Why Are Seed Oils Bad for You? | Seed Oils and Inflammation

Why are seed oils bad for you? Learn the link between seed oils and inflammation so that you can take control of your health. 

After a few years of chronic pain (that I now suspect were caused by oxalate poisoning), I started having some intense digestive issues. 

I will spare you the details of my bathroom visits, but they weren’t pretty, and they were frequent. 

I started seeing a functional medicine doctor. She helped me identify that I didn’t have any true food allergies, but I had over 50 food sensitivities. 

Being so desperate to get better, I militantly removed every food to which I had a sensitivity out of my diet. It was really hard, and I made some mistakes along the way, like not nourishing myself well with enough minerals and protein. But overall, my digestion improved. 

However, at least once a week, I would still get an upset stomach. Within minutes of eating, my stomach would clench down. I would simultaneously have cramps and get really bloated. 

After keeping a food journal, I realized the common denominator in my reactions was seed oils. I wanted to know if my reactions to these oils was something I could become desensitized to or if they were something I’d want to keep out of my diet long term. 

I didn’t want to restrict my diet unnecessarily. Were seed oils bad for me or was my immune system being hyper reactive? 

So let’s look at what seed oils are, what happens that can make them bad for you, and the effects that can have on your health. 

What Are Seed Oils?

Seed oils are highly processed foods. In order to extract oil from a seed, it has to undergo heat and sometimes even solvents, bleaching, and other toxins. (More on the processing below!) 

Some call them the hateful eight. The oils in the standard American diet that go through these processes are:

1.  Vegetable oil (usually made from corn oil)
2.  Canola oil (also called rapeseed oil)
3.  Cottonseed oil
4.  Rice bran oil
5.  Soybean oil
6.  Peanut oil
7.  Sunflower oil 
8.  Safflower oil

In addition to the eight above, I would also add palm oil because of how it’s processed. 

History of Seed Oils

Initially, humans used seed oils as machine lubricants. But then, we began to revise them to make them more edible and introduced them into our foods and food processing. 

It’s only been about the last 200 years that we’ve manipulated and treated highly processed oils as edible food items. It was primarily in the name of efficiency! 

Here’s more on that process. 

Seed Oil Processing 

Depending on the oil, to turn a seed into an “edible” oil, it may go through: 

• Cleansing – removing impurities 
• Drying – dehydrating water 
• Dehulling – taking the outside layer(s) off 
• Tempering / cooking –  heating to make it shelf stable 
• Solvent extraction or mechanical extraction – helping the oils come out 
• Hydrogenizing – adding hydrogen atoms to turn unsaturated fatty acids into saturated fats so they last longer on the shelf 
• Degumming – removing phospholipids 
• Neutralizing – removing fatty acids 
• Bleaching – removing color 
• Deodorizing – removing odor and taste 

All of the refining above can damage the fats and create harmful byproducts like linoleic acid or trans fats. But more than that, we may lose any beneficial compounds these foods had, like antioxidants. 

For example, hexane is a chemical solvent that processed foods add to help break down the seed to get oil out more efficiently. Supposedly, when the seed oil is heated up, the hexane evaporates, or the majority of it evaporates.¹ But I am skeptical of this. 

Additionally, when we bleach our foods, we may lose antioxidants. But having bleach in my food also concerns me. 

However, food isn’t just fuel. Foods are the building blocks for our body to build new parts. Whatever you eat, your body will use it to replace worn-out cells that make up your organs and other body parts. 

I want to ingest the least inflammatory and most nutritious form of food. I’m skeptical that the processes above yield products that meet those objectives. 

I’m very intentional about optimizing my nutrition after the damage I have from oxalate poisoning.

Cold Pressed Seed Oils

When I use the phrase seed oils, for the sake of clarity, know that I’m not including cold pressed seed oils. 

I do think that some cold-pressed seed oils may be OK for most people. 

Occasionally, I like to enjoy some cold-pressed oil, especially because it is a low-oxalate way to get the same flavor in a homemade salad dressing. 

The key is that the seed has gone through minimal processing–like simply squeezing the oil out of the seed or fruit. More specifically, it should just be washed, crushed, squeezed or spun out, and filtered before put into the glass bottle. 

I try to only eat cold-pressed oils raw because when heated, the fatty acids can turn into lipid oxidation products that are inflammatory.²

Some cold-pressed oils you may cook with at various levels: 

• For cooking are:
  • Avocado oil
  • Coconut oil³
• For raw use are:
  • Flaxseed oil 
  • Walnut oil
  • Sesame oil
  • Grapeseed oil
  • Olive oil

Coconut oil and avocado oil have a high smoke point compared to other cold-pressed oils. 

You’ll want to make sure that these oils come to you from a temperature-controlled environment. And you’ll likely want to keep them in the fridge instead of in your pantry to prevent them from going rancid.

Always check the ingredient label on the back to make sure it is 100 percent just the oil on the front. Otherwise, healthy oils are frequently blended or cut with less healthy oils to make them cheaper. And in the US they legally don’t have to disclose the oil it is cut with if it’s not a top 8 allergen. Eek!

Nevertheless, the whole version of these foods or a cold-pressed oil may be a less inflammatory way to get monounsaturated fats.

So why are seed oils bad for us? 

Why Are Seed Oils Bad For You

Here is the tricky thing: the American Heart Association still says that seed oils are a part of a healthy diet.⁴ However, in my own experience, I’ve not found that to be the case.

