Are Seed Oils Inflammatory?

Mar 10, 2022

Are Seed Oils Good or Bad For You?

Do seed oils and vegetable oils actually cause inflammation or heart disease? Or is that a myth? Are there any research studies on this topic? Yes, thankfully we have tons of studies on this now. The seed oil debate ends now! 

Seed Oils Are Cardioprotective (Good For Your Heart)!

You always hear "Instagram Doctors" and other internet health gurus talk about seed oils causing inflammation and leading to chronic disease. Are these internet gurus and doctors right?

Unfortunately they are not. Not at all! Not even one bit. They are just trying to scare people with the "next thing", sort of like telling people that drinking "still water" or "alkaline water" or "juice cleanses" will actually do anything to improve your health. They just put a hole in your pocket.

There is an overwhelming amount of data and science that shows that seed oils are cardioprotective. This means that they offer improvements in cardiovascular disease and improve your heart health. The largest study done on seed oils is listed below.

To date, there have no human outcomes trials that have shown harm from seed oils. Not one. When I asked on social media for people to post one single study that shows harm from seed oils, all I got in return was crickets. Not one study shows harm.

Is Olive Oil a Seed Oil?

Olive oil is not classified as a seed oil. It's actually derived from the fruit of the olive tree or the "olive". It falls under the category of "fruit oils". Research articles like the one published in the Journal of Agricultural and Food Chemistry confirm the origins of olive oil, emphasizing its extraction from the olive fruit rather than seeds.

Historically, studies have shown that olive oil offers unique health benefits, primarily due to its high content of monounsaturated fats, antioxidants, and anti-inflammatory properties. This distinction is significant when discussing the impact of different oil types on health and heart-related issues.

Seed Oils Research, Debates, Science, Studies

As a cardiologist, I often encounter patients curious about the effects of seed oils on their health, especially concerning their hearts. The use of seed oils, extracted from various seeds like soybean, sunflower, corn, and others, has surged due to their affordability and purported health benefits.

However, the debate persists: Are seed oils truly beneficial, or do they pose risks to our well-being, particularly heart health?

To navigate this topic, let's delve into scientific studies and empirical evidence to address the pressing questions: Are seed oils good or bad for you? Do they contribute to inflammation? And how do they impact heart health?

One of the internet doctors that talks about this extensively actually cites a rat study from 1965. Yes, a rat study from 1965. That's almost 60 years ago now and we have over 30 human studies that tested this exact thing and answered this exact question.

The nice thing about science is that you can answer the exact question you have. And in the last 5-10 years we have answered almost all health, diet, exercise, and nutrition based questions. Sure, there's still more and we need to dive into the detail and nuance now, but we have most of the answers.

Do Seed Oils Cause Inflammation?

It turns out that seed oils actually reduce inflammation and improve cardiovascular mortality significantly. Watch this video, as I go over the studies.



Understanding Seed Oils

Seed oils or vegetable oils, derived from seeds of plants, are primarily divided into two categories: polyunsaturated and monounsaturated fats. They are often rich in omega-6 fatty acids, essential for the body's functions. Common examples include sunflower oil, soybean oil, canola oil, and corn oil. When most of the online pundits talk about "seed oils" they are talking about canola oil or oils with linoleic acid.

Are Seed Oils Good for You?

Seed oils offer essential fatty acids vital for bodily functions. When you substitute a saturated fat for a seed oil in your diet, all studies show improved health outcomes. Seed oil's impact on overall health is no longer a subject of debate. Several studies have highlighted potential benefits associated with omega-6 fatty acids found in seed oils. These acids are essential for brain function, skin health, and metabolism regulation. There isn't a single human outcome trial that shows that seed oils may be harmful to humans.

A study published in the Journal of Nutrition in 2013 suggested that linoleic acid, abundant in seed oils, might aid in reducing the risk of heart disease. It emphasized that replacing saturated fats with polyunsaturated fats, such as those found in seed oils, could lower the risk of cardiovascular issues.

Do Seed Oils Cause Inflammation?

Seed oils have been shown to reduce inflammatory markers in nearly every study on inflammation. This is especially true if substituting saturated fat for MUFAs ad PUFAs.

Inflammation serves as the body's defense mechanism against infections and injuries. However, chronic inflammation can contribute to various health problems, including cardiovascular diseases. The omega-6 fatty acids in seed oils can lead to the reduction of pro-inflammatory molecules.

Recent studies published in reputable journals like Nutrients have explored the impact of seed oils on inflammation, suggesting that certain seed oils may possess anti-inflammatory properties. For instance, research conducted on oils rich in omega-6 fatty acids, such as linoleic acid found in safflower oil and others, has shown potential anti-inflammatory effects. A study in The Journal of Nutrition observed that linoleic acid from seed oils might decrease inflammation markers in the body.

