Seed oils are industrially extracted fats produced from soybeans, corn, canola, cottonseed, sunflower seeds, and safflower seeds using hexane, a petroleum solvent, followed by high-heat deodorization to remove the rancid smell the process produces. They did not exist in the human diet before the 20th century. Traditional fats, including butter, lard, tallow, and cold-pressed olive oil, are produced through fundamentally different processes.

Why does the AHA recommend vegetable oils?

The AHA's dietary recommendations favoring vegetable oils date to the period following its 1948 founding donation from Procter and Gamble, the maker of Crisco. The two largest controlled trials of the specific recommendation, the Minnesota Coronary Experiment and Sydney Diet Heart Study, were buried for decades. Both found that replacing saturated fat with vegetable oil increased cardiovascular mortality. Neither was cited in the AHA's 2017 dietary fat advisory.

What should I cook with instead of seed oils?

Butter or ghee from grass-fed animals for most cooking. Coconut oil for higher-heat applications. Extra virgin olive oil for low-heat cooking and dressings. Tallow or lard from pasture-raised animals for high-heat cooking. These are the fats that existed in the human diet before the chronic disease epidemic of the latter 20th century.

What happened with trans fats and the AHA?

The AHA endorsed partially hydrogenated vegetable oils (trans fats) as heart-healthy alternatives to saturated fat for approximately five decades following P&G's 1948 founding donation. Research documented substantial cardiovascular harm from trans fat consumption. The FDA removed GRAS status from partially hydrogenated oils in 2015, banning them from the US food supply as of 2018.

Is olive oil a seed oil?

No. Olive oil is pressed from the flesh of the olive fruit without solvent extraction. Extra virgin olive oil is cold-pressed and retains polyphenols associated with cardiovascular protection in the PREDIMED trial. Olive oil is primarily monounsaturated fat, making it more chemically stable at heat than polyunsaturated seed oils and producing fewer toxic degradation compounds at cooking temperatures.

The Oils in Your Kitchen Are the Most Recent Addition to the Human Diet. Here Is Who Funded the Research That Called Them Heart-Healthy.

The oils in your kitchen that your physician approves, your grocery store promotes, and the American Heart Association labels as heart-healthy did not exist in the human diet before the 20th century. Canola oil, soybean oil, corn oil, cottonseed oil, sunflower oil, and safflower oil are industrial products manufactured through petroleum solvent extraction and high-heat deodorization. The organization that recommends them was established as a national institution with a $1.74 million donation from Procter and Gamble, the company that made Crisco.

The AHA's dietary recommendations have consistently aligned with the commercial interests of the vegetable oil industry since 1948. The two largest controlled trials ever conducted on the specific recommendation to replace saturated fat with vegetable oil were buried for decades. When NIH researcher Christopher Ramsden published in the BMJ in 2013 and 2016, both studies showed that replacing saturated fat with seed oils lowered cholesterol but increased cardiovascular mortality. The AHA's 2017 Presidential Advisory on dietary fats did not cite either study.

What Seed Oils Are and How They Are Made

Soybeans, corn, rapeseeds, cottonseed, sunflower seeds, and safflower seeds do not produce edible oil through simple pressing. The oil content must be extracted through industrial methods.

The primary industrial extraction method uses hexane, a petroleum-derived hydrocarbon solvent. Seeds are processed with hexane, which dissolves the oil from the seed material. The resulting oil-hexane mixture is separated, and the hexane is removed by evaporation. The crude extracted oil is dark and cloudy, and carries a strong, unpleasant odor from oxidation that occurs during industrial-scale extraction.

The crude oil then undergoes refining. Degumming removes phospholipids. Neutralization with caustic soda removes free fatty acids. Bleaching with clay removes color compounds. Finally, deodorization exposes the oil to steam at temperatures between 450 and 500 degrees Fahrenheit to strip volatile compounds responsible for the rancid odor. The product that emerges from this process is clear, odorless, shelf-stable, and visually indistinguishable from a natural oil.

No traditional culture in human history produced oils through hexane extraction and high-heat deodorization. Cold-pressed olive oil, cold-pressed sesame oil, butter churned from cream, and lard rendered from pork fat are fundamentally different products from what the industrial seed oil process produces. The human body has existed throughout its evolutionary history without these industrial fats. They entered the American diet in commercially significant quantities only in the 20th century, and they did so accompanied by institutional recommendations from an organization whose founding donor made the original version.

