I’ve spent nearly two decades thinking about how the foods we eat affect our health. In 2007, I lost my father to Non-Hodgkin lymphoma. Six months later, my mother passed away from Chronic Lymphocytic Leukemia. Those experiences motivated me to understand why people get sick and what can be done about it. Since then, I’ve read countless studies on chronic diseases like cancer, diabetes, heart disease, and dementia, along with the mainstream coverage and interpretation of those studies.

These "diseases of modernity" as they're called, which only became prevalent in the last century, now affect 60% of American adults, and 42% have multiple chronic conditions [1]. Chronic diseases cause 75% of all deaths globally, including 1.7 million American deaths every year [2, 3]. On average, Americans spend roughly 17% of their lives managing chronic diseases, often at great personal and financial cost. Healthcare expenditures in the US, 90% of which are related to managing chronic disease, reached $4.9 trillion in 2023, twice what the entire world spends on defense [4, 5, 6]. Clearly, this is an urgent problem.

While chronic disease is complex and surely multifactorial, one dietary shift stands out since rates began soaring: the increased consumption of vegetable oils derived from seeds—commonly known as “seed oils.” These include soybean, canola, sunflower, safflower, cottonseed, grapeseed, rice bran, peanut, and corn oil. Together, they now account for about 20% of the calories Americans consume and represent the fastest growing subsector of global agriculture [7, 8]. Seed oils appear in everything from salad dressings and oat milk to fried chicken and french fries. They are cheap, accessible, and mostly tasteless, making them the go-to fats in restaurants and packaged foods.

Growing evidence suggests that excessive consumption of seed oils, particularly those high in omega-6 polyunsaturated fat (specifically, linoleic acid), may have deleterious effects on our health and play a significant role in the rise of chronic disease in the U.S. and around the world.

Meanwhile, the majority of media outlets—from The New York Times and The Atlantic to Women’s Health and Consumer Reports—paint seed oils as healthy components of a balanced diet and those who question their safety as conspiracy theorists, science-deniers, or ignorant social media influencers.

While these pro-seed-oil articles may sound logical and convincing on the surface, they are significantly flawed, misleading, or outright wrong upon closer examination.

‍Below are the 10 most common flaws in mainstream coverage of the seed oil debate:

Flaw #1: Ignoring conflicts of interest
Flaw #2: Excluding diverse perspectives
Flaw #3: Focusing on more omega-3 instead of less omega-6
Flaw #4: Suggesting seed oils are healthy because omega-6 is "essential"
Flaw #5: Shifting blame to other aspects of our diet
Flaw #6: Claiming seed oils are perfectly safe, unless actually used for cooking
Flaw #7: Relying on biomarkers and observational studies
Flaw #8: Attributing cardiovascular death rate improvements to seed oils
Flaw #9: Branding all seed oil critics as conspiracy theorists
Flaw #10: Downplaying the significance of the seed oil debate all together

Flaw #1: Ignoring conflicts of interest

Media coverage often fails to highlight how industry funding and conflicts of interest may skew research and nutrition policies on seed oils, leaving readers unaware that much of the pro-seed-oil data may be shaped by corporate interests rather than objective science.

Conflicts of interest are a well-documented problem in nutrition research. When industries fund research that aligns with their economic interests, the resulting studies often, unsurprisingly, support their products. Historical precedents abound: the tobacco industry financed research downplaying the harms of smoking, while soda companies funded studies that cast doubt on the link between sugary drinks and poor health.

For example, a 2013 analysis of beverage studies found that, “those funded by Coca-Cola, PepsiCo, the American Beverage Association, and the sugar industry were five times more likely to find no link between sugary drinks and weight gain than studies whose authors reported no financial conflicts.”

Like tobacco and sugar, many key studies praising the health benefits of seed oils have been supported by organizations with a direct financial stake in the widespread consumption of these oils, such as the Soy Nutrition Institute Global, United Soybean Board, Corn Refiners of America, National Corn Growers Association, Canola Council of Canada, USA Canola Association, and German Union for the Promotion of Oil- and Protein Plants.

As reported by the Guardian, so-called expert scientists defending ultra-processed foods, which are typically rich in seed oils (along with refined flours and sugars), often have ties to the world’s largest manufacturers of those foods, such as Nestlé, Mondelēz, Coca-Cola, PepsiCo, Unilever and General Mills.

