Cooking oil peroxidation causes Alzheimer’s: pubmed.ncbi.nlm.nih.gov/37693644/

Given the tremendous number of worldwide people suffering various lifestyle-related diseases, it is valuable to consider how ω-6 PUFA-rich vegetable oils is implicated for the organ disorder. https://pubmed.ncbi.nlm.nih.gov/36819480/

Linoleic Acid and Its Susceptibility to Peroxidation
Linoleic acid (LA) (found in soybean, corn, sunflower oil) is a polyunsaturated fatty acid (PUFA) with two double bonds in its structure, making it highly susceptible to oxidation and peroxidation when exposed to heat, light, or oxygen.

🧪 Why Is Linoleic Acid Prone to Peroxidation?
Peroxidation refers to the process where unsaturated fatty acids react with oxygen, leading to the formation of lipid peroxides and free radicals, which can degrade oil quality and have potential health risks.

Linoleic acid is particularly vulnerable due to:
Multiple Double Bonds:
PUFAs like linoleic acid have unstable double bonds, which can react with oxygen.
The more double bonds, the greater the oxidation risk (linoleic acid has two, whereas more stable fats like oleic acid have only one).

High Rate of Hydrogen Abstraction:
The hydrogen atoms near the double bonds are easily removed, initiating the peroxidation chain reaction.

Influence of Heat, Light, and Air:
High temperatures (frying or prolonged cooking) accelerate oxidation.
Exposure to air increases the formation of hydroperoxides.
UV light speeds up peroxidation by generating free radicals.

🔬 Oxidative Stability of Linoleic Acid vs. Other Fats
Fat/Oil Type
Major Fatty Acid
Double Bonds
Oxidation Stability
Linoleic Acid (LA) (found in soybean, corn, sunflower oil)
C18:2 (2 double bonds)
Highly unstable 🔥

Oleic Acid (found in olive oil, avocado oil)
C18:1 (1 double bond)
Moderately stable 🟡

Stearic Acid (found in beef fat, cocoa butter)
C18:0 (saturated, no double bonds)
Very stable ✅

Alpha-Linolenic Acid (ALA) (found in flaxseed oil, chia seeds)
C18:3 (3 double bonds)
Extremely unstable ⚠️

🔹 Saturated fats are the most stable, while PUFAs like linoleic acid oxidize rapidly.

🛠️ How to Reduce Peroxidation in Linoleic Acid Oils
Avoid High Heat Cooking:
Linoleic acid-rich oils (soybean, sunflower, safflower, corn) are not suitable for frying.
Opt for olive oil, coconut oil, or ghee for high-heat cooking.
Store Oils Properly:
Keep oils in dark, airtight glass bottles to minimize oxygen and light exposure.
Refrigerate high-linoleic oils (like flaxseed oil) to slow oxidation.
Use Antioxidants:
Vitamin E (tocopherols), rosemary extract, and polyphenols help stabilize linoleic acid.
Some natural oils (like extra virgin olive oil) contain phenolic compounds that reduce peroxidation.
Limit Storage Time:
Fresh oils are less oxidized—avoid storing linoleic acid-rich oils for months at room temperature.

⚠️ Health Implications of Linoleic Acid Peroxidation
When linoleic acid oxidizes, it forms:
Lipid Peroxides → Can damage cell membranes and proteins.
Advanced Lipid Oxidation End Products (ALEs) → Linked to inflammation, oxidative stress, and chronic diseases like cardiovascular disease.
Trans Fats and Aldehydes → Some oxidation byproducts, like 4-hydroxynonenal (4-HNE), are potentially toxic and carcinogenic.
📌 Key Takeaway: While linoleic acid itself is not inherently harmful, its oxidation products can be damaging if consumed in excess or from poorly stored and overheated oils.

🏁 Final Verdict: Is Linoleic Acid Stable?
❌ No, linoleic acid is highly prone to peroxidation.
✔️ It should be used cautiously—avoid high-heat cooking, store properly, and balance intake with more stable fats like monounsaturated (olive oil) and saturated fats (butter, coconut oil).

🔥 Best Cooking Oils Based on Heat Stability

Choosing the right cooking oil is essential for health and flavor while avoiding harmful oxidation. Different oils perform best at different heat levels, depending on their fatty acid composition and smoke point. Here’s a guide to selecting the best oils for various cooking methods.

🏆 Best Oils for High-Heat Cooking (Frying, Searing, Grilling)
These oils are heat-stable and resistant to oxidation at high temperatures.

💡 Why These Are Best:
High in saturated and monounsaturated fats, making them resistant to oxidation.
Minimal polyunsaturated fats (PUFAs), which oxidize easily at high temperatures.

🍳 Best Oils for Medium-Heat Cooking (Sautéing, Baking, Light Stir-Frying)
These oils are moderately heat-stable but should not be used for deep frying.

💡 Why These Are Good for Medium Heat:
Monounsaturated fats (MUFAs) are stable at moderate temperatures.
Extra virgin olive oil contains polyphenols and antioxidants, reducing oxidation risk.
Avoid prolonged high-heat cooking to prevent oxidation.

🥗 Best Oils for Low-Heat Cooking or Raw Uses (Salads, Drizzling, Dips)
These oils should never be heated due to their high polyunsaturated fat (PUFA) content, which oxidizes easily.

💡 Why Use These Only for Cold Dishes:
High PUFA content makes them prone to rapid oxidation when heated.
Flaxseed and walnut oils provide beneficial omega-3 fatty acids but should be stored in the refrigerator.
Never use these oils for frying or roasting!

❌ Oils to Avoid for Cooking
These oils are high in omega-6 PUFAs, making them unstable and prone to oxidation at cooking temperatures.

🏁 Final Recommendations
✔️ For High Heat: Avocado oil, ghee, coconut oil, tallow
✔️ For Medium Heat: Extra virgin olive oil, butter
✔️ For Cold Uses: Flaxseed oil, walnut oil, sunflower oil (unrefined)
❌ Avoid High-PUFA Oils for Cooking: Soybean, corn, generic vegetable oils