The cooking oil that's quietly inflaming half the country

Picture this.

A 19th-century factory needed a cheap lubricant for its machines. Cotton seeds, sunflower seeds and corn were available in bulk. Engineers worked out how to extract oil from them using high heat, hexane (a petroleum solvent), and chemical bleaching.

The result was a clear, odourless industrial oil. Perfect for pistons. Then, in the 1950s, a clever bit of marketing decided this same liquid was good for your heart.

A century later, your supermarket is drowning in it.

Sunflower oil. Rapeseed oil. Soybean oil. Corn oil. The "vegetable oil" hiding in your salad dressing, mayonnaise, biscuits, ready meals, takeaways, baby food.

Here's what no one tells you. Seed oils are absurdly high in linoleic acid, an omega-6 fatty acid that, in tiny natural amounts, the body uses well. In the doses we now eat, it's a slow-burn fuse for inflammation.

Your great-grandmother consumed about 1g of linoleic acid a day. Today's average is 25-30g. A 25-fold increase in one human's lifetime.

It's showing up as heart disease, fatty liver, type 2 diabetes, rising cancer rates, and stubborn belly fat that won't shift no matter how much cardio you do. The fat in your body cells is now around 25% linoleic acid. It used to be 1-2%.

And it gets worse. When seed oils are heated repeatedly (think the chip shop fryer), they produce aldehydes and trans-fats that damage your DNA.

What to use instead. Butter from grass-fed cows. Ghee. Extra virgin olive oil for cold use. Coconut oil. Beef tallow for high-heat cooking. Yes even lard is ok. Real oils and fats that have been cooked with for thousands of years.

Your action today: Read the label of three things in your kitchen. Crisps, sauces, biscuits, ready meals. Throw out anything where sunflower, rapeseed or "vegetable oil" appears in the top three ingredients.