Conflicts of interest that affect guidance on oils and fats are nothing new. As told by Nina Teicholz PhD in The Big Fat Surprise:

“The 1961 AHA [American Heart Association] advice to limit saturated fat is arguably the single-most influential nutrition policy ever published, as it came to be adopted first by the U.S. government, as official policy for all Americans, in 1980, and then by governments around the world as well as the World Health Organization. It is worth noting that the AHA had a significant conflict of interest, since in 1948, it had received $1.7 million, or about $20 million in today's dollars, from Procter & Gamble (P&G), the makers of Crisco oil. This donation was transformative for the AHA, propelling what was a small group into a national organization; the P&G funds were the ‘bang of big bucks’ that ‘launched’ the group, according to the organization's own official history. Vegetable oils such as Crisco have reaped the benefits of this recommendation ever since, as Americans increased their consumption of these oils by nearly 90% from 1970 to 2014.”

Another historical example of industry involvement in nutrition science is the case of trans fats. Although research from as early as the 1950s linked artificial trans fats to heart disease, industry-backed scientists and lobbyists repeatedly undermined findings showing their harm.

In fact, as reported by Vox, scientists employed by Kraft and Procter & Gamble "would routinely unpick and cast doubt on the emerging science of trans fat's health harms, often in journal articles," going so far as to "finding ways of getting papers that were critical of trans fats reviewed negatively in the pre-publication academic peer review process." According to one of these scientists, "Protecting trans fats from the taint of negative scientific findings was our charge." Ultimately, it took several decades—and a barrage of lawsuits and independent evidence—before the FDA formally banned trans fats in 2015, revealing the powerful role industry can play in delaying and shaping nutrition policy.

This doesn’t mean every scientist who accepts corporate funding is corrupt or that industry-funded studies can never yield truthful results. But it does mean readers should approach industry-backed conclusions with caution.

Moreover, the chain of influence extends beyond studies: A 2022 study in Public Health Nutrition found that 95% of the 2020–2025 U.S. Dietary Guidelines committee members, which help shape national nutrition policy, had conflicts of interest with food and/or pharmaceutical industries.

The Dietary Guidelines for Americans, which are finalized by the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services, have a far-reaching impact, from what kids are fed in public schools and hospitals to what we feed prisoners and the military. In addition, the dietary guidelines act as the government’s official dietary recommendations, and thus any organization wishing to be in alignment with government recommendations, whether it’s universities seeking federal funding or policy makers seeking governmental positions, have an incentive to promote whatever the dietary guidelines promote, which in the case of cooking oil, is guzzling ever more soybean, canola, and corn oil.

Although our consumption of soybean oil in particular, which is synonymous with the term “vegetable oil” in the US, has increased more than 1,000-fold since the beginning of the last century, and like all seed oils is nearly devoid of nutrients, the 2015-2020 dietary guidelines claimed that about three-quarters of Americans were below the recommended intake of these oils and the 2020-2025 dietary guidelines categorized vegetable oil as a “nutrient-dense” food:

The involvement of the USDA in finalizing dietary guidelines also poses a potential conflict. The USDA’s mandate includes “stabilizing or improving domestic farm income,” which naturally supports the success of major U.S. crops such as soy, canola, corn, cotton, rice, peanuts, and sunflower—the very ingredients behind the most prevalent seed oils (soybean oil, canola oil, corn oil, cottonseed oil, rice bran oil, peanut oil, and sunflower oil). Balancing domestic agricultural interests with objective nutritional advice becomes challenging when the same entity is responsible for both.

While financial ties and motives are most tangible, conflicts of interest don’t just revolve around money. Professional and cultural pressures also come into play. Health professionals who question prevailing recommendations risk marginalization and prevailing biases shape which questions are asked, how results are interpreted, and which conclusions are highlighted [9].

By ignoring these entanglements, mainstream coverage leaves audiences unaware of the incentives shaping nutritional advice. Even registered dietitians, who are often cited and quoted as experts in the seed oil debate, are educated solely by a single organization with significant conflicts of interest and ties to food companies, which we’ll explore in the next section.

Flaw #2: Excluding diverse perspectives

Mainstream reporting tends to rely on the same few experts and registered dietitians influenced by a single accrediting body. This limited perspective overlooks researchers who specifically study seed oil harms, narrowing the debate to "one side of the story" and preventing a balanced understanding of the issue.

Many journalists claim to value diverse perspectives, yet their coverage of seed oil controversies often falls short of this standard. 

Articles exploring the potential harms of seed oils frequently feature the same limited circle of experts who have doggedly supported seed oils for years or decades—most notably figures like epidemiologist Walter Willett and Guy Crosby from Harvard and cardiologist Dariush Mozaffarian from Tufts (the same organization that encourages eating Frosted Mini-Wheats and Honey Nut Cheerios over other more nutritionally-dense foods).