Similarly, findings in the European Journal of Clinical Nutrition indicate that consuming omega-6 fatty acids from seed oils might even help reduce inflammation in individuals with certain health conditions. These studies challenge the common assumption that all seed oils contribute to inflammation and emphasize the nuanced impact of specific types of seed oils on inflammation markers.

Are Seed Oils Bad for Your Heart?

The impact of seed oils on heart health is unquestionable. Nearly, all studies on seed oils (MUFAs and PUFAs) suggest benefits. There are no studies raise concerns about their potential adverse effects. Research published in the American Journal of Clinical Nutrition indicated that substituting saturated fats with polyunsaturated fats from seed oils might lower LDL cholesterol, often referred to as "bad" cholesterol, potentially reducing the risk of heart disease.


Are Seed Oils Bad For Your Heart Or Health?

Seed oils are cardioprotective. Period.

Let’s take this head on.

Nearly every Medfluencer who is on social media keeps talking about seed oils and vegetable oils. They are referring to oils that are derived from seeds like safflower, sunflower, peanut, canola, and many others. These oils are high in omega 6 fatty acids, specifically linoleic acid.

Medfluencers try to scare the public into avoiding seed oils and instead, buy their supplements. They cite one rat study from 1965. Which is absurd given the amount of human data we have on seed oils.

Or they cite many of the studies mentioned in other parts of this book on saturated fat versus unsaturated fats.

Let’s be clear…

Rats are not humans.

Petri dishes are not human.

Test tubes are not human.

We do not need to use rat studies and petri dish studies when we have actual human outcome studies. They often cite some very flawed small studies that we have already discussed.

But first let’s look at the human outcomes studies on seed oils that show benefit.

Multiple studies now show that “Seed Oils” (Linoleic acid, LA, and AA) reduce CVD.

Perhaps the most comprehensive was published in Circulation. Circulation is one of the most respected peer reviewed journals. It’s very difficult to get past their editorial board and publish your work. Trust me, I’ve done research in a lab, and I know.

The study looked at over 68k participants for 31.9 years of follow up and the endpoints were reached over 15k times. They had 76k tissue biopsies to make sure the linoleic acid group was actually consuming linoleic acid (seed oils). They looked at blood and adipose tissue samples to confirm consumption of linoleic acid. You can’t really beat the design.

You can read it here: 

Results from the study verbatim:
“In 30 prospective studies with medians of follow-up ranging 2.5 to 31.9 years, 15,198 incident cardiovascular events occurred among 68,659 participants. Higher levels of LA were significantly associated with lower risks of total CVD, cardiovascular mortality, and ischemic stroke, with hazard ratios per interquintile range of 0.93 (95% CI, 0.88–0.99), 0.78 (0.70–0.85), and 0.88 (0.79–0.98), respectively, and nonsignificantly with lower coronary heart disease risk (0.94; 0.88–1.00). Relationships were similar for LA evaluated across quintiles. AA levels were not associated with higher risk of cardiovascular outcomes; in a comparison of extreme quintiles, higher levels were associated with lower risk of total CVD (0.92; 0.86–0.99). No consistent heterogeneity by population subgroups was identified in the observed relationships.

In pooled global analyses, higher in vivo circulating and tissue levels of LA and possibly AA were associated with lower risk of major cardiovascular events. These results support a favorable role for LA in CVD prevention.”

That’s definitive and overwhelming evidence. There are no human outcome trials that show harm from seed oil.

Read that again.

There isn’t a single human outcome trial that shows harm from seed oils.

Not one.

In fact, there are many trials that show benefit. It’s not news. We have always known that MUFAs and PUFAs are cardioprotective. It’s an overwhelming amount of evidence. Nearly every study that has been done has shown that MUFA and PUFA are beneficial.


What About Butter For Seed Oil Substitution Studies?

This is especially true when substituting saturated fat (butter) for a PUFA. The benefits are undeniable.

Let’s examine some of these studies.

One study found that soybean oil lowers circulating cholesterol levels and coronary heart disease risk and has no effect on markers of inflammation and oxidation. You can read it: 

Another study found that when you substitute saturated fat for poly unsaturated fat that you improve flow mediated dilation and reduce inflammation. In this study, a high saturated fat diet increased inflammation and flow-mediated dilation compared to high PUFAs, MUFAs, and or a high-carbohydrate diet. We have discussed some of this in parts of the book discussing saturated fat.

