Are there toxic chemicals in my vegetable oil?

Cooking oil has been connected to plenty of health problems and it’s well known that too much fried food can cause obesity, heart disease and more. However, switching from one type of polyunsaturated vegetable oil to another may not be the answer to avoiding at least one problem: 4-Hydroxynonenal, or HNE. When you cook with oil containing polyunsaturated fat, you could be eating food laced with HNE, which can cause cancer, heart disease and more.


HNE and cooking oils

So what exactly is HNE? Sometimes referred to as 4-HNE, HNE is a chemical compound that forms in polyunsaturated oils when they are frequently re-heated or heated for a long time. HNE has been linked to a host of health problems. The National Institutes of Health state that HNE plays “particularly sinister roles in the metabolic syndrome and associated disease processes.”

The NIH also lists HNE as:

  • Damaging to cells in the heart and pancreas
  • Hampering the ability of cells to respond to insulin (which lowers Insulin Efficiency)
  • Harming the brain in ways that can be a factor in aging and Alzheimer’s disease
  • HNE is also linked to cancer and heart disease


Lowered insulin efficiency, the metabolic syndrome, damage to numerous parts of the body and more from HNE make avoiding it well worth the effort.


How to avoid HNE in cooking oils

Obviously, the simplest advice for avoiding HNE would be to eat only a minimal amount of fried foods. This will also help you avoid the extra calories found in many fried dishes.

At the supermarket, it won’t work if you just read the labels of cooking oils looking for HNE. The compound is created when you overuse oil or keep it heated for a prolonged period of time, meaning it isn’t actually in the oil when you buy it.

Canola, soybean, sunflower and corn oils all produce HNE.

What you can do is avoid using oils at home that contain polyunsaturated fats, as these are what eventually cause HNE to be created. You can avoid these by buying oils containing only monounstaurated fat, such olive oil. Coconut oil and butter are other choices that do not produce HNE.

If you prefer sticking to soybean, canola, et. al., you can mitigate or avoid the presence of HNE by cooking food swiftly rather than allowing it to simmer in the oil and by using new oil each time you cook.

According to a study out of the University of Minnesota, cooking oil heated or reheated to cooking temperatures over a period of 5 hours will generate HNE. Whether temperature was constant or if the oil was reheated, 5 hours was all it took.

If you’re eating out, it can be difficult to find out just what kind of cooking oil is being used, how long the current batch has been in use, etc. Your waiter or the cook should know the answer to this question, but you will likely not want to wait around long enough for a replacement batch of oil to be heated up for you. In this case, your best bet is to just avoid fried foods or risk eating HNE with your meal.