When seeking a credible and supposedly neutral third-party opinion, reporters often turn to registered dietitians, also known as RDs, nutritionists, or simply dietitians. While dietitians are certainly knowledgeable professionals dedicated to helping people eat well, it’s important to understand their educational environment.

The only accrediting body for all dietitians’ training programs is the Academy of Nutrition and Dietetics (AND), which means all registered dietitians undergo a standardized curriculum overseen by the same private organization. Such uniformity in training can unintentionally limit the range of viewpoints presented. 

Complicating matters further, the AND has been cited as having significant conflicts of interest with certain food companies and allowing those companies to provide continuing education courses to its dietitians, as published in Public Health Nutrition and reported by the Washington Post.

This doesn’t mean dietitians are bad actors; it simply means they, like everyone else, are influenced by the information and guidance they are provided. When the accrediting body itself has industry ties, recommendations often reflect those interests, making it more likely that dietitians will consistently advise the consumption of seed oils in line with AND’s recommendations.

While university nutrition chairs and registered dietitians may be perceived to be more credible interviewees and may make more confident and assertive statements about the healthfulness of seed oils, they are operating within a system influenced by outdated science, financial incentives, and institutional biases. It is not doing justice to the seed oil debate to only interview them, and exclude the numerous individuals, scientists, physicians, toxicologists, and researchers who have extensively studied and written about the history and harms of seed oils, including Ameer Taha, PhD, Christopher Ramsden, MD, PhD, Nina Teicholz, PhD, Joseph Hibbeln, MD, Paul Saladino, MD, Catherine Shanahan, MD, Tucker Goodrich, Chris Knobbe, MD, and others.

An exception is a Business Insider article by Hilary Brueck, who included interviews with a range of experts—including critics of seed oils–and as a result reported a much more nuanced view of the complex topic of seed oils. Such diverse coverage is rare.

Recognizing the influences that shape our nutrition policy can help us move beyond the narrow range of voices currently dominating the conversation and toward a more informed, multifaceted discussion about the role of seed oils in our diets.

Flaw #3: Focusing on more omega-3 instead of less omega-6

While most experts agree on the importance of a balanced intake between omega-3 fat and the omega-6 fat found in seed oils and other foods, proponents of seed oils claim that any imbalance should be fixed by increasing omega-3 intake, rather than reducing omega-6. However, this advice requires consuming impractically large amounts of omega-3-rich foods, to the tune of 10-20 salmon filets per day!

Critics of seed oils often (correctly) point out their extraordinarily high omega-6 content, unmatched by any other food. While most foods contain only milligrams of omega-6 per serving, most seed oils contain several grams per serving. 

For example, common foods like black beans, ground beef, milk, broccoli, tuna, chicken breast, oatmeal, peach, shredded wheat, rice, and corn all contain a few hundred milligrams or less of omega-6 per serving, while one serving (tablespoon) of common seed oils like canola, soybean, grapeseed, or safflower oil contains between 3-11 grams of omega-6.

Given the average American consumes multiple tablespoons of seed oils every day, often unknowingly, in the form of restaurant meals, fried foods, mayonnaises, sauces, plant-based milks and meats, crackers, and bread, the total amount of omega-6 in our diets has increased considerably, from about 2.79% of calories (~9.5 grams per day) in 1909 to 7.21% of calories (~24.6 grams per day in 1999 [10, 11]. Today, given our increased consumption of seed oils in the last 25 years, that number is likely much higher.

This abundance of omega-6 from seed oils can skew the overall ratio of omega-6 to omega-3 fats in our diets. Maintaining an optimal omega-6 to omega-3 ratio has shown to be important; an imbalance can promote inflammation and may be linked to various chronic health conditions [12].

While omega-6 fats are found predominantly in seed oils, omega-3 fats like DHA and EPA are found primarily in algae and fatty fish, such as salmon, mackerel, herring, and sardines. Omega-3’s less bioavailable form, ALA, is found in certain nuts and seeds, such as flaxseeds, chia seeds, and walnuts. Part of the reason the balance between omega-6 and omega-3 is so important is because most Americans get their omega-3’s in the form of ALA, and excess consumption of omega-6 “competes” with and blocks the pathways in our bodies that allow the conversion of ALA to the more usable forms of DHA and EPA.

The more omega-6 we consume, the less omega-3 our bodies have available. For most of human evolution, our omega-6 to omega-3 ratio was about 1:1; today, largely because of our increased consumption of high-omega-6 seed oils, that ratio is between 10:1 to 20:1, and as high as 50:1 in some parts of the world [13, 14].