Another study found that substituting saturated fat for seed oils (rapeseed and sunflower) in a 1 to 1 ratio (isocaloric) showed a 5-7% reduction in LDL-C, apoB, and total cholesterol.

Another study demonstrated that replacing saturated fat with PUFAs or carbohydrates was associated with a reduction in cardiovascular disease in adults with type 2 diabetes. Yes, those with insulin resistance did better on seed oils. After 9.8 years of follow up, there was a 13% reduction in heart disease for only a 2% replacement of saturated fat for PUFAs and 18% for a 5% replacement with carbohydrates. Those with higher levels of seed oil intake actually had a 25% relative risk reduction in CVD.

Another large study published in Circulation showed that linoleic acid (LA) consumption was inversely correlated with CVD. When the highest category was compared with the lowest category, dietary LA was associated with a 15% lower risk of CV events and 21% reduction in CV deaths. A 5% of energy increment in LA intake replacing energy from saturated fat intake was associated with a 9% lower risk of CV events and a 13% reduction in CV deaths.

They have also done crossover studies with saturated fat, MUFAs, and PUFAs. ApoB and LDL-C levels both dropped on the PUFA diet. At the end of the study, the authors concluded that the most important risk factor modification is to reduce saturated fat intake,

Another study examined the metabolic effects of saturated fats versus seed oils (PUFAs) in ketogenic diets. They found that a ketogenic diet where they substituted saturated fat for PUFA actually induced better ketosis without raising total cholesterol or LDL-C. PUFA also improved insulin sensitivity.

Studies have also found that seed oils improved insulin sensitivity. In one study the authors found that, “The evidence suggests that replacing saturated fats and trans fatty acids with unsaturated (polyunsaturated and/or monounsaturated) fats has beneficial effects on insulin sensitivity and is likely to reduce risk of type 2 diabetes. Among polyunsaturated fats, linoleic acid from the n-6 series improves insulin sensitivity”.


What About Non Alcoholic Fatty Liver Disease NAFLD And Seed Oils?

As we have discussed in other sections, PUFAs reduce liver fat significantly when replacing saturated fats.


Do Seed Oils Cause Weight Gain?

In an interesting plot twist, there was a study that found that people who added seed oils during the holiday season were less likely to gain weight and maintained that benefit for 6 months.
Read the study here: 

Another study found that consuming seed oil (sunflower) reduced body fat in those with obesity. They consumed 500 calories from sunflower seed oil for 12 weeks and had reductions in body weight, adipose tissue, adipogenesis, and waist circumference.

Another study also found that supplementing with seed oil reduced body fat mass and increased lean body mass in overweight and obese adults. 


Are Seed Oils Healthier Than Olive Oil?

Another meta-analysis from November 2023 found that canola oil reduced LDL-C more than olive oil. Canola oil reduced LDL-C by 6.13 mg/dL (weighted mean difference) compared to olive oil.

A meta-regression analysis by Mensink found that isocaloric substitutions of carbohydrates for oleic acid (the main fatty acid found in olive, pecan, canola, peanut, macadamia, sunflower, and grapeseed oil) decreased LDL-C, HDL-C, and triglycerides substantially.


Do Seed Oils Cause Cancer?

Seed oils do not increase the risk of cancer and may even reduce the risk of cancer.



Final Thoughts on Seed Oils and Cardiovascular Disease

The impact of seed oils on health, particularly heart health, is a multifaceted issue. While they offer essential fatty acids and potential benefits when replacing saturated fats, excessive consumption, especially without a balanced intake of omega-3 fatty acids, may contribute to inflammation and potentially adverse health effects.

As a cardiologist, I recommend mainly eating a Mediterranean style diet and to keep fat intake lower. I don't recommend overloading your food with oils, because that will add calories to your food. However, if you don't have access to olive oil, then using other forms of vegetable oil are acceptable.

I recommend moderation in consuming all oils, including seed oils, and emphasize a well-balanced diet rich in diverse nutrients, including omega-3 fatty acids. 

Studies on Seed Oils and Heart Disease

The best article to look at this and answer this exact question was the article in Circulation that looked at 30 prospective studies on seed oils and inflammation. It's the first study listed below. They followed 68k people around for 31.9 years, took 76k tissue biopsies, and where the endpoints were reached over 15k times. Without question, seed oils were cardioprotective.

Some argue that linoleic acid converts to arachidonic acid and that causes inflammation, but that isn't true either. Very little conversion takes place in humans. That study is listed below as well.

If you like to read the data yourself, click on the links below.


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References and studies: 


  • Mozaffarian D, Wu JH. (2011). Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events. Journal of the American College of Cardiology.
  • Simopoulos AP. (2016). An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients.
More studies for homework: 

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