Seed Oils: Which to Avoid, Which Are Okay and What to Use Instead
Updated: Nov 2
The quick answer: The seed oils most worth avoiding are corn, soybean, canola, cottonseed, grapeseed and rice bran oil. They're highly refined, processed with heat and solvents, and found in most fried and packaged foods. Better everyday choices are extra virgin olive oil, avocado oil, macadamia nut oil, butter or ghee.
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If you do one thing for your health, give yourself an oil change. ~ Coach❤️Theah
What are seed oils?
Seed oils are vegetable oils pressed or extracted from seeds, including:
Canola
Corn
Soybean
Cottonseed
Grapeseed
Sunflower and safflower
Peanut
Rice bran
These oils are cheap, which is why restaurants use them for frying, dressings and sauces, and why they show up in almost every processed food. Read your ingredient labels. You'll be surprised how often you find them!
What's the real problem with seed oils?
For years, seed oils were blamed mostly for being high in omega-6 fats. Most of us now eat far more omega-6 than omega-3, a balance that may drive inflammation. But I believe the bigger problem is how these oils are made.
Many seed oils are extracted with chemical solvents like hexane, heated to high temperatures, bleached and deodorized. These polyunsaturated fats are also less stable, so they oxidize more easily, especially when they're reheated again and again in restaurant fryers. Linoleic acid, the main fat in most seed oils, can stay stored in your body fat for about two years, so what you eat today sticks around.
It's not the seeds. It's the solvents, the rancidity and the chemical processing.
What does the research say?
To be fair, this topic is debated. Major health organizations, like the American Heart Association, still consider vegetable oils a heart-healthy swap for saturated fat. Other researchers raise concerns about heavy processing, oxidation at high heat, and the ultra-processed foods these oils come in. Where almost everyone agrees: eating fewer fried and ultra-processed foods is good for you. That's exactly what cutting seed oils helps you do.
Seed oils ranked: avoid, limit or use
Oil | Verdict | Why |
Corn oil | Avoid | Highly refined; omega-6 to omega-3 ratio of about 46:1 |
Soybean oil | Avoid | Highly refined; in most processed foods and fryers |
Canola oil | Avoid | Heavily processed and deodorized; common in restaurants |
Cottonseed, grapeseed, rice bran | Avoid | Highly refined, high in omega-6 |
Sunflower / safflower | Limit | Choose high-oleic versions, which are more stable |
Peanut oil | Limit | Fine occasionally, especially unrefined |
Palm oil | Limit | Unrefined (red) palm is stable; avoid refined versions |
Sesame oil | Limit | Rich in antioxidants; great for drizzling, not high heat |
Flaxseed oil | Limit | High in omega-3; never heat it |
Extra virgin olive oil | Use | Rich in antioxidants; drizzling and light cooking |
Avocado oil | Use | High smoke point; great for high-heat cooking |
Macadamia nut oil | Use | Buttery and low in omega-6 |
Butter, ghee, coconut oil | Use | Stable for cooking; enjoy in moderation |
Avoid completely
These are the worst offenders: highly processed and chemically altered.
1. Corn oil
Extracted with hexane and highly refined
Usually made from GMO corn
Omega-6 to omega-3 ratio of about 46:1
Found in chips, tortillas and fast food fryers
2. Soybean oil
The most-used oil in processed food in the U.S.
High-heat deodorizing can create small amounts of trans fats, even in oils labeled "non-hydrogenated"
Linked in research to weight gain and blood sugar problems when eaten in excess
3. Canola oil
Heavily refined and deodorized, and may contain trace solvent residues
Common in restaurants and packaged foods
Even expeller-pressed canola isn't my first choice
Limit to occasional use
Use these in small amounts, and only if they're unrefined or high quality.
4. Palm oil
Unrefined (red) palm oil is stable for cooking. Refined versions lose their nutrients and are highly processed, so avoid them unless clearly labeled.
5. Sunflower and safflower oil
Look for "high-oleic" on the label. These versions are higher in stable monounsaturated fat and handle heat better. Fine for occasional cooking, not daily use.
6. Sesame oil (especially toasted)
High in antioxidants and full of flavor. Some small studies suggest it may help with blood sugar and inflammation. Great for drizzling, not for high-heat cooking. A few times a week is fine.
7. Flaxseed oil
High in plant omega-3 (ALA), but very unstable under heat. Never cook with it; drizzle it on cool foods instead.
The best fats to use instead
These are the gold standard: clean, stable and body-friendly.
Extra virgin olive oil: monounsaturated and rich in antioxidants. Great for drizzling and light sautéing.
Avocado oil: high smoke point, excellent for high-heat cooking.
Macadamia nut oil: buttery and low in polyunsaturated fat. Best raw.
Butter and ghee: from grass-fed cows if you can. Ghee is great for high heat.
Coconut oil: mostly medium-chain saturated fats, which your body uses differently. Enjoy it, just don't go overboard.
Zero Acre Oil: my favorite! It's made by fermentation (not seeds), very low in polyunsaturated fat, high in monounsaturated fat and very heat-stable. Learn more at zeroacre.com.
Download my Healthy Fats guide
Why your body needs healthy fat
Like protein and carbs, fat is a macronutrient your body needs. It's all about the right kinds of fat, in the right amounts. Healthy fat helps your body:
Make hormones
Create energy and support cell growth
Protect your organs
Absorb vitamins A, D, E and K
Feel full and satisfied
Support brain health
Learn more in Coach Theah's Guide to Healthy Fats.
How to give yourself an oil change
Read every label. Look for soybean, canola, corn, cottonseed and "vegetable oil" in dressings, mayo, chips, crackers and snacks.
Swap your pantry oils for olive oil, avocado oil, butter or ghee. See my pantry purge list.
Buy avocado oil versions of mayo, dressings and chips.
Cook more at home. That's where you control the oil.
Eat out smarter: choose grilled over fried, ask for olive oil and vinegar, and ask what the kitchen cooks with.
Final takeaways
Avoid: corn, canola, soybean, cottonseed, grapeseed and rice bran oil.
Limit: palm, sunflower, safflower, peanut, sesame and flax, and only unrefined, expeller-pressed or high-oleic versions.
Use: extra virgin olive oil, avocado oil, macadamia oil, butter, ghee and Zero Acre Oil, your best everyday fats.
Seed oil FAQ
What are the worst seed oils?
Corn, soybean, canola, cottonseed, grapeseed and rice bran oil are the most heavily refined and the most common in fried and processed foods.
Is olive oil a seed oil?
No. Olive oil is pressed from the olive fruit, not seeds, and extra virgin olive oil isn't chemically refined.
Is avocado oil a seed oil?
No. Avocado oil comes from the fruit's flesh. It's mostly monounsaturated fat and has a high smoke point, so it's great for cooking.
Are seed oils really bad for you?
It's debated. Major health groups consider them safe, but many experts worry about heavy processing, oxidation at high heat and the ultra-processed foods they're found in. Cutting them back is an easy way to eat more whole food.
What's the healthiest oil for high-heat cooking?
Avocado oil and ghee both handle high heat well. Extra virgin olive oil is great for everyday sautéing. Learn more about smoke points in A Guide to Cooking with Fats & Oils.
Keep learning
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Disclaimer: This content is for education only and is not medical advice. Please talk with your doctor before making major changes to your diet.
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