Even proponents of seed oils acknowledge that striking a balance between these fats is important—yet their primary solution tends to be encouraging people to eat more omega-3, rather than questioning whether we should consume so much omega-6 in the first place.

To understand the practicality of this advice to focus on more omega-3 instead of less omega-6, consider how much omega-3 would be required to balance the levels of omega-6 the American Heart Association (AHA) and other organizations consider acceptable. According to Harvard Health, “The AHA, along with the Institute of Medicine, recommends getting 5% to 10% of your daily calories from omega-6 fats. For someone who usually takes in 2,000 calories a day, that translates into 11 to 22 grams” [15].

Achieving a balanced ratio would mean consuming a similar amount of omega-3—up to 22 grams daily. To put that number into perspective, one serving of salmon (a 3.5 oz filet) provides about 2.15 grams of omega-3 [16].

Therefore, based on advice from the American Heart Association, Harvard Health, and other organizations, having a balanced omega-6 to omega-3 ratio would require eating the equivalent of 10 salmon filets every single day, a clearly unrealistic amount.

While the example above assumes 2,000 total daily calories, the Dietary Guidelines for Americans recommend up to 3,200 daily calories for men, which, based on the AHA’s recommendation of up to 10% of calories from omega-6 fats, translates to up to 36 grams of omega-6 per day. Balancing that amount with omega-3 fats would mean trying to eat the equivalent of 17 salmon filets a day—an even more impractical scenario. And since the average American consumes well over 3,200 daily calories and often exceeds 10% of calories from omega-6 due to consuming seed oils, the amount of omega-3 needed to “be in balance” becomes even greater.

Consider how easy it is to surpass 10% of calories from omega-6. Given just one tablespoon of soybean oil, safflower oil, or grapeseed oils contains up to 11 grams of omega-6, a few tablespoons of these seed oils, combined with other foods, can push omega-6 intake far beyond the recommended upper limit. This can happen even when following dietary guidelines that are meant to be “healthy” and lower in saturated fats, as these guidelines often suggest replacing saturated fats with seed oils.

In practice, simply advising people to increase their omega-3 intake to compensate for high omega-6 levels is neither realistic nor efficient. It would be simpler and more achievable to limit omega-6-rich seed oils rather than expecting the average person to consume enormous quantities of omega-3-rich foods every day.

Flaw #4: Suggesting seed oils are healthy because omega-6 is "essential"

Using the word "essential" to describe the omega-6 fat in seed oils (linoleic acid), while technically accurate, may mislead readers into thinking that seed oils themselves are essential, highly beneficial, or inherently healthful in large amounts, when in reality, the body needs only tiny amounts of omega-6, and excessive omega-6 has known harms.

Many mainstream sources highlight that omega-6 fat, in particular linoleic acid, is "essential" and necessary for various bodily functions. While this is technically true—our bodies do need a small amount of linoleic acid from our diets—it can also create a misleading impression. Calling something “essential” in the nutritional sense simply means the body cannot synthesize it and requires a minimal daily intake to avoid deficiency. It does not imply that more is always better, or that a food rich in that nutrient is inherently “healthful.”

This distinction is important because it’s easy to confuse "essential" with "beneficial at any level," as demonstrated by the most basic principle of toxicology: "the dose makes the poison."

For linoleic acid, the minimum dietary requirement is extremely low. Roughly 1 gram per day on a 2,000-calorie diet — just 0.5% of calories — is likely enough to prevent deficiency [17].

Even eating a diet focused on the foods lowest in linoleic acid, from black beans and bananas to ground beef and cheese, will result in over 1 gram per day of the fat, making deficiency impossible unless on an artificial, completely non-fat diet.

While emphasizing the essentiality of omega-6 linoleic acid sounds like a strong argument in support of high-linoleic seed oils, it is actually an irrelevant and misleading point.

Flaw #5: Claiming seed oils are perfectly safe, unless actually used for cooking

Most mainstream reporting on seed oils acknowledges that heating or frying them produces harmful compounds, which are avoided with more stable fats, but then blames the harms of heated seed oils on the cooking method rather than the choice of cooking oil. Since most soybean oil, corn oil, and canola oil is consumed after being heated or fried, rather than being drizzled, it is not honest or logical to present seed oils as harmless when the primary way of consuming them inherently involves creating dangerous compounds.

Proponents of seed oils often acknowledge that heat damages these oils in particular due to their high content of polyunsaturated fats, producing harmful and even carcinogenic byproducts. They note, for instance, that repeatedly heating seed oils—common in practices like deep-frying—can create toxic compounds associated with cardiovascular disease, metabolic disorders, and cancer. 

