Vegetable Oils: The Unknown Story

How Did Vegetable Oils Make Their Way Into the American Diet?

Nina Teicholz

Discover how “heart-healthy” seed oils quietly replaced traditional animal fats in the American kitchen—and why that shift still shapes our health today.

Synopsis

In this talk, investigative science journalist Nina Teicholz traces the surprising industrial origins of modern “vegetable oils,” explaining how seed-derived fats like soybean and corn oil went from lubricating machinery to dominating the American diet. She describes how hydrogenation made unstable seed oils solid enough to replace traditional fats such as butter, lard, tallow, coconut, and palm oil, paving the way for products like Crisco and margarine that were aggressively marketed as clean, modern, and superior to animal fats. Teicholz then shows how public health institutions, especially the American Heart Association, partnered with industry to promote polyunsaturated vegetable oils as heart-healthy despite randomized controlled trials that failed to show cardiovascular or mortality benefits, and in some cases revealed higher rates of cancer and other adverse outcomes. She also highlights concerns about omega‑6–rich seed oils, their inflammatory potential, and the toxic oxidation products formed when these oils are repeatedly heated in restaurant fryers, contrasting them with more stable saturated fats and carefully used olive oil. The video concludes with practical guidance to minimize seed oil exposure by favoring traditional saturated fats for cooking, using olive oil for unheated applications, and avoiding fried foods made with industrial seed oils whenever possible.

Summary

Vegetable oils marketed as “heart healthy” actually originate from industrial seed oils such as cottonseed, soybean, corn, safflower, and others that were first used as lubricants and lamp oils before being repurposed as food.
The development of hydrogenation technology allowed manufacturers to turn rancid, unstable seed oils into solid, shelf-stable fats, leading to iconic products like Crisco and modern margarine that displaced traditional cooking fats like butter, lard, and tallow in the early 20th century.
Aggressive marketing campaigns framed Crisco and margarine as modern, clean, liberating alternatives to the “messy” world of animal fats, and by mid‑century these hardened vegetable oils were deeply embedded in home cooking and processed foods.
As heart disease rose, the American Heart Association and influential researchers such as Ancel Keys promoted the “diet‑heart” hypothesis, encouraging people to replace saturated fats with polyunsaturated vegetable oils—a recommendation that aligned closely with the financial interests of companies like Procter & Gamble.
Large randomized controlled trials that replaced animal fats with high‑PUFA seed oils often showed no reduction in cardiovascular or total mortality, and in several cases found higher rates of cancer, gallstones, strokes, and potential liver issues in the high–vegetable oil groups.
Trans fats, formed by partial hydrogenation of these oils, were eventually banned largely for their effect on LDL cholesterol, but industry responded with newer, more complex technologies (genetically modified oils, interesterified fats, high‑oleic seed oils) rather than returning to traditional saturated fats, in part because dietary guidelines still cap saturated fat intake.
Teicholz emphasizes that seed oils are rich in omega‑6 polyunsaturated fats, which oxidize easily, can generate toxic aldehydes when heated, and may contribute to inflammation and poor omega‑3/omega‑6 balance, especially in diets heavy in processed foods, restaurant fried foods, and nut‑based products.
She recommends using stable saturated fats (such as lard, tallow, suet, coconut, and palm oil) for cooking, reserving olive oil for unheated uses like salads, avoiding restaurant fried foods cooked in seed oils, and questioning longstanding public‑health advice to replace saturated fats with polyunsaturated vegetable oils.

Description

Nina Teicholz is a New York Times bestselling investigative science journalist who has played a pivotal role in challenging the conventional wisdom on dietary fat. Her groundbreaking work, “The Big Fat Surprise,” which The Economist named as the number 1 science book of 2014, has led to a profound rethinking on whether we have been wrong to think that fat, including saturated fat, causes disease. Nina continues to explore the political, institutional, and industry forces that prevent better thinking on issues related to nutrition and science, and she has been published in the New York Times, the New Yorker, the British Medical Journal, Gourmet, the Los Angeles Times, and many other outlets.

Transcript Summary

From “big fat lie” to “big fat surprise”

Teicholz opens by acknowledging the frustration many people feel when they discover that much of what they’ve been told about dietary fat may be misleading or wrong. She explains that she originally wanted to title her book “The Big Fat Lie,” but softened it to “The Big Fat Surprise,” while still emphasizing that we’ve lived for decades in an “alt‑fat world” where official nutrition advice misrepresented the evidence on fat and health.

