Are Seed Oils Ruining Your Health? Here’s the Truth with Jeff Krasno

Seed oils are having a moment, and not in a good way.

If you’ve scrolled through wellness TikTok or Instagram lately, you’ve probably seen warnings that “seed oils are toxic” or that they “cause inflammation.” 

On the flip side, animal fats like tallow and butter are making a comeback as healthier, “natural” alternatives.

But is swapping your canola for tallow actually better for you?

Let’s look at what the evidence says, not the algorithms.

What Are “Seed Oils” Anyway?

When people say seed oils, they’re usually talking about oils extracted from seeds, like soybean, corn, safflower, sunflower, cottonseed, and canola.

Seed oils are rich in polyunsaturated fatty acids (PUFAs), especially linoleic acid, an essential omega-6 fat your body can’t make on its own. 

Linoleic acid plays a role in skin health, immune function, and cell membrane integrity, and deficiency, though rare, can lead to dry skin, hair loss, and poor wound healing.

By contrast, animal fats like tallow, lard, and butter are mostly saturated fat with smaller amounts of monounsaturated fat.

The Tallow Trend: Where It Comes From

The push toward animal fats comes largely from social media claims that seed oils cause inflammation, obesity, and heart disease, while animal fats are “ancestral” and therefore better for you.

It’s an appealing story.

But the best evidence we have, decades of controlled feeding studies and large population data, tells a different story.

What the Research Actually Shows

Replacing Saturated Fat With Polyunsaturated Fat Improves Heart Health

When you replace saturated fats (like tallow or butter) with polyunsaturated fats (like those in seed oils), your LDL cholesterol and cardiovascular risk go down.

• Cochrane Review (2020) – 15 randomized trials, over 56,000 people: Cutting saturated fat and replacing it with PUFA reduced cardiovascular events by ~17%.

• American Heart Association (AHA) – Replacing saturated fat with PUFA lowers risk of heart disease by about 30%.

• Zhang et al., 2021 (BMC Medicine) – People who used corn, canola, or olive oil instead of butter had lower rates of cardiovascular disease, diabetes, and even Alzheimer’s disease.

  
  

In other words, going from seed oils → tallow reverses that substitution — likely raising LDL and increasing CVD risk.

What About Inflammation?

Despite what you’ve heard online, multiple randomized trials show no increase in inflammation markers (like CRP or IL-6) when people eat diets higher in linoleic acid (the main omega-6 in seed oils).

• Johnson & Fritsche, 2012 (Systematic Review, 15 RCTs): Increasing dietary linoleic acid did not raise inflammatory biomarkers.

• Wu et al., 2017 (The Lancet): People with higher blood levels of linoleic acid had lower rates of type 2 diabetes — not higher.

  
  

Bottom line: omega-6 fats don’t cause inflammation in physiologic amounts. 

The real issue is ultra-processed foods, chips, fries, and packaged snacks, where these oils are often found alongside refined carbs, salt, and additives.

No one is saying to increase your intake of ultra-processed foods. But we also do not have to demonize seed oils just because they can be found in these foods. 

Seed oil manufacturing

Most seed oils in the supermarket are refined, meaning they’re extracted using heat and solvents like hexane, then filtered and deodorized.

That might sound scary, but typical hexane residues are well below FDA limits (0.2–0.6 parts per million), thousands of times lower than any toxic dose.

Modern oils are also non-hydrogenated,  meaning no trans fats. Trans fats were the real villains that once increased heart disease risk by 20-plus percent for every 2% of calories consumed.

What Really Matters: Quality, Quantity, and Context

Like most nutrition debates, this isn’t black and white.

• Seed oils used correctly (moderate amounts, not repeatedly heated) are safe and even beneficial when replacing saturated fat.

• Fried fast food and ultra-processed snacks,  even if cooked in seed oils,  are still unhealthy because of their calorie density, and hyperpalitability that makes them very easy to over consume.

• Cold-pressed or high-oleic oils (like canola, safflower, or sunflower) are excellent for everyday use and stable at high heat.

  
  

If you prefer animal fats for flavor or tradition, that’s fine, but don’t kid yourself that tallow is a health upgrade. It isn’t. 

Practical Takeaways

✅ Use olive oil, avocado oil, or high-oleic canola/safflower oil for cooking.

✅ Keep heat moderate and avoid reusing oil.

✅ Focus on whole-food sources of healthy fats — nuts, seeds, fish, avocado. 

✅ Limit saturated fats from butter, tallow, and coconut oil.

The Bottom Line

There’s no need to fear seed oils.

The real threat to our health isn’t a drizzle of canola oil, it’s the dominance of ultra-processed foods in the modern diet. 

So before tossing your cooking oil in favor of tallow, consider what the science,  not the social media feeds,  actually say.

Follow Jeff Krasno Podcast here or instagram here

For more evidence-based health insights subscribe to the Modrn Wellness podcast and follow @dr.marypardee on Instagram.

References

1. Hooper L, Martin N, Jimoh OF, Kirk C, Foster E, Abdelhamid AS. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database of Systematic Reviews. 2020;2020(8):CD011737. doi:10.1002/14651858.CD011737.pub3

2. Sacks FM, Lichtenstein AH, Wu JHY, et al. Dietary fats and cardiovascular disease: A Presidential Advisory from the American Heart Association. Circulation. 2017;136(3):e1–e23. doi:10.1161/CIR.0000000000000510

3. Zhang Y, Li S, Jiang Y, et al. Cooking oil/fat consumption and deaths from cardiometabolic diseases and other causes: prospective analysis of 521,120 individuals. BMC Medicine. 2021;19:92. doi:10.1186/s12916-021-01961-2

4. Johnson GH, Fritsche K. Effect of dietary linoleic acid on markers of inflammation in healthy persons: A systematic review of randomized controlled trials. Prostaglandins, Leukotrienes and Essential Fatty Acids. 2012;87(5):383–391. doi:10.1016/j.plefa.2012.08.001

5. Wu JHY, Marklund M, Imamura F, et al. Omega-6 fatty acid biomarkers and incident type 2 diabetes: a pooled analysis of cohort studies. The Lancet Diabetes & Endocrinology. 2017;5(12):965–974. doi:10.1016/S2213-8587(17)30307-8

6. Mozaffarian D, Katan MB, Ascherio A, Stampfer MJ, Willett WC. Trans fatty acids and cardiovascular disease. New England Journal of Medicine. 2006;354(15):1601–1613. doi:10.1056/NEJMra054035

7. Ramsden CE, Zamora D, Leelarthaepin B, et al. Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: Evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis. BMJ. 2013;346:e8707. doi:10.1136/bmj.e8707

8. Ramsden CE, Zamora D, Majchrzak-Hong S, et al. Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968–73). BMJ. 2016;353:i1246. doi:10.1136/bmj.i1246

9. American Heart Association Nutrition Committee. Dietary fats and cardiovascular health: summary of evidence. Circulation. 2021;144:e1–e21. doi:10.1161/CIR.0000000000001001

10. Guy H. Johnson, PhD, & Kevin Fritsche, PhD. Effect of Dietary Linoleic Acid on Markers of Inflammation in Healthy Persons: A Systematic Review of Randomized Controlled Trials. Prostaglandins Leukot Essent Fatty Acids. 2012;87(5):383–391. (duplicate confirmation of #4, retained here for completeness)

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