The debate over seed oils has ignited into a full-blown cultural war. When HHS Secretary Robert F. Kennedy Jr. declared it was time to "make frying oil tallow again," he threw gasoline on an already blazing nutritional controversy.
As a psychiatrist who has long studied the connection between nutrition and mental health, I find this debate fascinating. The oils we consume may impact our cardiovascular system, brain chemistry, and emotional regulation.
Kennedy's concerns about seed oils—ubiquitous ingredients lurking in everything from your morning coffee creamer to fast food—stand in stark opposition to decades of mainstream nutritional advice. The American Heart Association has long recommended these oils for their supposed cardiovascular benefits.
So what's the truth? Let's examine the evidence without the political noise.
The Two-Pronged Problem
The controversy centers around linoleic acid, an omega-6 fatty acid abundant in seed oils.
"The human body only requires about 1-2% of daily calories from linoleic acid to prevent deficiencies," explains Dr. Kathryn Munoz, a nutritional biochemist and CEO of 4VitaHealth, who has extensive knowledge of fatty acid metabolism. "Yet the average American consumes far more through processed foods and cooking oils. This creates two distinct problems."
The first issue involves biological competition. Omega-6 and omega-3 fatty acids compete for the same metabolic enzymes in your body. When omega-6 levels skyrocket, as in the Western diet, they essentially crowd out essential omega-3s.
"We're seeing omega-6 to omega-3 ratios of 15-17:1 in many Americans," says Dr. Munoz. "From an evolutionary perspective, humans evolved with ratios closer to 1:1 or 4:1. This imbalance may contribute to chronic inflammation and metabolic disorders."
The second concern relates to inflammation. Some—though not all—research suggests that high linoleic acid intake may promote inflammatory processes in the body. When cells metabolize linoleic acid, they produce arachidonic acid, which can be converted into inflammatory compounds.
While some scientists dispute this connection, Dr. Munoz believes context matters: "It's not just about whether omega-6 fats directly cause inflammation. It's about the competition with omega-3s, which we know are anti-inflammatory. By reducing omega-3 availability, high omega-6 consumption could create a perfect storm—increasing inflammatory pathways while simultaneously reducing anti-inflammatory capacity."
The Other Side of the Story
Not everyone in the scientific community agrees that seed oils deserve their villain status. Some research associates higher blood levels of linoleic acid with reduced cardiovascular risk and lower overall mortality.
"People with the highest blood levels of linoleic acid show the lowest risk for death in some observational studies," notes Dr. Munoz. "But we must be careful with these associations. Correlation doesn't prove causation and dietary patterns are notoriously difficult to study in isolation."
The cholesterol-lowering effects of linoleic acid are well-documented. There was a time when doctors specifically recommended vegetable oil by the spoonful for this purpose. However, cholesterol levels are one biomarker among many contributing to heart health.
The Processing Problem
Beyond the nutritional debate lies an industrial reality: most seed oils undergo extensive chemical processing.
Unlike traditional cooking fats like butter or tallow, which are naturally shelf-stable, seed oils contain polyunsaturated fats with multiple double bonds that readily react with oxygen. This makes them prone to rancidity unless heavily processed.
"The manufacturing process for most seed oils is far from natural," explains Dr. Munoz. "These oils are typically extracted using chemical solvents like hexane, then bleached, deodorized, and winterized to remove plant compounds. Antioxidants are added to prevent spontaneous oxidation. This isn't food preparation—it's chemical engineering."
Few studies have examined how this extensive processing affects human health. Preliminary research suggests that processing methods might contribute to some of the health concerns of these oils.
What Should You Cook With?
The stability of cooking oils under heat matters significantly. Oils high in polyunsaturated fats oxidize more readily when heated, potentially creating harmful compounds.
"Olive oil remains the gold standard for health benefits," says Dr. Munoz. "But its lower smoke
point makes it unsuitable for high-heat cooking or deep frying."
Avocado oil offers stability with a favorable fatty acid profile for high-heat cooking. However, most commercial versions undergo significant processing. Among animal fats, grass-fed ghee and tallow provide high smoke points with minimal processing.
Dr. Munoz cautions that genetic factors may influence individual responses to different fats. "People carrying the APOE4 gene variant may need to limit saturated fat intake due to its effects on their cholesterol metabolism."
The Path Forward
With Kennedy and incoming FDA chief Dr. Marty Makary both expressing interest in reviewing the science of seed oils, this nutritional debate may soon receive more rigorous scientific attention.
"We can't wait for randomized controlled trials examining the impact of different cooking oils on health outcomes," says Dr. Munoz. "The question isn't just whether seed oils are harmful, but whether the alternatives are better."
The controversy reminds us that nutrition science continues to evolve, challenging us to question long-held assumptions. In the meantime, moderation, minimal processing, and dietary diversity remain prudent approaches to a healthy diet.
Dr. Keith Ablow is a psychiatrist and author focusing on the connections between nutrition, lifestyle, and mental health.
