremekun identified “cuddled” oil, which has increasingly pervaded most vegetable oil stalls, as dangerous and should be avoided. She attributed this state of vegetable oil to a pitfall of poor processing. Speaking, she said, “The quality of some of these oils cannot be vouched for, even for most recommended vegetable oils. This is because the method of processing vegetable quality oil is often violated. Today, every processed oil is a potential health hazard. Some of the cooking oil displayed at most open markets are often already cuddled. This is as a result of bad processing. This type of oil is not beneficial to the body.”

She also called for more attention to be paid to the preservatives used in vegetable oil. “These chemical preservatives may not be friendly with our body. To worsen the case, the way we use the oil in cooking calls for concern. These oils are further bleached by overheating and in some case we still use and overheated leftovers,” she said.

Scientists have discovered that heating up vegetable oils led to the release of high concentrations of chemicals called aldehydes, which have been linked to illnesses, including cancer, heart disease and dementia.

Professor John Stein, Oxford University’s emeritus professor of neuroscience, said that partly as a result of corn and sunflower oils, “the human brain is changing in a way that is as serious as climate change threatens to be.” He pointed out that vegetable oils contain high Omega-6 acids which contribute to a reduction in critical Omega-3 fatty acids in the brain by replacing them.

“If you eat too much corn oil or sunflower oil, the brain is absorbing too much Omega-6, and that effectively forces out Omega-3,” said Prof Stein. “The lack of omega 3 is a powerful contributory factor to such problems as increasing mental health issues and other problems such as dyslexia.”


A better alternative

To steer clear of the risks in vegetable oil consumption, Shoremekun advises that “people should not depend on fried food. It should be avoided or reduced to the barest minimum.”

When it comes to heating oil, experts agree that heating up butter, olive oil and lard produced much lower levels of aldehydes. In fact, olive oil was shown to be especially high in monounsaturated fats and is a great source of squalene and a host of other heart-friendly nutrients.  Coconut oil was found to produce the lowest levels of the harmful chemical, aldehydes, and is far less damaged by heat than olive oil.

The palm oil point-of-view

Palm oil has always been a part of the African/Nigerian diet and is usually used as an alternative to vegetable oils. However, caution has also been called for in its use. According to researcher, David Okon Edem of the Department of Chemistry and Biochemistry, University of Uyo, Akwa Ibom State, the benefits of palm oil to health include reduction in risk of arterial thrombosis and atherosclerosis, inhibition of endogenous cholesterol biosynthesis, platelet aggregation, and reduction in blood pressure. By virtue of its B-carotene content, it also protects against vitamin A deficiency and certain forms of cancer.

He adds that  “red or refined palm oil at moderate levels in the diet of experimental animals promotes efficient utilisation of nutrients, favourable body weight gains, induction of hepatic drug metabolising enzymes, adequate hemoglobinization of red cells and improvement of immune function.”

However, these benefits are best derived when consumed in its fresh state. In his study published in the journal, Plant Foods for Human Nutrition, he stated that “Palm oil can be used in the fresh state and/or at various levels of oxidation. Oxidation is a result of processing the oil for various culinary purposes. However, a considerable amount of the commonly used palm oil is in the oxidised state, which poses potential dangers to the biochemical and physiological functions of the body. Unlike fresh palm oil, oxidized palm oil induces an adverse lipid profile, reproductive toxicity and toxicity of the kidney, lung, liver, and heart. This may be as a result of the generation of toxicants brought on by oxidation.”

The consensus is that however safe palm oil might be, it is important to take it in its natural state and not bleached or reused.c