Overcooking Eggs Has An Unexpected Effect On Your Risk Of Heart Disease And Cancer

Eggs are no longer the villain when it comes to high cholesterol, according to the American Heart Association (AHA). Eggs do have a considerable amount of dietary cholesterol — 186 milligrams in a large egg — but the AHA has realized that cholesterol in foods like eggs doesn't necessarily lead to a higher risk of heart disease.

How you cook your eggs could also play a role in your health risk, according to Registered Dietitian Angel Luk. "When cholesterol is overheated, compounds called oxysterols can be created," she told Health Digest. "Some studies show that oxysterols have negative health effects, including increasing the risk of heart disease and cancer."

Dietary cholesterol can turn into oxysterols during both cooking and food storage, according to a 2022 article in the International Journal of Molecular Sciences. Your liver can also create oxysterols from dietary cholesterol, which is linked to blood cholesterol levels. High cholesterol and type 2 diabetes can cause your body to oxidize more cholesterol, leading to the creation of oxysterols. These oxysterols can speed up atherosclerosis (hardening of the arteries) and create oxidative stress that can lead to cancer.

You've probably heard how smoked or charred meat can create cancer-causing compounds, but these aren't the same as oxysterols. Oxysterols are found in cholesterol-rich foods like raw meat, but their levels increase when you cook these foods at high temperatures, store them, and reheat them. Your body doesn't necessarily absorb all of these oxysterols, but when it does, they can be harmful to your blood vessels, according to a 2017 article in Lipids in Health and Disease. Oxysterols can bind to your LDL cholesterol and lead to inflammation and increased plaque buildup in your arteries. Although oxysterols might not cause atherosclerosis, they could worsen the condition.

High cholesterol is linked to several types of cancer, but oxysterols could also influence your cancer risk, according to a 2018 article in Trends in Endocrinology and Metabolism. Researchers still don't fully understand the role of oxysterols in cancer, but they believe it might be linked to inflammation in the body. However, oxysterols might also help fight cancer by activating certain receptors that regulate cholesterol levels.

Although cooking your eggs and meats at high temperatures runs the risk of oxidizing cholesterol to form oxysterols, you still need to cook your eggs to kill any bacteria and other pathogens. The type of oil you use to cook your eggs can also increase the risk of oxidation, including plant-based oils such as olive, sunflower, and soybean oil.

Luk says eggs can be part of a healthy diet if you prepare them correctly. "I recommend making a veggie omelet with minimal oil that is heat stable, without overcooking the eggs," she said. "This way, the protein in the egg is more easily digested while the vegetables provide additional fiber and antioxidant compounds." Avocado oil is a relatively healthy oil that remains stable at higher temperatures.

If you're concerned about oxysterols, you'll also want to stay away from deep-fried foods and processed meats. Deep-fried foods require high temperatures and generate oxysterols, and oxysterols are also created in the curing or smoking process of foods like bacon and sausage. Cholesterol can also oxidize in aged cheeses when they are stored for longer periods.