Key Update

Many assume oil is safe as long as it looks clear, but repeated heating triggers chemical changes that reduce its quality and safety. High temperatures, oxygen, moisture, and leftover food particles speed up breakdown. The oil becomes darker, thicker, and loses its smoke point, causing it to burn faster. Even when it looks normal, it may already be degraded at a molecular level.

Key Changes in Reused Oil

• Free fatty acids increase as triglycerides break down.
• Antioxidants are depleted, making the oil oxidise quickly.
• Reactive aldehydes and harmful by-products form.
• Polymerisation thickens the oil and alters frying performance.
• Unsaturated fats decline, increasing trans-fat formation.
• Food particles accelerate chemical deterioration.

Health Risks You May Not Notice

Scientific studies show reheated oils generate aldehydes, polymeric compounds, and PAHs—substances linked to DNA damage and higher oxidative stress. Long-term intake of foods fried in degraded oil, along with inhaling fumes during frying, is associated with increased risk of colon, breast, lung, and prostate cancers.

How It Affects Your Body

• DNA damage and oxidative stress increase.
• Liver strain rises due to oxidised fats.
• LDL cholesterol and triglycerides may be elevated.
• The risk of fatty liver and heart disease increases.
• Frying fumes add respiratory exposure, especially in poorly ventilated kitchens.

Safer Ways to Use Oil

Simple habits can limit the risks. Avoid oil that darkens, smokes too quickly, or smells off. Choose stable frying oils, cook at moderate temperatures, and keep deep frying to a single session. Reuse oil only for light cooking, not for another round of frying.

Smart Practices

• Use stable oils like refined sunflower or rice bran.
• Maintain moderate frying temperatures.
• Reuse oil sparingly and only for light dishes.
• Filter out crumbs after each use.
• Ensure good kitchen ventilation.
• Never mix old oil with fresh oil.

Cook Smarter, Stay Healthier

Reused oil quietly affects both flavour and long-term health. Being aware of the warning signs and following safer frying practices helps you enjoy fried foods without compromising your well-being.

Source: The Times of India