Top 10 Unhealthy Cooking Oils to Avoid (and What to Use Instead)

Discover the top 10 unhealthy cooking oils to avoid and explore healthier alternatives you can trust. Learn what makes an oil bad and how to cook smarter.

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Why Your Cooking Oil Matters?

fresh olive oil for preparing pasta — Photo by Ron Lach on Pexels.com

We often pay attention to what we eat—fresh vegetables, lean proteins, fewer sugars. But what about what we cook it in?

Cooking oil is more than just a medium for frying or sautéing. It becomes part of your food. The right oils can support heart health, reduce inflammation, and even boost brain function. The wrong ones? They can do the exact opposite—causing inflammation, raising bad cholesterol, and increasing the risk of chronic disease.

In this guide, you’ll learn about the top 10 unhealthy cooking oils to steer clear of—and which healthier alternatives to choose instead. No fad trends. No overhype. Just facts backed by science and common sense.

What Makes a Cooking Oil “Unhealthy”?

Before we dive into the list, it’s important to understand what makes a cooking oil unhealthy in the first place.

1. Refined and Highly Processed

Unhealthy oils are often refined using heat, chemicals like hexane, and deodorization processes. These strip away nutrients and damage the oil’s structure.

2. High in Omega-6 Fatty Acids

While omega-6 is an essential fatty acid, our modern diets are overloaded with it. When consumed in excess (especially without enough omega-3 to balance it), omega-6s promote chronic inflammation.

3. Low Smoke Point or Easily Oxidized

Many oils break down at high heat, forming toxic compounds and free radicals that harm your body at the cellular level.

Top 10 Unhealthy Cooking Oils to Avoid

Here’s the lineup of the worst offenders in the kitchen—and what’s so wrong with them.

person holding stainless steel cooking pot

1. Vegetable Oil (Generic Blends)

Usually a mix of low-quality oils like soybean, corn, or canola. These blends are cheap, chemically refined, and extremely high in omega-6 fats. Worst of all, the label never tells you what’s really inside.

Health Concern: Triggers inflammation, raises bad cholesterol, and promotes oxidative stress.

2. Canola Oil (Refined)

Although it’s marketed as heart-healthy, refined canola oil is heavily processed, often genetically modified, and has a high omega-6 content.

Health Concern: Linked to metabolic issues and may increase the risk of heart disease when used long-term in large amounts.

3. Soybean Oil

Used in most processed foods. It’s cheap and has an extremely high omega-6 profile.

Health Concern: Studies have linked excessive soybean oil to obesity, insulin resistance, and even brain inflammation.

4. Corn Oil

Another popular industrial oil found in fried snacks and fast food. Highly refined, full of omega-6s, and poor in antioxidants.

Health Concern: Can promote systemic inflammation and may contain pesticide residues if not organic.

5. Sunflower Oil (Refined)

Unrefined sunflower oil isn’t terrible, but the refined versions used for high-heat cooking are oxidized easily and contribute to inflammation.

Health Concern: May form toxic aldehydes at high temperatures.

6. Safflower Oil

Like sunflower oil, safflower oil is high in omega-6s and lacks protective antioxidants.

Health Concern: Promotes imbalance in omega-6 to omega-3 ratios and increases inflammation risk.

7. Cottonseed Oil

Extracted from cotton crops that are often sprayed heavily with pesticides, then refined and bleached. It’s cheap—but at what cost?

Health Concern: May contain toxic residues and trans fats.

8. Grapeseed Oil

Sounds fancy and healthy, but grapeseed oil is a by-product of the wine industry, and it’s heavily processed. It also has one of the highest omega-6 levels among all oils.

Health Concern: Unstable at high heat, can trigger oxidative stress.

9. Palm Oil (Refined)

Used widely in packaged snacks and margarine. Refined palm oil is cheap, high in saturated fats, and often comes from environmentally harmful practices.

Health Concern: Can contribute to heart problems and contains unhealthy trans fats when hydrogenated.

10. Refined Coconut Oil (Overused)

While virgin coconut oil has health benefits, refined versions lose much of the antioxidant value. If overused, it can also increase LDL (bad cholesterol) in some people.

Health Concern: Raises cholesterol if used excessively and lacks nutrients found in virgin versions.

The Real Health Risks of Unhealthy cooking Oils

Still wondering why this matters? Here’s what these oils can actually do over time:

Chronic Inflammation

Too much omega-6 and too many oxidized fats increase inflammation—leading to everything from arthritis and bloating to serious diseases like cancer and heart disease.

Heart Disease

Unhealthy oils can raise LDL (bad cholesterol), lower HDL (good cholesterol), and damage arteries over time.

Cell Damage from Oxidation

When oils break down at high temperatures, they create free radicals. These damage your DNA and speed up aging.

Hormonal Imbalance

Many refined oils interfere with your body’s hormone function, especially in women—affecting everything from your menstrual cycle to mood swings.

Healthier Alternatives: 10 Healthy Cooking Oils You Can Trust

Now for the good news. There are plenty of healthy cooking oils that do nourish your body. These oils are rich in antioxidants, stable at high temperatures, and naturally anti-inflammatory.

1. Extra Virgin Olive Oil (EVOO)

Rich in heart-protective antioxidants and monounsaturated fats. Best for low to medium-heat cooking or salad dressings.

Helps lower blood pressure and supports brain health.

2. Avocado Oil

High smoke point, mild flavor, and loaded with monounsaturated fats. Perfect for roasting or stir-frying.

Supports joint health and reduces cholesterol.

3. Cold-Pressed Coconut Oil

Stable at high temperatures. Contains medium-chain triglycerides (MCTs) that provide quick energy.

May boost metabolism and brain function.

4. Ghee (Clarified Butter)

Traditional Indian cooking fat. High in fat-soluble vitamins and very stable for high-heat cooking.

May support gut lining and digestive health.

5. Mustard Oil (Cold-Pressed)

A staple in Indian kitchens, this oil is rich in omega-3s and has antimicrobial properties.

Great for high-heat cooking and has a distinct flavor.

6. Sesame Oil (Cold-Pressed)

Used in many Asian dishes. It’s rich in antioxidants and has a moderate smoke point.

Contains sesamin, which helps reduce blood pressure and inflammation.

7. Peanut Oil (Unrefined)

Stable for frying, rich in vitamin E and monounsaturated fats. Choose cold-pressed, not refined.

Supports heart health when used in moderation.

8. Rice Bran Oil

Mild in flavor and great for high-heat cooking. Contains oryzanol—a compound known to lower cholesterol.

Light and versatile.

9. Flaxseed Oil

Not for cooking, but amazing for cold uses (salads, smoothies). Extremely rich in omega-3 fatty acids.

Helps reduce inflammation and support brain health.

10. Hemp Seed Oil

Another cold-use oil, hemp oil is balanced in omega-3 and omega-6 fats.

Supports skin, joint, and brain health.