Just because something is edible doesn’t make it a nourishing food. Here’s some of the evidence and personal experience that has convinced me not to consume seed oils. 

Even after I healed my leaky gut, I continued to experience immediate inflammation from ingesting seed oils. 

Seed Oils and Inflammation

The science is split about the relationship between seed oils and inflammation. I can only share that in my own experience, seed oils correlate with inflammation. 

After almost eliminating seed oils, my cholesterol went down, along with other markers for cardiovascular disease. (I had already reduced pre diabetes at this point.)  

We’ve also seen the effects of seed oils and inflammation in our family. I have one kiddo that whenever they have a seed oil, even in organic foods, they break out in a rash on their face. 

However, the consistent piece of data is that heating seed oils leads to inflammatory lipid oxidation products.⁵  I suspect that this inflammation triggers my histamine sensitivity.

Omega-3 vs Omega-6 Oils 

You want to optimize your Omega-3 intake and reduce your Omega-6.

The seed oils above are very high in Omega-6. If you consume way more Omega-6 than Omega-3 oils, it’s very inflammatory for your body. It may raise your cholesterol levels and put you at risk for heart disease and weight gain.⁶ 

To get important nutrients like EPA or DHA, I try to get them from meats like salmon that may be more readily available. 

Emulsifiers 

Many processed foods that have seed oils also have emulsifiers that can irritate your gut.⁷ Emulsifiers do work well to keep water and oil from separating. However, studies continue to show that they can increase your inflammation. 

If you pair that with added sugar in other highly processed foods, that can mess with your metabolic health too. 

Genetic Modification 

Humans have dabbled in seed genetics for centuries. However, when we make modifications in order to use toxic pesticides and herbicides on the plants, I am not a fan. 

Most mass-produced seed oils are genetically modified.⁸ And these are for toxic farming practices. 

As a family rule, we try to eat organic as much as possible. This excludes genetically modified seed oils from our diet. 

Related: Learn about how other toxins may push you into Cell Danger Response.

Plastic Packaging 

The other issue is that companies put seed oils in plastic bottles where the endocrine-disrupting chemicals are more likely to leach into your oil, and then you’re eating micro plastics and other harmful compounds. 

However, alternatives to seed oils also come in plastic, so you’ll want to avoid buying oils in plastic bottles too. 

Related: How To Reduce The Use Of Plastic In Your Kitchen

Beyond Seed Oils and Inflammation

Based on all of the above, I learned that seed oils are at the heart of several of my personal issues, and I believe that seed oils are bad for you. Science is just starting to connect the dots on how it’s linked to inflammation. 

So they aren’t something I am going to try to put back into my diet. 

Stay tuned for next month’s post, where you’ll learn how to avoid seed oils and what to use instead that’s less inflammatory. 

More from Pastor SJ

• Mistakes I Made In My Health Journey (And How You Can Do Better!) 
• A Theology of Chronic Illness 
• What Is Medical Gaslighting? How To Recognize It And What To Do

Sources

1. Toxicological Profile for n-Hexane. Atlanta (GA): Agency for Toxic Substances and Disease Registry (US); 1999 Jul. 1, PUBLIC HEALTH STATEMENT. Available from: https://www.ncbi.nlm.nih.gov/books/NBK601195/
2. Zhuang, Y., Dong, J., He, X., Wang, J., Li, C., Dong, L., Zhang, Y., Zhou, X., Wang, H., Yi, Y., & Wang, S. (2022). Impact of Heating Temperature and Fatty Acid Type on the Formation of Lipid Oxidation Products During Thermal Processing. Frontiers in nutrition, 9, 913297. https://doi.org/10.3389/fnut.2022.913297
3. Teng, M., Zhao, Y. J., Khoo, A. L., Yeo, T. C., Yong, Q. W., & Lim, B. P. (2020). Impact of coconut oil consumption on cardiovascular health: a systematic review and meta-analysis. Nutrition Reviews, 78(3), 249–259. https://doi.org/10.1093/nutrit/nuz074
4. https://www.heart.org/en/news/2024/08/20/theres-no-reason-to-avoid-seed-oils-and-plenty-of-reasons-to-eat-them; Harris, W. S., Mozaffarian, D., Rimm, E., Kris-Etherton, P., Rudel, L. L., Appel, L. J., Engler, M. M., Engler, M. B., & Sacks, F. (2009). Omega-6 fatty acids and risk for cardiovascular disease: a science advisory from the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation, 119(6), 902–907. https://doi.org/10.1161/CIRCULATIONAHA.108.191627
5. Le Gresley, A., , Ampem, G., , Grootveld, M., , Percival, B. C., , & Naughton, D. P., (2019). Characterisation of peroxidation products arising from culinary oils exposed to continuous and discontinuous thermal degradation processes. Food & function, 10(12), 7952–7966. https://doi.org/10.1039/c9fo02065a
6. Simopoulos A. P. (2016). An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients, 8(3), 128. https://doi.org/10.3390/nu8030128
7. Naimi, S., Viennois, E., Gewirtz, A.T. et al. Direct impact of commonly used dietary emulsifiers on human gut microbiota. Microbiome 9, 66 (2021). https://doi.org/10.1186/s40168-020-00996-6
8. (2025). GMO crops, animal food, and beyond. U.S. Food and Drug Administration. https://www.fda.gov/food/agricultural-biotechnology/gmo-crops-animal-food-and-beyond 

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