Yet, in the same breath, these same voices assert that seed oils themselves are not the issue. In doing so, they minimize the importance of choosing more stable oils for deep frying, claiming that doing so “won’t negate the health impacts of eating deep-fried foods.” This line of reasoning is illogical and seems to dismiss seed oils’ role in forming harmful compounds once heated, effectively sidestepping the core issue.

Most seed oils are not consumed as cold drizzles over salads; their primary use—especially in restaurants, where most seed oils are consumed—is cooking, often at high temperatures and frequently through deep-frying. To say seed oils are “perfectly fine” provided you don’t heat them is to ignore the reality of how they are actually employed in our food system. This is akin to saying, “Added sugars are fine, as long as you don’t consume them in soft drinks or desserts.” Both statements sidestep the main point: these products are overwhelmingly consumed in exactly the manner that is said to be problematic.

Research shows that cooking with seed oils, rather than oils or fats lower in polyunsaturated fats, results in more harmful oxidation products like 4-HNE and other toxic aldehydes, which are derived only from omega-6 polyunsaturated fat, and are linked to serious health issues [18, 19].

If switching to more stable fats can reduce the formation of these toxic compounds, that clearly suggests a health benefit. Ignoring this potential improvement—by shrugging off the importance of the type of oil used—undermines the credibility of the argument that “it’s not the oil itself.”

By downplaying the inherent vulnerability of seed oils to heat and oxidation, responsibility is subtly shifted to the consumer’s habits, implying that if you only used these oils in a perfectly controlled, low-heat environment, they would pose no issue. Yet in reality, home cooks, restaurants, and food manufacturers regularly engage in the very cooking practices that cause these oils to degrade. 

If the primary route of consumption inherently involves creating dangerous compounds, then it’s not honest or logical to present seed oils as harmless.

Flaw #6: Shifting blame to other aspects of our diet, such as saturated fat and sodium

Mainstream outlets often point to refined carbohydrates, sodium, saturated fat, or simply eating too much as culprits in chronic disease while ignoring that these factors haven’t risen in tandem with disease rates. Meanwhile, seed oil consumption has skyrocketed, warranting their inclusion as a key suspect.

Over the past few decades, the United States has experienced dramatic increases in rates of obesity, diabetes, cancer, and other chronic diseases. Since the year 2000, obesity rates have increased by 39%, diabetes rates have more than doubled, cancer rates have gone up by 7%, and chronic disease rates have climbed by 32% [20].

Mainstream coverage often points to saturated fat, sodium, sugar, refined carbohydrates, and simply eating too much as the primary culprits. At first glance, this seems intuitive — after all, these factors are regularly attributed to poor health outcomes in mainstream reporting of chronic disease.

But when we look at the data more closely, a puzzling pattern emerges: since the year 2000, according to USDA reports on food and nutrient consumption, while American intake of vegetable oils (seed oils) have increased considerably, our intake of saturated fat, sodium, sugar, and grains (which become refined carbohydrates) have not increased in line with increasing rates of chronic disease, nor has total caloric consumption, as seen in the charts below.

While meat consumption per capita has modestly increased, the entirety of that increase has come from poultry (chicken), which is leaner and lower in saturated fat than beef, lamb, and pork, resulting in a net decrease in saturated fat consumption over the last couple decades:

While we are eating more today than in the mid 1900s, total caloric consumption has remained relatively flat over the last couple decades:

We are not consuming any more calories, saturated fat, sodium, sugar, or carbohydrates today compared to 25 years ago; yet during that same time, chronic disease and obesity rates have continued to rise:

If there are aspects of our diets that have remained largely unchanged over the past several decades, it may be unwise to focus on them exclusively as the dietary evils responsible for the growing chronic disease epidemic.

On the other hand, if our consumption of certain foods, such as seed oils, have increased in line with increasing rates of chronic disease and obesity, while the association is certainly not causative, those foods should at least be candidates for further consideration and extensive research.

This doesn’t mean these other dietary factors, such as the excess consumption of added sugars and refined carbohydrates, don’t play a role, even a significant role, in one or more chronic diseases, but to dismiss seed oils out of hand for the sake of focusing more exclusively on these other factors is doing the field of nutrition journalism a disservice. To put blinders on and only focus on aspects of our diet that have not changed in decades, while chronic disease rates continue to rise, may risk missing other, potentially more significant dietary drivers of chronic disease.

Flaw #7: Relying on biomarkers and observational studies

Headlines often trumpet correlations between seed oil intake and improved biomarkers or lower disease risk based on observational studies. However, these correlations don’t confirm causation and can easily mislead readers into thinking the evidence in favor of seed oils is the gold standard.

