Common cooking oils may silently harm your heart health, experts warn

Many common cooking oils could be harming heart health, according to recent research. Oils like soy, corn, and sunflower—often used in kitchens—become unstable when heated, forming harmful compounds. Experts now recommend switching to more stable fats, particularly saturated ones, which resist oxidation and may support long-term heart health.

For decades, saturated fats were blamed for heart disease after Ancel Keys' Diet-Heart Hypothesis in the 1950s. His research, however, relied on cherry-picked data and oversimplified the link between fat and heart health. Over time, studies have shown that not all saturated fats behave the same way. Recent meta-analyses from the 2010s and 2020s reveal that their impact depends on the food source, diet quality, and type of fat—with some, like those in dairy, even showing neutral or protective effects on heart health.

The real concern lies with unstable seed and vegetable oils. When exposed to heat or stored for long periods, these oils oxidise, creating harmful lipids and trans fats. Oxidation damages arteries and contributes to atherosclerosis, a key factor in heart disease. Saturated fats, on the other hand, remain stable due to their chemical structure, lacking the double bonds that make other fats vulnerable.

Historically, humans cooked with saturated fats like tallow, lard, butter, and coconut oil. These fats were staples in traditional diets long before processed seed oils became widespread. Today, nutritionists suggest returning to these options for high-heat cooking. Grass-fed tallow, pastured lard, ghee, and organic coconut oil are now recommended for frying and sautéing. Extra-virgin olive oil, while healthy, should be reserved for dressings or drizzling—never heated—to prevent oxidation.

The shift in advice means rethinking common cooking habits. Stable saturated fats offer a safer alternative to unstable seed oils, reducing the risk of oxidation-related damage. With modern research debunking old myths, the focus now centres on food quality and overall diet rather than blanket restrictions on fat.