What “vegetable oils” really are

She then asks what vegetable oils actually are and notes that the term is a marketing invention, since these oils are not made from vegetables like broccoli but from seeds and beans such as soybeans and cottonseed. In technical circles they’re called seed oils, and she contrasts them with the traditional fats humans used for millennia, including tallow, suet, lard, butter, coconut oil, and palm oil, which come from animals or tropical fruits and were the primary cooking fats in different cultures.

Industrial origins of seed oils

Teicholz describes how, before they entered the food supply, oils from whales and later cottonseed were used primarily for industrial purposes as lubricants and in machinery, not as food. Cottonseed oil, a byproduct of the booming cotton industry in the American South, was initially used to replace whale oil and only later slipped into the human food supply as an adulterant in butter.

Chemistry of fats and the rise of hydrogenation

Because seed oils are naturally unstable and prone to rancidity, they were difficult to use as food until chemists developed hydrogenation to make them solid and shelf‑stable. Teicholz reviews basic fat chemistry, explaining that saturated fatty acids with no double bonds are straight, pack tightly, and form solids, whereas polyunsaturated fatty acids with multiple double bonds are “squiggly,” leave space between molecules, and remain liquid. Hydrogenation straightens out these unsaturated fats, and she describes visiting a hydrogenation plant where gray, rancid oil from seeds is processed with metal catalysts, solvents like hexane, deodorization, and winterization to transform it into something palatable.

Crisco, margarine, and the marketing of modernity

Once Procter & Gamble stabilized cottonseed oil around 1910, they first sold it as soap but soon realized it looked like lard and could be marketed as a cooking fat. In 1911 they launched Crisco, introducing hydrogenated seed oils into the human diet on a large scale and promoting them as bright, modern, and hygienic alternatives to animal fats that supposedly came from dark, unsanitary slaughterhouses. Cookbooks and pamphlets replaced butter and lard with Crisco in recipes, and by mid‑century margarine—originally made from lard and coconut oil but later from polyunsaturated seed oils—rose as a cheaper competitor to butter, sparking a long, bitter conflict with the dairy industry over taxes, labeling, and the right to sell yellow‑colored margarine.

World War II, price pressures, and mainstream acceptance

Teicholz explains that economic pressures and World War II accelerated margarine’s acceptance, as vegetable‑oil products were cheaper than butter and eventually considered acceptable even on elegant tables. By the mid‑20th century, Crisco and margarine were firmly entrenched as the main routes by which hydrogenated vegetable oils entered the American food supply, while later innovations allowed liquid seed oils to be bottled and sold directly to consumers once chemists improved their shelf stability.

The diet‑heart hypothesis and institutional alliances

She then moves to the rise of heart disease and the emergence of the diet‑heart hypothesis, focusing on Ancel Keys and the claim that saturated fat and cholesterol cause heart disease. During the panic following President Eisenhower’s 1955 heart attack, the American Heart Association (AHA), which had been relatively small and underfunded, received a huge financial boost from Procter & Gamble through a popular radio contest, suddenly transforming it into a major nonprofit organization. Teicholz recounts how the AHA, heavily supported by vegetable‑oil interests, began promoting polyunsaturated seed oils as a way to prevent heart attacks, even featuring promotional materials linking Crisco to heart health and drawing criticism from scientists who saw this as blatant commercialism.

Trials that challenged the seed‑oil narrative

Teicholz highlights large randomized controlled trials in which traditional animal fats were replaced with corn, soy, safflower, and cottonseed oils, noting that these studies—often cited as gold‑standard evidence—did not show reductions in cardiovascular or total mortality. Instead, some trials, such as the LA Veterans Study, found that participants consuming high‑PUFA diets had significantly higher rates of cancer and other problems like gallstones, strokes, and possible liver damage, even though their cholesterol levels were successfully lowered. She notes that NIH convened high‑level meetings to discuss the troubling findings but ultimately prioritized cholesterol lowering and the fight against heart disease over publicizing potential harms of vegetable oils.

Dramatic rise in vegetable oil consumption

Using historical data, Teicholz explains that vegetable oil intake in the United States rose from near zero to about 7–8 percent of total calories, driven largely by soybean oil. This growth, she argues, is unique among food groups and was powered by the AHA’s support, the U.S. dietary guidelines’ recommendation to replace saturated fat with polyunsaturated oils, and the widespread adoption of hydrogenated soybean oil as the backbone of processed foods, from cookies and crackers to chips and cereals.