At first glance, the statements above seem straightforward: seed oils, rich in linoleic acid, correlate with lower LDL cholesterol and a decreased risk of certain chronic diseases. This narrative sounds reassuring. But when we look closer, we see a flawed reliance on biomarkers and observational studies that do not necessarily prove that seed oils are beneficial—or even harmless—over the long term.

Biomarkers refer to the measures that show up on your blood tests, like LDL cholesterol or inflammation markers. The problem is that these short-term indicators don’t tell the whole story. Over time, our understanding of what constitutes a “good” or “bad” biomarker continually evolves.

For example, decades ago, total cholesterol was considered the prime culprit in heart disease, leading public health guidelines to demonize fats based on their ability to raise cholesterol levels. Later, however, it was discovered that there are different types of cholesterol – "good" HDL cholesterol and "bad" LDL cholesterol. Today, we know that focusing solely on LDL cholesterol is oversimplified; there are subtypes of LDL and other risk factors that matter more for long-term health outcomes.

Biomarkers are typically used when actual health outcomes, like death, are unavailable. While biomarkers can be unreliable and misleading, there’s no arguing about whether someone dies.

Simply improving a particular biomarker does not necessarily translate into reduced disease or longer lives, and in some cases, can have the opposite effect. For example, the Minnesota Coronary Experiment, a five-year double blind randomized controlled trial published in 2016, found that participants who increased their consumption of seed oils lowered their LDL cholesterol. However, among older participants, the group with the lowest LDL cholesterol also died the most of heart disease.

If the study were only measuring LDL cholesterol, the conclusion may be that seed oils prevent heart disease, but by measuring actual rates of heart disease and death, the opposite conclusion was made. 

As research progresses, what once seemed like a reliable marker of good health may turn out to be incomplete or even misleading. Without evidence from well-designed studies measuring real-world outcomes, it’s risky to draw strong conclusions from these snapshot measures.

In addition to the inherent reliance on correlation between biomarkers and health outcomes, nearly all of the studies cited by media outlets are observational studies, meaning they ask people what they ate over a given time period and then correlate those dietary patterns to various outcomes, which may result in interesting associations, but cannot establish cause and effect.

As I’ve written about previously, and as described by others like Nate Silver and Dr. Georgia Ede, observational studies in nutrition are inherently unreliable, and prove only correlation (not causation) due to inaccurate participant reporting and unavoidable confounding variables.

A pivotal 2005 essay by professor John Ioannidis at the Stanford School of Medicine states, "for many current scientific fields, claimed research findings may often be simply accurate measures of the prevailing bias," and continues, "even well-powered epidemiological [observational] studies may have only a one in five chance being true."

A 2011 paper in the Journal of the Royal Statistical Society puts it more bluntly: "Any claim coming from an observational study is most likely to be wrong."

In the field of nutrition, observational research relies heavily on self-reported dietary habits and the subjective memories of study participants, via food frequency questionnaires, which have been shown time and again to be inaccurate and unreliable. A 2015 paper in the International Journal of Obesity writes that self-reported data on diet are so poor that "they no longer have a justifiable place in scientific research."

In a 2008 study on self-reported data in nutrition research, participants were asked to report their intake of fruits and vegetables. Before completing the questionnaire, half of the participants received a letter describing the benefits of fruits and vegetables. Those who received the letter reported 40% higher intakes of fruits and vegetables, not because they actually ate more than participants who didn’t receive the educational letter, but simply because they were exposed to and influenced by the prevailing bias that vegetables and fruits are healthy.

Therefore, people who report eating more canola oil (and less butter and lard) might also claim to eat more vegetables, exercise regularly, and avoid smoking. These healthier behaviors, rather than the seed oils themselves, could be driving better health outcomes. Such confounding factors make it impossible to isolate seed oils as the primary cause of any observed benefit, yet this type of research forms the foundation of most observational studies, which inform much of our public health policies, including recommendations to consume more seed oils.

Observational studies can seem quite impressive, and therefore be influential, because their size and duration are limited only by how many participants fill out a questionnaire each year. A study of "400,000 people over a 24-year period" sounds robust; however, if the observational nature of the study is inherently flawed due to bias and confounding, the findings are unreliable regardless of the study’s size or length.

Reporting on the results of studies that rely on biomarkers or observation, rather than health outcomes and controlled trials, without proper context or more rigorous validation, risks oversimplifying complex nutrition science. Worse, many of the studies cited in mainstream coverage of seed oils rely on the combination of both biomarkers and observational studies–for example, an observational study that finds seed oil consumption is associated with lower LDL-cholesterol levels (biomarker) will result in media coverage that suggest seed oils prevent heart disease (health outcome).

