America may be poised for a nutrition policy reset, one that starts to reverse the epidemic of chronic disease afflicting a majority of Americans. With Robert F. Kennedy Jr. tapped to lead the Department of Health and Human Services, the incoming administration has an opportunity to scrutinize a once-rare but now pervasive ingredient in our diet: seed oils.
Over the last 125 years, our consumption of these oils, extracted from soybeans, peanuts, sunflowers, safflower, and other seeds and beans, has multiplied more than any other food source. Between 1909 and 1999, Americans’ intake of soybean oil alone increased more than a thousand-fold. Today, linoleic acid, the main fatty acid in seed oils, is responsible for up to 8-10% of our total caloric intake, up from near zero just over a century ago.
That rise has far-reaching health implications that have often been downplayed or dismissed by some of our nation’s foremost nutrition experts. To turn the page on our chronic disease crisis, the new administration should initiate a thorough, science-based review of seed oils. This effort could include the Food and Drug Administration’s reexamination of its “generally recognized as safe” status, a process that would fall within RFK Jr.’s purview if Senate-confirmed.
Seed oils weren’t originally considered fit for human consumption; they were largely developed as machine lubricants during the Industrial Revolution. It was Procter & Gamble that introduced them into the food supply via its product Crisco in 1911 and aggressively marketed them as a modern-day alternative to lard.
That push got a massive boost in 1961 from the American Heart Association, when it recommended consuming polyunsaturated seed oils over saturated fats such as lard and butter as the key strategy for preventing heart disease. This advice launched a new era for seed oils: Now they could be marketed as “heart-healthy.”
But it’s safe to say that the AHA position may have been shaped by a sizable donation from P&G in 1948, equivalent to $20 million today, that, according to the AHA, was the “bang of big bucks” that “launched” the group. To this day, P&G continues to support AHA activities, and the AHA remains staunchly in favor of seed oils.
Experts who questioned the pro-seed oil narrative faced organized opposition. The first major blow came in the late 1970s as concerns surfaced about trans fats, a byproduct of oils when they are hardened to make products such as Crisco. Scientists who published papers critical of them faced relentless attacks by the Institute for Shortening and Edible Oils, the seed oil trade group.
Mary Enig, an early trans fat researcher, told me several ISEO members visited her after she authored a paper linking trans fats to higher cancer rates. “They said that they’d been keeping a careful watch to prevent articles like mine from coming out in the literature and didn’t know how this horse had gotten out of the barn,” she told me. Other researchers said they endured endless adversarial questions at conferences.
While Enig soldiered on, others were so discouraged they left academia altogether. With forceful headwinds, it took another 40 years for trans fats to be banned.
Still, other findings of seed oil researchers have been equally troubling. Studies show these oils oxidize easily, which fuels inflammation. Omega-6 fatty acids in seed oils displace healthier omega-3s in cell membranes. Large, gold-standard clinical trials found that lowering cholesterol, whether through seed oil consumption or other means, increased cancer mortality rates.
By the 1980s, these findings were worrisome enough that the National Institutes of Health convened four high-level workshops. Rather than issue public warnings on seed oils, however, the NIH decided any concerns shouldn’t “contradict” its primary message about lowering cholesterol. It was a pattern — ignoring evidence of seed oils’ harm in favor of preserving prevailing orthodoxy on dietary fats.
When I broke the seed oil story a decade ago, including introducing the term “seed oils,” the evidence against these oils was deeply concerning.
Seed oil is chemically unstable. Its fatty acids degrade into oxidation products such as free radicals and degraded triglycerides. In one analysis, 130 volatile compounds were isolated from a piece of fried chicken, and these oxidation products can pass through the blood-brain barrier.
The products include toxins such as acrolein, generated by smoking cigarettes, and aldehydes, which cause rapid cell death and interfere with DNA and RNA. Aldehydes have also been implicated in neurodegenerative conditions, including Alzheimer’s disease.
Seed oils degrade and oxidize even at room temperature, but heat accelerates the process, making frying especially hazardous. Sources told me that in U.S. fast-food restaurants, oxidized seed oil coats the walls with a layer so thick that it can’t be removed by sandblasters.
Industry experts are aware of these problems. In 2021, University of Massachusetts at Amherst professor Eric Decker gave a talk to commemorate receiving a prestigious industry award (sponsored by soybean oil producer MilliporeSigma) titled, “Lipid [fat] oxidation — why it continues to be such a challenge.” Decker spoke about how seed oils produce free radicals, “can cause dysfunction of proteins,” are a “negative factor for the microbiome,” and are overall “negative to health.”
Yet, public health institutions remain staunch supporters. Federal dietary guidelines still recommend consuming about 5.5 teaspoons of industrial seed oils daily while limiting saturated fats.
Simply put, we made the wrong choice on good vs. bad fats. Whole, natural animal fats are stable when heated and don’t produce the same harmful byproducts as seed oils. While seed oil must be refined, bleached, deodorized, “winterized,” and stabilized in factory settings, butter requires nothing more than shaking milk in a container.
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Furthermore, systematic reviews and meta-analyses on randomized, controlled clinical trials routinely find that saturated fats have no effect on cardiovascular or total mortality and little to no effect on cardiovascular events such as heart attacks.
For the health and safety of all Americans, it’s time to correct course. Our top nutrition policy, the Dietary Guidelines for Americans, should eliminate outdated caps on saturated fats. The new administration should prioritize a comprehensive review of the seed oils that have largely replaced them. Our policies and diets should align with the science of seed oils and healthy fats.
Nina Teicholz is a science journalist and author with a Ph.D. in nutrition.
How seed oils took over our diet and what it means for our health