Seed oils, omega‑6 fats, and inflammation

She then reframes vegetable oils as major sources of omega‑6 polyunsaturated fats and notes that omega‑6s are known to have pro‑inflammatory properties when consumed in excess. While people often focus on increasing omega‑3 intake to improve their omega‑3/omega‑6 ratio, Teicholz suggests that a more effective strategy is simply to reduce omega‑6 intake by avoiding seed oils and being mindful of high‑PUFA foods such as nuts and nut flours, which can easily drive omega‑6 consumption higher than intended.

Seed oils in restaurants and toxic oxidation products

Teicholz devotes significant attention to what happens when seed oils are repeatedly heated in restaurant fryers, explaining that polyunsaturated fats oxidize readily and produce toxic compounds, including aldehydes, when used for deep frying. She recounts research in which a scientist measured hundreds of oxidation products, including high levels of aldehydes (some of which serve as biomarkers for cancer risk), in fried foods such as chicken nuggets and French fries from fast‑food outlets. She also shares stories from vegetable‑oil scientists about severe cleaning problems in restaurants after trans‑fat bans, such as polymerized oil residues clogging drains, coating walls, and even causing uniforms to spontaneously combust or explode in dryers, hinting at the instability and reactivity of these heated oils.

Trans fats, bans, and their replacements

Teicholz reviews how partially hydrogenated oils, which contain trans fats, were heavily used in restaurants and processed foods until data emerged linking trans fats to increased LDL cholesterol and other adverse health outcomes. Although she questions the narrow focus on LDL and the reliance on epidemiological evidence for the ban, she is not sorry trans fats were removed, given broader evidence of harm. The problem, she argues, is that instead of returning to simple, stable saturated fats, industry shifted to new technologies such as genetically modified soybeans designed to produce more stable fatty acid profiles, increased use of high‑oleic seed oils like sunflower, and the development of interesterified fats—all of which are more complex and expensive and may carry unknown long‑term risks.

Tropical oils and the “tree lard” campaign

She tells the story of how tropical oils like coconut and palm oil were once used as stable, non‑animal fats in food manufacturing but became targets of a coordinated campaign by the American Soybean Association, which saw them as competition. Public‑relations efforts labeled tropical oils as “tree lard” and depicted foreign producers as threatening “wholesome American farmers,” contributing to the removal of tropical fats from many processed foods and replacing them with hydrogenated seed oils. Teicholz notes that recent American Heart Association advisories have again singled out coconut oil for criticism, which she suggests may reflect ongoing financial ties to vegetable‑oil interests and a lingering perception of coconut oil as a competitive threat.

Passionate activists and policy shifts

Teicholz also describes how passionate individuals, such as Phillip Sokolof—a wealthy heart attack survivor convinced that tropical oils were deadly—spent personal fortunes buying newspaper ads and pressuring food companies to remove coconut and palm oils from their products. Combined with advocacy from groups like the Center for Science in the Public Interest, these efforts led major brands to eliminate tropical oils and shift to polyunsaturated, often hydrogenated, seed oils in restaurants and packaged foods.

The continuing dominance of seed oils

By the late 1980s, Teicholz explains, virtually all fats used in restaurants, cafeterias, and processed foods in the U.S. were hydrogenated vegetable oils, a pattern she suggests has parallels in other countries. Even after trans fats were banned, restaurants largely reverted to non‑hydrogenated seed oils like soybean and corn oil, leaving most fried foods today still cooked in unstable, oxidation‑prone oils.

Olive oil, monounsaturated fats, and practical guidance

Teicholz distinguishes olive oil from seed oils by noting that it is rich in monounsaturated fats, which have only one double bond and thus fewer sites for oxidation and aldehyde formation compared with polyunsaturated fats. She cites experiments showing that heating polyunsaturated oils produces the highest levels of toxic oxidation products, monounsaturated oils produce intermediate amounts, and saturated fats produce the least because they have no double bonds. On that basis, she recommends using olive oil primarily for cold applications such as salad dressings, avoiding canola and other polyunsaturated oils for cooking, and relying on saturated fats like lard and tallow for heat-based cooking.

Rethinking saturated fat limits

Teicholz concludes by arguing that we should reconsider the official limits on saturated fat, since those guidelines prevent a straightforward return to traditional, stable fats that do not oxidize easily and have long historical use. She suggests that the current advice to replace saturated fats with polyunsaturated vegetable oils is “hanging by a thread,” propped up by epidemiological studies that conflict with randomized controlled trials showing no mortality benefit and potential harms, and encourages people to question this narrative and focus instead on reducing unstable, omega‑6‑rich seed oils in their diets.