What are the health risks of repeatedly frying samosas and jerry in oil?
Experts say, ‘Reusing oil increases the risk of heart attack, cancer and other diseases.’
Repeated heating of oil has a negative impact on health as it causes chemical changes and increases the amount of trans-fat.
It is recommended to store oil properly and use new oil.
Often, samosas, pakodas, jerry, etc. are cooked in the same oil repeatedly in chowks and markets. Some people even use the remaining oil after cooking food once in their own homes and kitchens. What happens when oil is used repeatedly in this way?
Experts say, ‘Reusing oil increases the risk of heart attack, cancer and other diseases.’
Not only at home but also in restaurants and roadside stalls, food is prepared by reheating oil. This has a negative impact on health. This can be responsible for many diseases, says senior nutritionist Bhupal Baniya.
Health effects of reusing oil
1. Chemical changes and increase in trans-fat
Repeated heating of cooking oil changes its chemical and nutritional properties. According to a study published in the Journal of Food Science and Technology (2021), repeated heating of oil increases the amount of ‘total polar compounds’, which is harmful to health.
These compounds damage the structure of the oil and increase the level of trans-fat. Bania says that trans-fat increases the risk of heart disease by increasing the amount of bad cholesterol.
According to a study published in the Journal of Nutrition 2020, reheated oil produces free radicals, which damage cells. Free radicals cause oxidative stress, which increases the risk of chronic diseases such as cancer and diabetes.
2. Cancer risk
Harvard T.H. A study by the Chan School of Public Health (2022) noted that reheated oil produces toxic substances such as aldehydes.
These substances can damage DNA, which encourages the growth of cancer cells. In particular, the oil used in fried foods is repeatedly heated, which increases the amount of these toxins, Bania said.
According to a study published in the International Journal of Cancer (2019), polycyclic aromatic hydrocarbons found in reheated oil increase the risk of cancer in the lungs, skin and other organs. This risk is especially high in fried foods in hotels and restaurants, where the oil is heated for a long time.
3. Inflammation
Reheated oil promotes inflammation. According to a study published in the American Journal of Clinical Nutrition (2021), the production of free radicals and other harmful compounds in reheated oil damages blood cells. Chronic inflammation can lead to diseases like heart disease, joint pain, atherosclerosis, and periodontitis.
4. Bacterial infections
When food particles remain in the oil, they encourage the growth of bacteria, says nutritionist Ayush Adhikari. He says, “If used oil is not stored properly, it can lead to the growth of bacteria like Clostridium botulinum, which causes botulism. This is a serious food poisoning that can cause muscle weakness, difficulty breathing, and other complications.”
5. Increase in cholesterol and acidity
According to a study published in the European Journal of Lipid Science and Technology (2023), the amount of saturated fat and oxidized lipids in repeatedly heated oil increases.
These compounds increase cholesterol levels, which harm the heart and blood vessels. In addition, the use of such oil can cause acidity, gas and digestive problems in the stomach, said Adhikari.
Ways to avoid reusing oil
Adhikari says that reusing oil can be avoided by cooking less. He says, "Do not use more oil than necessary and cook in small quantities. This reduces the chances of oil remaining."
You should try to use fresh oil every time you cook. If oil remains, he suggests storing it properly. After the used oil cools down, it should be carefully filtered to remove food particles. This prevents the growth of bacteria, said Adhikari.
"If oil is left over while cooking, it should be stored properly," says Adhikari. "The oil should be stored in a cool and dry place, away from sunlight and heat. Keeping it in the refrigerator reduces the growth of bacteria."
To avoid health problems caused by reusing oil, nutritionist Baniya suggests staying away from fast food and packet food. “These foods should be consumed less frequently as heated oil is frequently used in roadside stalls and restaurants,” says Bania.
He also says that it is important to avoid heating oil for a long time while cooking.
“When cooking, use mustard oil, olive oil or other oils with low saturated fat,” suggests Bania. “These oils are less harmful to heart health.”
Different oils have different smoke points. For example, olive oil is suitable for use at low heat, while sunflower or canola oil can be used at high heat. He also suggests paying attention to these things.
According to Bania, if there is a change in the color, smell or texture of the oil, it should be discarded. No. Such oil may contain high levels of harmful compounds, so the quality of the oil should be checked before use.
