Someone threw a study at me recently.

I’d shared a clinical observation—that in my experience working as a care team health coach, I’ve seen removal of seed oils from the diet and an increase in animal fat reduce inflammatory markers on quarterly bloodwork. That’s not a hypothesis I pulled from a textbook; it’s something I’ve watched happen, patient after patient, over the course of hundreds of sessions.

The response? A link to a systematic review with a title long enough to make your eyes glaze over, and the implication that it settled the matter. The study was Fornari Laurindo et al., published in Frontiers in Nutrition in February 2025—“Evaluating the effects of seed oils on lipid profile, inflammatory and oxidative markers, and glycemic control of diabetic and dyslipidemic patients: a systematic review of clinical studies.” I’d encourage you to read it alongside this post so you can see exactly what I’m talking about.

Here’s the thing—I read the study. The whole thing. And what I found wasn’t a rebuttal of my clinical experience; it was a case study in why reading nutrition research carefully matters more than most people realize.

I’m not going to name the person or turn this into a debate about seed oils specifically (I’ve written about seed oils and inflammation elsewhere, and walked through a separate industry-funded review with the same kind of design problems). What I want to do instead is walk you through the questions I ask when someone hands me a study and says “this proves X.” Because these questions apply to every piece of nutrition research you’ll ever encounter—not just the ones you agree or disagree with.

Does the study actually test the claim being made?

This is the first question I ask, and it’s the one that catches people off guard the most.

The study I was handed was a systematic review of 11 clinical trials examining the effects of various seed oils on lipid profiles, inflammatory markers, and glycemic control. The person sharing it used it to argue that seed oils aren’t inflammatory and that they’re better than animal fats for metabolic health.

Here’s the problem: not a single one of the 11 included studies compared a seed oil to an animal fat. Not one. The comparisons were seed oil versus placebo, seed oil versus another seed oil, or seed oil paired with a drug or exercise program. The question “are seed oils better than animal fats?” was never asked—so the study can’t possibly answer it.

This happens more often than you’d think. A study gets cited for a conclusion it never actually tested. The title sounds relevant, the abstract mentions the right keywords, and most people stop there. In my experience, the gap between what a study actually examined and what someone claims it proves is where most bad arguments live.

What was actually being studied?

This one’s related, and it matters a lot in nutrition research because terminology can be slippery.

When people in the metabolic health space express concern about “seed oils,” they’re typically talking about industrially processed, high-linoleic-acid omega-6 oils—soybean oil, corn oil, cottonseed oil, and to some extent canola and sunflower. These are the oils that dominate processed food and have seen a massive increase in consumption over the past century.

The systematic review I read? It primarily examined sesame oil, pomegranate seed oil, perilla oil, flaxseed oil, and rice bran oil. Several of those are omega-3-dominant or contain unique fatty acids that behave very differently in the body. Perilla oil and flaxseed oil are actually celebrated because of their omega-3 content. Pomegranate seed oil contains punicic acid, a conjugated linolenic acid with its own distinct metabolic profile.

Lumping all of these together under the label “seed oils” and drawing a blanket conclusion is like saying “all medications work the same because they come in pill form.” The category is too broad to be meaningful, and the specific oils under debate weren’t well-represented in the data.

What did they actually measure—and what did they skip?

This is where I see a lot of nutrition research fall apart quietly.

The study I reviewed put “inflammatory markers” right in the title. You’d expect robust inflammatory data across all 11 trials. What I found was that most of the included studies didn’t measure inflammation at all. Only a handful assessed any inflammatory markers, and one of the studies that did—looking at pomegranate seed oil and TNF-α—found no significant change.

The single study that showed meaningful reductions in inflammatory markers (hs-CRP, PAI-1, TNF-α) combined perilla oil with a structured exercise program. So the inflammatory improvement could’ve been driven by the exercise, the oil, or the combination—there’s no way to isolate which one was doing the heavy lifting.

When a study puts a specific outcome in the title, I expect that outcome to be well-represented in the data. When it’s not, that tells me the title is doing more work than the research behind it.

How big was the study, and how long did it run?

Sample size and duration matter—a lot.

The studies in this review ranged from 36 to 143 participants, with most including fewer than 60 people. Intervention periods were 4 to 12 weeks. For context, chronic systemic inflammation—the kind that drives metabolic disease and shows up on bloodwork—often takes months to meaningfully shift. I see this in my own practice; quarterly labs are where the real trends become visible, not at the 4- or 8-week mark.

Small, short-term studies can identify signals worth investigating further, and I don’t want to dismiss them outright. What they can’t do is support sweeping dietary recommendations for entire populations. When someone cites a study with 38 participants over 60 days as evidence that a dietary pattern is safe or beneficial long-term, that’s a bigger leap than the data supports.

Were there confounding variables?

A confounding variable is anything other than the thing being studied that could explain the results. In nutrition research, confounders are everywhere—and they’re hard to control for.

