Can Cooking Oils Affect Gut Health?

Most people think of cooking oils in terms of taste, smoke point, or heart health. But your choice of oil can also influence gut health, from inflammation levels to how well your microbiome functions.

Some oils deliver anti-inflammatory fats that help your gut lining stay strong, while others—especially highly processed oils—may contribute to digestive issues for certain people.

Here’s what to know.

How Cooking Oils Influence Gut Health

Cooking oils affect the gut in three major ways:

1. Inflammation

The ratio of omega-6 to omega-3 fats impacts inflammation. Too many omega-6 fats may promote a pro-inflammatory environment in the gut when eaten in excess.

2. Microbiome Balance

Certain fats support microbial diversity, while others can reduce beneficial bacteria when consumed heavily.

3. Gut Lining Integrity

Healthy fats help maintain the mucosal barrier that protects your intestinal lining.

The Best Cooking Oils for Gut Health

1. Extra-Virgin Olive Oil (EVOO)

Best choice for gut health overall

• Rich in polyphenols that support beneficial gut bacteria

• Anti-inflammatory

• Helps strengthen the gut lining

• Works well for low–medium heat and dressings

Studies show EVOO increases Lactobacillus and Bifidobacterium levels in the gut.

2. Avocado Oil

Great for high-heat cooking

• High in monounsaturated fats

• Supports healthy gut bacteria

• Neutral flavor

• Stable at high temperatures

A strong option if you need a non-olive oil for frying or sautéing.

3. Flaxseed Oil

Best for cold dishes

• Packed with omega-3s

• Can help reduce inflammation in the gut

• May support bowel regularity

Use it in smoothies or dressings — it should not be heated.

4. Walnut Oil

For improving omega-3 intake

• Contains ALA omega-3 fatty acids

• Supports microbial diversity

• Adds rich, nutty flavor

Like flaxseed oil, use it cold only.

5. Coconut Oil

Good in moderation

• Contains medium-chain triglycerides (MCTs)

• May help certain strains of beneficial bacteria

• Easy to digest for many people

Some find coconut oil soothing; others find it too rich. It’s neutral to mildly helpful — not a miracle oil.

Cooking Oils That May Be Harmful for Gut Health

1. Highly Processed Seed Oils

This includes:

• Soybean oil

• Corn oil

• Cottonseed oil

• Sunflower oil (refined)

• Canola oil (refined)

• Safflower oil

• Grapeseed oil

Why they may affect gut health:

• Very high in omega-6 fats

• Often chemically extracted and deodorized

• Can contribute to inflammation when eaten in large amounts

• May alter the gut microbiome when consumed excessively

Important note: These oils are not toxic. The issue is overconsumption and heavy processing, not the oil itself. Small amounts are fine for most people.

2. Hydrogenated Oils / Trans Fats

• Found in some shelf-stable baked goods and fried foods

• Strongly linked to inflammation

• Harm the gut lining and microbiome

These are the oils worth completely avoiding.

How Much Oil Is "Too Much"?

For general gut health:

• Prioritize monounsaturated and omega-3 rich oils

• Limit highly processed omega-6 seed oils

• Use oils at appropriate temperatures to avoid oxidation

• Keep overall fat intake balanced

Balance matters more than perfection.

What About Frying?

Frying — even in good oils — is harsh on the gut for two reasons:

1. High heat oxidizes oils, creating compounds that irritate the gut

2. Fried foods slow gastric emptying, causing bloating for many people

If you fry, choose:

• Avocado oil

• High-oleic sunflower oil

• Refined olive oil

And avoid reusing the oil.

Best Choices for Different Cooking Styles

Cooking Style	Best Oil	Why
Salad dressings	EVOO, flaxseed oil, walnut oil	High polyphenols, anti-inflammatory
Sautéing	EVOO, avocado oil	Stable at moderate heat
High-heat frying	Avocado oil	High smoke point
Baking	Olive oil, avocado oil	Neutral, stable
Smoothies	Flaxseed or walnut oil	Boosts omega-3s

Key Takeaways

• Yes, cooking oils can affect gut health.

• Choose oils rich in monounsaturated fats, polyphenols, and omega-3s.

• Limit heavily processed seed oils — not because they’re “poison,” but because heavy use may promote inflammation.

• Use flaxseed and walnut oils cold; avocado and olive oil for most cooking.

• A balanced diet matters more than any single oil.