It’s essential to recognize the limitations of these approaches before drawing strong conclusions about the health effects of seed oils.

Flaw #8: Attributing cardiovascular death rate improvements to seed oils

Some sources suggest that the introduction of seed oils is responsible for historical declines in heart disease deaths, ignoring numerous other factors like reduced smoking and better medical care.

By pointing to a correlation between increasing vegetable oil (seed oils) consumption and declining heart disease deaths, some articles imply that these oils deserve the credit for improved heart health. This interpretation oversimplifies a multifaceted public health story by attributing a decades-long decline in cardiovascular mortality to a single dietary factor.

In reality, cardiovascular health improved thanks to a complex interplay of factors: declining smoking rates, better medical treatments, advances in emergency care, and increased public awareness of heart health [21, 22]. To credit seed oils alone is to rewrite history, ignoring the multifaceted nature of public health progress.

Following the U.S. Surgeon General’s 1964 report linking cigarettes to serious health risks, smoking rates fell sharply. This single change lowered systemic inflammation, reduced oxidative stress, and decreased the burden of arterial damage—factors directly tied to heart disease risk. The reduction in smoking alone provided a substantial boost to overall cardiovascular health, independent of dietary fat intake.

Simultaneously, treatment for heart attacks improved dramatically. In the 1960s, a heart attack carried a 20-30% risk of death; by the 2000s, improved medications, surgical interventions, and post-event management lowered that risk to 5-10% [23]. This improvement in acute care and ongoing therapy for heart disease patients further reduced cardiovascular mortality, regardless of dietary fat composition.

During the 1960s when heart disease rates began to decline, Americans made numerous adjustments to their eating and living habits as a result of greater awareness of cardiovascular risk factors. While seed oils represented one of these adjustments, singling them out as the linchpin in public health gains neglects the complexity of the shifts that took place.

Flaw #9: Branding all seed oil critics as conspiracy theorists

Media coverage often casts the seed oil debate as a battle between rational experts and fringe social media influencers, thereby marginalizing serious scientific health concerns about seed oils and discouraging readers from engaging with the actual evidence.

Rather than engaging directly with scientific findings questioning our unprecedented consumption of seed oils, many media outlets frame the debate as a clash between credible scientists and fringe, often politically-charged influencers. By doing so, they only highlight some of the most controversial, extreme voices critical of seed oils and then present the pro-seed-oil stance as the expert consensus.

This tactic, a type of ad hominem attack, shifts attention away from substantive data, including randomized controlled trials and meta-analyses, and focuses on personalities and perceived credibility. It becomes easier to dismiss the entire anti-seed-oil viewpoint as one of “wellness influencers and conspiracy theory peddlers,” as portrayed in the Rolling Stone article above, when it appears affiliated with polarizing ideologies, rather than acknowledging the thoughtful critiques put forth by numerous scientists and health professionals. When portrayed in this way, the issue is cast as an open-and-shut case, leaving little room for nuanced discussion.

To “prove” the delusion of individuals concerned about seed oils, in addition to highlighting only the most controversial seed oil detractors, some journalists also suggest that we’ve been eating these oils for thousands of years, thereby discrediting the argument that they are a new, significant, and potentially concerning addition to the human diet. 

For example, as put forward by Eater in an article titled, “Why Are People So Freaked Out About Seed Oils?” (bolding mine):

“The panic over seed oils has escalated as many have taken seed oil-linked health concerns and projected onto them the idea that this is not how we’re “supposed” to eat. The solution, the thinking goes, lies in an imagined past where foods were not processed, or even regulated in any way. (Though it’s important to note seed oils aren’t new — Native Americans in modern day Arizona and New Mexico were crushing sunflower seeds for oil in 3000 BCE.) This is perhaps why these theories have found ground in the more right-wing reactionary corners of the internet.”

What this article fails to mention is that the rare historical use of seed oils by Native Americans was for skin and hair, not for eating. A journal article on the subject explains that sunflower oil was used by Native Americans for “sunscreen and hair decoration,” while another research article on the history of sunflower describes how “generations of the Iroquoian tribes have used oil of sunflower achenes for dressing their hair at tribal ceremonies” [24, 25].

In other words, at least according to the actual research, any historical use of oil from sunflowers was primarily or only for non-food purposes, such as for sunscreen and hair decoration.

