Seed oils — canola, soybean, corn, sunflower — supply far more of the American diet than a century ago; US soybean-oil intake rose more than a thousandfold between 1909 and 1999. The fight over whether that's harmful has reached Washington: HHS Secretary Robert F. Kennedy Jr. champions "Make Frying Oil Tallow Again," Steak 'n Shake switched all 436 US locations to beef tallow in early 2025, and the May 2025 MAHA report flagged seed oils — while nutrition scientists push back hard.

1. Seed Oils Are Fine — Even Good for You (American Heart Association, Christopher Gardner)

Swapping butter and tallow for seed oils is one of the most evidence-backed moves in all of nutrition.

The strongest evidence in nutrition says replacing saturated fat with seed oils protects your heart. The American Heart Association's review of randomized trials found that cutting saturated fat and replacing it with polyunsaturated vegetable oil reduced cardiovascular disease by about 30% — a benefit it likened to statins. A 2020 Cochrane review of 13 randomized trials reached a similar conclusion: less saturated fat, swapped for polyunsaturated fat, means fewer cardiac events.

The "omega-6 is inflammatory" claim doesn't hold up in people. Christopher Gardner, a Stanford nutrition scientist and former chair of the AHA's nutrition committee, says the popular logic — omega-3s are anti-inflammatory, so omega-6s must be the opposite — is simply wrong. Trials that raise dietary linoleic acid don't raise inflammatory markers, and people with the highest linoleic-acid blood levels have lower rates of heart disease and diabetes, not higher. Johns Hopkins' 2025 review called the case against seed oils weak.

2. Bring Back Butter and Tallow (RFK Jr., Cate Shanahan)

Industrial seed oils are a 20th-century experiment run on the human body — and the chronic-disease era is the result.

The rise of seed oils shadows the rise of obesity, and the movement isn't willing to call that a coincidence. Kennedy calls seed oils one of the "driving causes" of the obesity epidemic, sells "Make Frying Oil Tallow Again" merchandise, and praised Steak 'n Shake for frying in 100% beef tallow. The May 2025 MAHA Commission report formally flagged seed oils' "potential role in inflammation."

The case is that processing, oxidation, and an omega-6 surplus harm the body in ways an LDL reading misses. Cate Shanahan, whose book "Dark Calories" dubs canola, corn, soy and five others the "hateful eight," argues the oils are oxidative, damage cell membranes, and drive inflammation and metabolic disease. Casey Means, the MAHA figure and "Good Energy" co-author, folds seed oils into her broader case against ultra-processed food. The remedy, they say, is the fats humans cooked with for millennia: butter, tallow, olive and coconut oil.

3. You're Both Blaming the Wrong Thing (Cleveland Clinic, Memorial Sloan Kettering)

The cooking oil is a distraction. The problem is the ultra-processed food it usually arrives in.

Seed oils are mostly a marker of junk food, not the reason it's junk. Registered dietitians at Cleveland Clinic, Memorial Sloan Kettering and Mayo Clinic argue the foods highest in seed oils — chips, fast food, packaged snacks — are calorie-dense, low in fiber and high in sugar and salt, and that is what makes them unhealthy, not the oil itself. Frying a home-cooked vegetable in canola is not the same as eating a bag of chips.

The headline science gets read for far more than it shows. A 2025 study found colon tumors carried more omega-6-derived inflammatory compounds than healthy tissue, and it ricocheted around social media as proof seed oils cause cancer — but the study's own corresponding author said they never measured seed oils or cooking in patients, and fact-checkers said it shows no such thing. The case for tallow is thin too: direct studies on it are scarce, and a controlled-diet comparison found butter and tallow raised LDL more than olive oil did.

Where This Lands

The mainstream science is genuinely strong on one narrow point: swap saturated fat for seed oil and your LDL and heart-disease risk go down. The MAHA case is strongest as suspicion — the thousandfold rise in seed-oil intake really does shadow the chronic-disease era, even if cause hasn't been pinned down — and weakest on its affirmative claim that tallow is healthier, which has little direct evidence behind it. The dietitians may hold the most defensible ground: that the cooking oil is a sideshow next to how processed the food around it is. Whether you pour out the canola depends on whether you trust the trials, the ancestral logic, or the reminder that a fry is a fry no matter what's in the pan.

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