(Evidence level: 5. The industrial production process is documented in food science and FDA-regulated manufacturing practice. Hexane extraction is disclosed in industry and regulatory documentation.)

The Linoleic Acid Shift: One Century, One Dietary Change

Linoleic acid is an omega-6 polyunsaturated fatty acid. It is the primary fatty acid in most seed oils: approximately 50-60% of soybean oil, 58% of corn oil, 73% of sunflower oil, and 75% of safflower oil.

Joseph Hibbeln and Christopher Ramsden at the National Institutes of Health published a quantitative analysis in the American Journal of Clinical Nutrition in 2011 documenting changes in linoleic acid intake in the American diet over the 20th century. Linoleic acid increased from approximately 2% of total caloric intake in 1900 to approximately 8% by the early 2000s. A fourfold increase in one century. The omega-6-to-omega-3 fatty acid ratio in the American diet shifted from roughly 4:1 historically to approximately 20:1 or higher in the modern diet.

The NIH researchers who produced this analysis had no funding or other relationships with the food industry.

Stephen Guyenet and Susan Carlson documented the biological consequences in Advances in Nutrition in 2015: linoleic acid concentration in American adipose tissue increased from approximately 9% of fatty acid composition in the 1960s to approximately 21 to 22% by 2008. The dietary shift is being incorporated into the human body fat at a measurable scale across the population. Americans today have more than twice the concentration of linoleic acid in their body fat than they did in the 1960s.

Why this matters: Linoleic acid is a polyunsaturated fat with multiple double bonds in its carbon chain. These bonds are reactive and susceptible to oxidation. When incorporated into cell membranes and stored in adipose tissue, linoleic acid and its metabolites are exposed to reactive oxygen species that can initiate oxidative cascades. One metabolite of linoleic acid oxidation, 4-hydroxynonenal (4-HNE), is a documented reactive aldehyde that forms protein adducts, damages DNA, and has been found at elevated levels in tissue from patients with neurodegenerative diseases. The full health implications of a fourfold increase in dietary linoleic acid and a threefold increase in tissue accumulation over one century are an active area of research and not yet fully characterized.

(Evidence level: 5 for the documented dietary shift. NIH-funded quantitative analysis using USDA data. Level 5 for the adipose tissue accumulation. directly measured biological change in stored human tissue samples. Level 3 for the health implications of the accumulated linoleic acid, mechanistically plausible, full human evidence ongoing.)

Procter and Gamble, Crisco, and the Organization That Recommended Vegetable Oils

Procter and Gamble introduced Crisco in 1911. Crisco was a partially hydrogenated cottonseed oil, the first commercially successful vegetable shortening sold to American households. P&G developed the product because it had more cottonseed oil than it could sell for industrial lubricant and soap manufacturing. A food application would open a new market.

P&G needed Americans to stop using lard, butter, and tallow. These were the traditional cooking fats that American households had used throughout their history. Marketing Crisco as cleaner, more modern, and eventually as healthier than animal fats required institutional endorsement that advertising alone could not provide.

In 1948, P&G donated $1.74 million to the American Heart Association, transferring proceeds from its radio program sponsorship of "Truth or Consequences." At that time, the AHA was a small professional organization of cardiologists without national reach. The P&G donation transformed it into a national public health institution. The AHA's dietary recommendations in the years following the donation consistently favored polyunsaturated vegetable oils over saturated animal fats, the recommendation that aligned directly with P&G's commercial interest in expanding the market for Crisco and related products.

The AHA's Heart-Check food certification program, established decades later, places an AHA heart symbol on products the organization endorses. Companies pay certification fees to use the mark. Vegetable oil products carry this certification. The AHA does not disclose the founding P&G financial relationship in its current dietary guidance documents or in Heart-Check certification materials.

(Evidence level: 4. The P&G donation is documented in AHA organizational history and contemporaneous accounts. The alignment of AHA recommendations with the promotion of vegetable oil is documented in the historical record of those recommendations. The full financial relationship between the AHA and the food industry in subsequent decades is documented in part through public disclosures, but not completely.)