In another article, titled “What's the Deal with Seed Oils?" from a journalist who writes for the Wall Street Journal, Businessweek, and The New York Times (bolding mine):

“lately the clamor against seed oils has gotten louder. Among their high-profile detractors today are RFK Jr., who has said that seed oils are poisoning us; Joe Rogan, who mistakenly believes that until recently humans didn’t eat oils from plants (in fact, we’ve been pressing seeds for oil since at least 400 AD); the Liver King, a fitness influencer whose He-Man physique was recently revealed to come from devouring steroids, not organ meats; and an anonymous figure named the Seed Oil Scout who apparently became radicalized after personally experiencing the gut-health benefits of a seed-oil-free life.”

The reference above to “pressing seeds for oil” since at least 400 AD links to a journal article that has no mention of humans actually eating those oils: “The first recorded usage of vegetable oils and animal fats dates back to Mesopotamia (7,000 BC) and ancient Egypt (5,000 BC). They were used for cosmetic applications such as body oils and lotions. Around 2,000 BC, these populations started producing scented oils for mummification and for personal hygiene, healthcare, and cosmetics. […] Between 400 and 1,000 AD, despite the world being preoccupied by the Dark Ages, in some part of Europe and in China, Japan, and North America, great advances were made in the usage of oils and fats especially applied to medicine and alchemy” [25].

While this journal article expands on the historical use of seed oils—beyond skin and hair—to mummification, medicine, and alchemy, there is no evidence offered that humans actually ate oils pressed from seeds until recently.

Even if evidence is found that some Ancient Egyptians or some Native Americans in some tribes at some times of the year ate minuscule amounts of seed oils, those are simply the exceptions that prove the rule: for the huge majority of our evolutionary history, we did not consume seed oils in any meaningful quantities. 

Leading readers to believe that the anti-seed oil viewpoint is supported only by reactionary conspiracy theorists who are misinformed on the historical consumption of oils pressed from seeds, is not only wrong, but also does nothing to further productive discourse.

Flaw #10: Downplaying the significance of the seed oil debate all together

Many articles end by trivializing concerns about seed oils, arguing that since french fries and ultraprocessed foods aren’t healthy anyway, the oil used doesn’t matter. This dismissiveness ignores the fact that not only do seed oils permeate many seemingly healthy foods, but also that healthier oils may make junk food less unhealthy, which is sorely needed given the declining state of our health.

Many mainstream media outlets, after exploring the debate over seed oils, wrap up their coverage by essentially minimizing its importance. The argument goes something like this: french fries, chicken nuggets, and other deep-fried foods will never be truly “healthy” anyway, and since ultraprocessed foods are detrimental for a host of reasons, does it really matter which oil they’re cooked in?

This line of reasoning glosses over the core issue. Yes, avoiding ultraprocessed foods is widely agreed upon. Yes, french fries and fried chicken are not the pinnacle of human nutrition. But these acknowledgments don’t address the root concern behind the seed oil debate: the sheer ubiquity of these oils in our food supply and the mounting evidence suggesting their potential impact on long-term health.

By focusing on the idea that "french fries aren’t healthy anyway," these concluding remarks shift attention away from the underlying problems: that fried and ultraprocessed foods, which billions of people across the world eat every day, can be less unhealthy with more healthful oils, and that many everyday foods, not just overt junk food, are now prepared with seed oils. These oils are found in salad dressings, sauces, cereals, crackers, plant-based milks and meats, and numerous other staples that people might consider relatively wholesome. Brushing off the debate as insignificant because "avoiding processed foods is good advice anyway" sidesteps the question of whether we should reevaluate seed oils as the default fat in a wide range of products, not just the most obviously unhealthy ones.

Moreover, mainstream coverage often assumes there's an easy "choice" in whether to eat seed oils—just avoid foods that contain them or cook with something else. Yet for many Americans, that choice does not exist in any meaningful way. Seed oils are ubiquitous in nearly all restaurant meals and packaged foods, which millions of Americans rely on for sustenance, and in many institutional settings such as children’s school lunches, hospital food, and meals provided to the military and in prisons. People in these environments frequently don’t have the privilege or the means to request a different oil, let alone cook their own meals at home. Mainstream outlets ignore this reality that seed oils, including as part of ultraprocessed or fried foods, are an unavoidable part of many people’s diets—especially for those with fewer resources or less autonomy.

In short, advice to simply eat less junk food and not worry about seed oils is incomplete. It not only ignores the fact that the majority of Americans will continue eating large amounts of ultraprocessed and fried foods, either out of choice or out of necessity, but also sidesteps the central debate around the nature and consequences of widely consuming oils high in omega-6 fats.

If we genuinely want to have a positive impact on health outcomes in the U.S., we must acknowledge that even if we improve other aspects of our diets, the types of oils we consume still matters.