These 3 Types of Olive Oil Are Unhealthy! Doctor Reveals How They Accelerate Brain Aging—and 3 Tips to Choose Healthy Oil

Editor's note: Choosing the wrong olive oil could make you dumber! Not all olive oils are healthy—picking the wrong type might actually cause your brain to 'degenerate faster with every bite.' Recently, neurologist and brain science PhD Dr. Cheng Chun-Yu issued a warning, citing a 2026 international study: people who consume 'refined olive oil' long-term show signs of declining cognitive function.

Dr. Cheng points out that olive oils labeled 'Pure,' 'Light,' or 'Pomace' on the market are actually misleading. To truly protect your brain, you must look for 'Extra Virgin,' 'Virgin,' or 'cold-pressed or cold-extracted first-pressed' virgin olive oil.

Not all olive oils are created equal—latest research: choosing the wrong type accelerates brain aging!

"Doctor, olive oil is healthy, right? I use it every day!" I usually ask one more question: "Which kind do you use?"

Not all 'olive oil' equals 'healthy'! Today, I’ll share an important study published in early 2026: choosing the wrong type of olive oil not only fails to protect your brain—it may actually speed up cognitive decline!

Not all olive oils are the same

In January 2026, a research team from Spain’s Rovira i Virgili University published a two-year longitudinal study in the prestigious journal Microbiome, revealing:

1. Virgin olive oil supports brain health: Overall cognitive function, language, and executive function improved over two years. Higher intake correlated with greater gut microbiome diversity.

2. Refined olive oil may accelerate decline: Executive function, language, and overall cognition showed signs of deterioration, and gut microbiome diversity decreased.

3. Gut microbiota may be the key link: The study identified a critical gut bacterium, Adlercreutzia. The more virgin olive oil consumed, the lower the levels of this bacterium—and the better the cognitive performance. This suggests olive oil may first affect gut bacteria, then influence brain function via the 'gut-brain axis.'

(Image provided by Dr. Cheng Chun-Yu)

Why such a big difference between olive oils?

First, let’s understand the two types of olive oil and their production methods discussed in the study:

1. 'Virgin olive oil': Includes extra virgin and regular virgin olive oil (Virgin Olive Oil, VOO)

Any oil labeled 'virgin' must be extracted through 'pure physical and mechanical' means, without high heat that degrades the oil or chemical solvents. Ideally, it should also be 'cold-pressed' or 'cold-extracted.'

2. 'Common refined olive oil': Includes refined olive oil and pomace oil (Common Olive Oil, COO)

The raw material may be low-quality or high-acidity olives, which undergo 'chemical industrial refining'—deacidification, decolorization, and high-temperature deodorization—to become edible oil.

In short, virgin olive oil retains 'rich polyphenols, antioxidants, and vitamins' due to its 'low-temperature, physical extraction' process, offering anti-inflammatory and neuroprotective benefits. Refined oil, however, loses these components during processing, and the 'chemical and high-heat process' may even degrade the oil.

3 Smart Tips for Consuming Olive Oil

Step 1: How I choose mine

• Choose the right type: Look for 'Extra Virgin' or 'Virgin' on the label. 'Cold-pressed or cold-extracted first-pressed' is even better.

• Avoid the traps: Steer clear of labels marked 'Pure,' 'Light,' or 'Pomace' olive oil—these are mostly refined-grade oils. Note: 'Light' doesn’t mean lower calories; it refers to refined oil with a milder flavor.

• Choose the right packaging: Opt for dark glass bottles or metal cans to block light and prevent polyphenol oxidation. Avoid transparent plastic bottles.

• Learn to read labels: Check harvest and production dates. Early-harvest green olives are fresher and richer in polyphenols. Prioritize single-origin oils with clear regional labeling.

Step 2: How I use it daily—cooking methods

• High-heat cooking: Many think virgin olive oil is only for dressings, but high-quality oil can be used for stir-frying—just avoid high-heat searing or heating until it smokes. Check the smoke point on the label (typically 180–210°C); medium or low heat is safe.

• Great for dressings and dips: Mix with soy sauce or balsamic vinegar for dipping, or use as a sauce for blanched vegetables, cold salads, or raw greens.

• Enhance flavor and texture: Drizzle a bit of high-quality virgin olive oil over dishes just before serving—it elevates flavor and smoothness. Works great on vegetables, meats, soups, nuts, and whole grains.

Step 3: Pair with a balanced diet

• The protective benefits of olive oil are maximized when combined with plenty of vegetables, legumes, whole grains, fish, and nuts.

• At the same time, reduce: refined carbohydrates, processed foods, sugary drinks, and sweets. These damage gut microbiota and cancel out the benefits of olive oil.

Don’t fear oil

Eating good fats actually protects your brain and heart—but you must choose the right oil and use it correctly. Not all olive oils are the same. Go check the label on your kitchen olive oil right now!