Can Oil Be Safely Reused?

Oil is a key ingredient in food preparation, particularly in Indian households and among street vendors. It plays a crucial role in cooking vegetables, pulses, and curries and is essential for frying popular items like fritters and puris. While the type and amount of oil used are significant factors for health, the practice of reusing oil also warrants attention. This raises an important question: Is it safe to reuse cooking oil?

During an insightful session titled "The Impact of Lifestyle on Health: A Poshan Perspective" at the 2024 Poshan Summit organised by OnlyMyHealth X Jagran New Media, Dr Amit Gupta, Vice President of the International Society for Medical Food and Nutrition, issued a caution on the reuse of cooking oil. He remarked, “Have you ever noticed the colour of the oil used to fry samosas at a street vendor? It often appears jet black. Yes, jet black,” emphasising that each time oil is reheated, it becomes increasingly carcinogenic.

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Carcinogenic Effect

The National Human Genome Research Institute describes carcinogen as a substance, organism, or agent capable of causing cancer. "Carcinogens may occur naturally in the environment (such as ultraviolet rays in sunlight and certain viruses) or may be generated by humans (such as automobile exhaust fumes and cigarette smoke). Most carcinogens work by interacting with a cell’s DNA to produce mutations," the research institute states.

Reusing oil can have carcinogenic effects, meaning that when vegetable oil is heated repeatedly, it undergoes chemical reactions that produce oxidised compounds that can be toxic and carcinogenic.

According to a study published in the Critical Reviews in Food Science and Nutrition, repeatedly heating cooking oils at high temperatures can generate harmful compounds, including polycyclic aromatic hydrocarbons (PAHs), which are known to be carcinogenic.

Consuming these oils or inhaling the fumes from cooking with them can increase the risk of various health problems. Studies have shown that reusing oils can damage DNA and cause mutations, leading to an increased risk of cancer, including lung, colorectal, breast, and prostate cancers.

In fact, another study published in the journal Cancer Prevention Research found that repeated heating of oils at high temperatures increased metastatic breast cancer growth.

Increased Risk Of Heart Disease

In May 2024, the Indian Council of Medical Research (ICMR) issued new guidelines warning against the repeated heating of vegetable oils. The researchers said that doing so can release harmful compounds that pose significant health risks, including an increase in the risk of cardiovascular diseases and cancer.

ICMR’s guidelines noted that repeatedly heating oils leads to polyunsaturated fatty acid (PUFA) oxidation, which in turn results in the formation of harmful compounds that elevate the risk of serious health conditions, including cancer and heart disease.

Also Read: Cancer Cases On The Rise Due To Daily Lifestyle Choices: Why Early Detection Becomes Important?

Things To Keep In Mind If You Reuse Oil

While the practice of reheating cooking oils and reusing them for frying purposes is common, Food Safety and Standards Authority of India (FSSAI) guidelines from 2018 recommended:

• Avoid repeated use of cooking oil for frying.
• At household level, oil once used for frying foods should be filtered and may be used for curry preparation in order to make it economical.
• Used cooking oil should be consumed in a day or two; it should not be stored for a longer period as the rate of deterioration is higher in used oil.
• Discard cooking oil when blue-grey smoke appears or tough foam is formed, oil becomes dark and murky, or the consistency of oil changes.
• Discard cooking oil having developed Total Polar Compounds (TPC) of more than 25%.
• In order to dispose of small quantities of used cooking oil at household level, mix the oil with an absorbent material such as sand or sawdust, a used towel or paper towel, or food scraps.
• To avoid chances of spillage and then throw it away in dustbins.

Conclusion

Reusing oils is harmful and can lead to various health concerns. Doctors and researchers warn against the repeated use of cooking oils and suggest that reheating oil can lead to an increased risk of various cancers and heart disease. If you still must reuse oil, it is important to follow proper safety guidelines, although avoiding it is the best way to protect your health.