The Trans Fat Chapter: When Heart-Healthy Became a Banned Substance

Crisco and similar partially hydrogenated vegetable oils produce trans fatty acids as a byproduct of the hydrogenation process. Trans fats give partially hydrogenated vegetable shortening its solid, shelf-stable texture at room temperature. For decades following P&G's founding donation, the AHA endorsed vegetable shortening and margarine made from partially hydrogenated oils as heart-healthy alternatives to saturated animal fats.

Walter Willett at Harvard School of Public Health published influential cohort data in the 1990s from the Nurses' Health Study documenting that trans fat intake was associated with substantially increased cardiovascular disease risk in women. The evidence accumulated across multiple research groups through the 1990s and 2000s.

In 2015, the FDA issued its final determination that partially hydrogenated oils were no longer Generally Recognized as Safe. The ruling took effect in 2018, effectively banning partially hydrogenated oils from the US food supply.

The food product category that the AHA endorsed as heart-healthy for five decades, partially hydrogenated vegetable shortening, was banned by the federal regulator because it killed people.

The AHA now recommends non-hydrogenated versions of the same vegetable oil category. The financial relationships between the AHA and the food industry that produces these oils are not disclosed in the AHA's current dietary guidance. The institutional confidence with which the AHA recommends vegetable oils today is the same institutional confidence with which it recommended vegetable shortening for fifty years before that recommendation was banned.

(Evidence level: 5 for the FDA trans fat GRAS revocation, federal regulatory action with documented effective date. Level 4 for trans fat cardiovascular harm. Multiple large cohort studies, including the Nurses' Health Study, show consistent direction across independent research groups.)

What Seed Oils Do at Cooking Temperatures

Polyunsaturated fats are chemically less stable at heat than saturated or monounsaturated fats because their multiple double bonds are reactive. When heated, these bonds oxidize, producing degradation compounds including aldehydes and cyclic compounds.

Franca De Alzaa, Charles Guillaume, and Lisete Ravetti published a study in Acta Scientific Nutritional Health in 2018 that tested commercial oils at typical home-cooking temperatures. Sunflower oil, soybean oil, and other high-linoleic seed oils produced dramatically higher levels of aldehydes, including 4-HNE and acrolein, than olive oil, butter, or coconut oil at the same temperatures. The difference was not marginal. Seed oils produced substantially more toxic degradation compounds at frying temperatures than traditional whole food fats.

4-HNE is a reactive aldehyde with documented capacity to form protein adducts and damage DNA. Acrolein is classified by the EPA as a probable human carcinogen at high exposure levels.

The smoke point metric, commonly used in cooking publications to rank which oils are safe for high-heat use, does not accurately predict aldehyde production. Extra virgin olive oil, which has a relatively low smoke point according to marketing characterizations, produced fewer toxic degradation compounds than seed oils with higher smoke points in the De Alzaa study. This is because the smoke point measures the temperature at which visible smoke appears, not the temperature at which oxidation and the formation of toxic compounds begin. Monounsaturated olive oil is chemically more stable at heat than polyunsaturated seed oils, regardless of what the smoke point comparison suggests.

(Evidence level: 3 for the cooking oxidation evidence, controlled laboratory study, direction consistent with established fatty acid chemistry. Level 2 for specific human disease implications of dietary aldehyde exposure at typical cooking intake levels, mechanism plausible, definitive human dietary studies not completed.)

The Controlled Trial Data

The two largest controlled trials supporting the recommendation to replace saturated fat with vegetable oil were conducted during the same era when the AHA was developing its dietary recommendations. Both trials used seed oils as the intervention. Both were buried, not fully published by the original investigators. Both were recovered by Christopher Ramsden at the NIH National Institute on Aging and published in the BMJ in 2013 and 2016.

The Minnesota Coronary Experiment randomized over 9,000 institutionalized participants to replace saturated fat with corn oil. Cholesterol dropped in the intervention group. Cardiovascular mortality rose compared to controls. The full data was not published by the original investigators and was found in the garage of a deceased investigator's son.

The Sydney Diet Heart Study randomized men recovering from heart attacks to replace saturated fat with safflower oil. Cholesterol dropped in the intervention group. Cardiovascular and all-cause mortality rose compared to controls. The full data were not published by the original investigators.

