Frying oil is often reused in homes and restaurants, is it safe? Is it related to cancer? Medical data on this in this report.

We start from a study published in 2019 in the Journal of Cancer Prevention Research, conducted on mice.

The researchers found that reheated cooking oil may lead to cell changes that can promote late-stage breast cancer growth.

Researchers from the University of Illinois at Urbana-Champaign tested what they called thermally abused frying oil, a cooking oil that has been reheated to high temperatures several times, on lab mice and found that it increases the growth of metastatic breast cancer.

Metastatic cancer is cancer that is located in another area separate from the first area where the initial cancer originated, for example, the cancer may start in the intestine and then spread to the liver.

This cancer, also known as metastases and metastases, is a cancerous growth caused by cancer cells emanating from the original tumor.

The metastases separate from the original tumor, move to other organs in the body, and then grow there and turn into secondary tumors.

Soybean oil

Scientists subjected all lab mice to a low-fat diet for a week. Some mice were then given fresh, unheated soybean oil for 16 weeks, while the rest ate "thermally mal-frying oil" instead.

The scientists chose soybean oil because restaurants usually use it for deep frying. To simulate breast cancer, they injected breast cancer cells into each mouse's trachea, which are highly aggressive and have a wide spread rate to multiple remote locations. As a result, they often appear in the lymph nodes, liver and lungs.

20 days after the cancer cells were injected, there was a marked difference in metastatic growth rate between the two groups of mice. In mice consumed "thermally masked frying oil", metastatic growth of leg tumors was four times greater than growth of tumors in mice that consumed fresh oil.

Multicyclic aromatic hydrocarbons

We turn to a research review published in 2019 in the journal Critical Reviews in Food Science and Nutrition.

The researchers found that consumption of frequently heated cooking oils was associated with a number of malignant tumors, including lung, colorectal, breast and prostate cancer.

The researchers said that reheating cooking oils frequently can generate different types of compounds, including polycyclic aromatic hydrocarbons (PAH), some of which have been reported as carcinogenic, and noted that inhaling the vapors of these oils may pose a health risk.

Why might reheated oil be bad?

Frequent reheating of cooking oil changes its composition and releases acrolein, a toxic and potentially carcinogenic chemical.

It should be noted that the topic is approached by presenting only the most prominent studies, but there are no official recommendations that reheating frying oil causes cancer.

However, the existing data indicate that it is not wise to use frying oil more than once, especially when it is used for deep frying, i.e. involving high temperatures.