In the review I read, several of the studies that showed positive outcomes had significant confounders built right into the design. One paired canola oil with a low-glycemic-load diet. Another added fiber alongside an oil blend. A third combined perilla oil with 30–60 minutes of daily exercise. In each case, the results were attributed to the oil, when the dietary or lifestyle changes happening alongside it could have been the real driver—or at least a major contributor.

This doesn’t mean the studies are worthless. It means their conclusions need to be held loosely. When I see a study where the intervention involves changing three things at once, I note the results, but I don’t treat them as proof that any single variable was responsible.

What kind of review is it?

Not all reviews are created equal, and this is something that trips up a lot of people—including practitioners.

The study in question was a narrative systematic review. That means the authors searched for relevant studies, summarized them in paragraph form, and drew qualitative conclusions. What it was not was a meta-analysis—a type of review that statistically pools data from multiple studies to calculate an overall effect size. Meta-analyses carry more weight because they quantify the evidence rather than just describing it.

A narrative review is essentially a structured opinion piece built on existing data. The quality of the included studies matters enormously, and the authors’ interpretation of those studies carries significant subjective weight. This isn’t a fatal flaw, but it does mean the conclusions should be read as “here’s what we think the evidence suggests” rather than “the evidence proves this.”

What do the authors themselves say about their limitations?

This is my favorite section to read in any paper, and it’s the one most people skip entirely.

The authors of this review openly acknowledged several significant limitations: short intervention periods that may not capture long-term effects, small sample sizes affecting statistical power, open-label designs introducing potential bias, incomplete biomarker assessment across studies, focus on specific populations limiting generalizability, and variability in dosing and duration making it difficult to compare results.

They literally used the phrase “results are sometimes inconsistent.”

When the people who conducted the review are telling you the evidence isn’t airtight, believe them. That level of honesty in a limitations section is actually a mark of good science—they’re being transparent about what their data can and can’t support. The problem isn’t the authors hedging; the problem is when someone ignores the hedging and uses the study as if it were definitive.

What’s missing from the conversation entirely?

Sometimes the most important thing about a study is what it doesn’t address.

This review didn’t examine the omega-6 to omega-3 fatty acid ratio—which is arguably the central mechanistic concern in the seed oil debate. When industrially processed seed oils displace omega-3 sources in the diet, the resulting imbalance drives pro-inflammatory eicosanoid production through the arachidonic acid pathway. That’s not a fringe theory; it’s well-established biochemistry. The fact that a review about seed oils and inflammation didn’t address this ratio is a significant gap.

The review also didn’t consider what happens to these oils under heat—the formation of oxidized lipids, aldehydes, and other toxic byproducts that are directly relevant to how people actually use cooking oils in real life. Most of the included studies used encapsulated supplements or oils added to food without high-heat exposure. That’s a very different scenario than the bottle of canola oil someone cooks with every night.

Bringing it all together

I’m not sharing any of this to attack a single study or to prove that my perspective on seed oils is the right one. I could be wrong about things—in my experience, so far, the clinical data I’ve personally observed tells a consistent story, but I don’t know what I don’t know.

What I do want is for anyone reading this—whether you’re a fellow coach, a clinician, or someone navigating your own health journey—to feel empowered to read research for yourself rather than taking someone else’s interpretation at face value.

Here’s the quick version of what I run through every time someone hands me a study:

  • Does the study actually test the specific claim being made with it?
  • What exactly was studied—and is the terminology precise or overly broad?
  • What outcomes were measured, and were there gaps in the data?
  • How many participants, and for how long?
  • Were there confounding variables that could explain the results?
  • What type of review or study design was used, and what are its inherent limitations?
  • What do the authors themselves say about the limitations?
  • What important questions were left unaddressed?

None of these questions require a science degree to ask. They just require a willingness to read past the title and the abstract—which, honestly, puts you ahead of most people who argue about nutrition on the internet.

I hope this gives someone some hope and direction. Research literacy isn’t about becoming a scientist; it’s about becoming a more informed participant in your own health decisions. And that’s something every single person is capable of.

Sources

  • Fornari Laurindo L, et al. “Evaluating the Effects of Seed Oils on Lipid Profile, Inflammatory and Oxidative Markers, and Glycemic Control of Diabetic and Dyslipidemic Patients: A Systematic Review of Clinical Studies.” Frontiers in Nutrition, 2025. 10.3389/fnut.2025.1502815

Rance Edwards is a National Board Certified Health and Wellness Coach (NBC-HWC) with over 2,000 clinical hours of experience, specializing in chronic disease management and lifestyle medicine.

Considering working with a health coach who takes the time to understand the research—and the person behind the symptoms? I offer a free discovery call with no pressure and no obligations. If we’re not the right fit, I’ll tell you—and I’ll do my best to point you toward someone who is. Book a Free Discovery Call

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