Ramsden's recovery of both trials was conducted without funding from the food industry. Both findings appeared in the BMJ. Both are indexed on PubMed. The AHA's 2017 Presidential Advisory recommending replacement of saturated fat with polyunsaturated vegetable oils cited supporting trials and omitted both recovered datasets. The omission was not acknowledged in the document.

The 2017 AHA advisory was co-authored by Frank Sacks, Alice Lichtenstein, and other researchers with disclosed relationships to food companies. Disclosure was made in accordance with the journal's requirements. The presence of the disclosures does not change what the advisory cited and what it did not.

(Evidence level: 4 for the controlled trial data, large RCTs with direct outcome measurement, recovered from archives. The limitation is selective non-publication, which Ramsden's work directly addresses. The direction of both findings is consistent with the linoleic acid and cooking oxidation evidence above.)

Follow the Funding

Procter and Gamble made Crisco. P&G donated $1.74 million to the AHA in 1948. The AHA recommended replacing saturated fat with vegetable oils. P&G sold more Crisco and vegetable oil products. The soybean, corn, canola, and cottonseed agricultural industries benefited from the dietary shift their extracted oils required. The American Soybean Association has funded research supporting soybean oil consumption. The AHA's Heart-Check program generates certification fees from food companies whose products carry the endorsement, including vegetable oil products.

The controlled trials showing vegetable oil replacement increased cardiovascular mortality were not published by the researchers who ran them. The NIH researcher who recovered both trials had no food industry funding. The AHA's 2017 advisory, which omitted both datasets, was authored by researchers with disclosed relationships to the food industry.

The pattern in this article is the same as that documented in article #7 on the Harvard fat-blame research, article #3 on the AHA's sodium recommendations, and article #201 on pharmaceutical research funding. Financial interests shape which research gets published, which gets omitted, and which institutions issue the guidance that reaches physicians and consumers.

What Is Proven, Plausible, and Unknown

Proven (Level 4-5 evidence): Seed oils are manufactured through hexane solvent extraction and high-heat deodorization (Level 5. Documented food manufacturing process). Dietary linoleic acid intake increased from approximately 2% to 8% of calories between 1900 and 2000 (Level 5. NIH-funded quantitative analysis of USDA data, Hibbeln and Ramsden 2011). Human adipose tissue linoleic acid concentration increased approximately threefold between the 1960s and 2008 (Level 5: directly measured biological samples; Guyenet and Carlson 2015). The AHA was established with a $1.74 million donation from Procter and Gamble in 1948 (Level 4. AHA organizational history). The AHA endorsed partially hydrogenated vegetable oils for 5 decades; the FDA banned them in 2018 for cardiovascular harm (Level 5: FDA regulatory action). The Minnesota and Sydney controlled trials, conducted by NIH researchers, found that replacing saturated fat with seed oils increased cardiovascular mortality (Level 4. Large RCTs, BMJ 2013 and 2016). Seed oils produce higher levels of toxic aldehydes at cooking temperatures than olive oil or butter (Level 3: Laboratory measurements; De Alzaa et al., 2018).

Plausible: mechanism documented, full human evidence ongoing (Level 2-3): The fourfold increase in dietary linoleic acid and the threefold increase in tissue linoleic acid concentration are contributing to chronic inflammatory and metabolic disease at the population level through documented oxidative mechanisms (Level 3. Mechanistically consistent, population-level causal attribution ongoing). Cooking seed oils at typical home temperatures produces aldehyde compounds at levels that may contribute to disease outcomes via dietary absorption (Level 2: Chemistry established; human dietary dose-response not characterized).

Unknown (Level 1-2): The precise magnitude of the public health impact attributable specifically to the dietary linoleic acid shift versus other dietary changes occurring simultaneously (refined carbohydrate increase, sugar increase, whole food displacement). The dose-response relationship for 4-HNE exposure through cooking oils at typical household use levels.

The Risk/Reward Verdict

ATH Verdict: Safer Alternative Exists

The whole-food fat alternatives (butter, ghee, and tallow from quality animal sources, cold-pressed olive oil, coconut oil, and avocado oil) have both a historical dietary track record and a stronger independent evidence base. The AHA recommendation of seed oils rests on a founding financial relationship with the company that made Crisco, a selective citation record in its 2017 advisory that omitted the two largest controlled trials of its core recommendation, and a fifty-year endorsement history that included the vegetable oil category the FDA subsequently banned. The cost of switching from seed oils to whole food fats is a one-time change to what is in your kitchen. The downside of making that switch is effectively zero.

What To Do Today

Remove the seed oils from your kitchen. This means soybean oil, corn oil, canola oil, cottonseed oil, sunflower oil, safflower oil, and any product labeled "vegetable oil" (almost always soybean oil). These are the industrially extracted oils; the evidence does not support this.

Replace them with whole food cooking fats. Butter or ghee from grass-fed animals for most cooking: stable at heat, flavorful, and consistent with the human dietary history that predates the chronic disease epidemic. Coconut oil for higher-heat applications: highly saturated, chemically stable, widely used in traditional tropical cultures without the cardiovascular outcomes the AHA associates with saturated fat. Avocado oil or extra virgin olive oil for low-heat cooking, dressings, and finishing: monounsaturated, documented in the PREDIMED trial to reduce cardiovascular events compared to a low-fat diet.

Check processed food labels. Seed oils are in almost every packaged food in the American grocery store. The ingredient list will show soybean oil, corn oil, canola oil, sunflower oil, or the generic "vegetable oil." If those appear in the ingredients, the product contains industrially extracted linoleic acid. The GRAS loophole article (#2) covers why these ingredients reach the food supply without independent pre-market safety review.

For cooking at higher temperatures, butter, ghee, coconut oil, and tallow are the options with the most stable chemical profiles at heat. The smoke-point marketing of avocado oil is legitimate for certain applications, but the primary criterion for choosing a cooking fat is chemical stability at high heat, not smoke point.

Look for verified whole food cooking fats from grass-fed and pasture-raised sources in the ATH Food and Pantry collection. Every cooking fat product in the ATH marketplace discloses its production method and does not include hexane-extracted seed oils.

Go Verify

Read the Hibbeln and Ramsden 2011 paper in the American Journal of Clinical Nutrition. Search "Blasbalg Hibbeln Ramsden changes omega-3 omega-6 United States 2011." It is NIH-funded research using USDA food availability data. Look at Figure 1 showing the linoleic acid intake trend across the 20th century. This is the dietary change that the AHA's recommendation produced at the population level.
Read the AHA's 2017 Presidential Advisory on dietary fats. Search "Sacks Lichtenstein AHA dietary fats cardiovascular disease 2017." Read the disclosure section listing the authors' financial relationships with food companies. Then check whether the advisory cites the Minnesota Coronary Experiment (Ramsden 2016) or the Sydney Diet Heart Study (Ramsden 2013). It does not.
Look at the ingredient list of every oil in your kitchen. Then check the ingredient list of every packaged food in your pantry. Track what percentage contains hexane-extracted seed oils.
Read the FDA's 2015 final determination on partially hydrogenated oils. Search "FDA partially hydrogenated oils final determination 2015." Read the agency's summary of the evidence that led it to remove GRAS status. Note that this is the same oil category the AHA endorsed as heart-healthy for the preceding five decades.
Ask the next physician who recommends vegetable oils over saturated fat: Have you read the recovered data from the Minnesota Coronary Experiment published in the BMJ in 2016 by Christopher Ramsden? If they have not, bring the citation: Ramsden CE et al. BMJ 2016;353:i1246.

Sources and Citations

Blasbalg TL, Hibbeln JR, Ramsden CE, Majchrzak SF, Rawlings RR. "Changes in consumption of omega-3 and omega-6 fatty acids in the United States during the 20th century." American Journal of Clinical Nutrition. 2011;93(5):950-962.
Guyenet SJ, Carlson SE. "Increase in Adipose Tissue Linoleic Acid of US Adults in the Last Half Century." Advances in Nutrition. 2015;6(6):660-664.
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.
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.
De Alzaa F, Guillaume C, Ravetti L. "Evaluation of Chemical and Physical Changes in Different Commercial Oils during Heating." Acta Scientific Nutritional Health. 2018;2(6):2-11.
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.
US Food and Drug Administration. "Final Determination Regarding Partially Hydrogenated Oils (Removing Trans Fat)." Federal Register. 80 FR 34650. Effective June 18, 2018.
Willett WC, Stampfer MJ, Manson JE, et al. "Intake of trans fatty acids and risk of coronary heart disease among women." Lancet. 1993;341(8845):581-585.