The 100-Year Experiment Nobody Agreed To Run
For the vast majority of human existence, humans cooked with animal fats. Tallow. Lard. Duck fat. Butter. Ghee. Bone marrow. The specific fat varied by culture and geography, but the common thread was consistent: the fats humans used came from animals, were minimally processed, and had been part of the human diet for as long as humans and their hominid ancestors had been eating animals, which is at least two million years.
Seed oils are approximately 100 years old. Crisco, the first commercially hydrogenated vegetable shortening, was introduced by Procter and Gamble in 1911. Canola oil (a product of selective breeding from rapeseed, engineered to remove the toxic erucic acid) was developed in the 1970s. Soybean oil at industrial scale became available only after World War II, when the US government subsidized soy production for wartime protein needs and the excess fat was redirected into the food supply. These are not ancient foods. They are industrial products invented within the last century, produced by applying high heat, chemical solvents, and deodorization processes to seeds that humans rarely consumed as fat sources.
How Seed Oils Are Actually Made
Most people have no idea what goes into producing a bottle of canola oil. The process begins with seeds that are cleaned, heated, and mechanically pressed to extract crude oil. The crude oil is then solvent-extracted using hexane (a petroleum-derived chemical) to recover remaining fat. The hexane-oil mixture is then heated to evaporate the solvent. What remains is then refined, bleached, and deodorized (a process called RBD) to remove the natural colours, flavours, and odours that would otherwise make the oil unpalatable.
The deodorization step requires temperatures between 230 and 270 degrees Celsius. At these temperatures, polyunsaturated fatty acids, which constitute 50 to 70 percent of most seed oils, partially oxidize and isomerize. Industrial trans fats are formed. Glycidyl esters and 3-MCPD, compounds classified as probable human carcinogens, are generated. The finished product is a colourless, odourless, chemically altered oil that bears little resemblance to the seed it came from. This is the oil that replaced tallow and lard in restaurant fryers, processed foods, and home kitchens across North America beginning in the mid-20th century.
The Problem With Polyunsaturated Fats at Scale
Oxidative Instability and Aldehydes
Polyunsaturated fatty acids contain multiple carbon-carbon double bonds. Each double bond is a point of chemical vulnerability, a site where oxygen, heat, light, and metal ions can attack the molecule and initiate a chain reaction of oxidation. This process produces lipid peroxidation products, including malondialdehyde and 4-hydroxynonenal (4-HNE).
4-HNE is a highly reactive aldehyde that forms covalent bonds with DNA, proteins, and phospholipids. It is cytotoxic at low concentrations, genotoxic, and directly implicated in the progression of atherosclerosis, Alzheimer's disease, and cancer. Research by Professor Martin Grootveld at De Montfort University demonstrated that a single portion of food fried in sunflower oil contains up to 100 times the safe daily limit of aldehydes set by the World Health Organization. Animal fats, which are predominantly saturated and monounsaturated, do not produce meaningful quantities of aldehydes at normal cooking temperatures.
Linoleic Acid Accumulation in Tissues
Linoleic acid is the dominant omega-6 PUFA in most seed oils. Unlike saturated fats, which the body burns readily for energy, linoleic acid is preferentially incorporated into cell membranes and adipose tissue, where it can persist for months to years. Body fat linoleic acid content, which averaged approximately 6 percent in North Americans in the 1960s, has risen to approximately 21 to 23 percent today, paralleling the increase in seed oil consumption. This matters because linoleic acid in cell membranes is highly susceptible to peroxidation, and membrane-embedded 4-HNE production is orders of magnitude more damaging than oxidation occurring in the pan.
What the Clinical Evidence Shows
The Minnesota Coronary Experiment
The Minnesota Coronary Experiment (1968 to 1973) is one of the largest and most rigorous dietary randomized controlled trials ever conducted. Nearly 9,500 institutionalized participants were randomly assigned to either a diet with saturated fat replaced by linoleic-acid-rich vegetable oil or a standard diet. The vegetable oil intervention successfully reduced total cholesterol by approximately 14 percent. The intervention group had higher all-cause mortality. For participants over 65, each 30 mg/dL reduction in cholesterol was associated with a 22 percent higher risk of death. The data sat unpublished for decades, finally appearing in full in The BMJ in 2016.
The Sydney Diet Heart Study
The Sydney Diet Heart Study (1966 to 1973) replaced saturated fat with linoleic acid-rich safflower oil in men who had recently had a myocardial infarction. The intervention group showed successful cholesterol reduction. They also showed a 70 percent higher risk of cardiovascular mortality compared to the control group consuming saturated fat. Re-analysis of the original data, published in BMJ in 2013, confirmed these findings.
What Ancestral Populations Tell Us
The Maasai of Kenya and Tanzania consumed diets of meat, blood, and whole-milk dairy, extraordinarily high in saturated fat. Traditional Maasai warriors were documented by British physicians in the early 20th century as having no clinical evidence of cardiovascular disease and electrocardiograms showing no signs of cardiac pathology. The Inuit of the Arctic consumed diets of almost entirely animal-derived foods (seal, walrus, caribou, whale blubber) with virtually no plant foods and very high saturated fat intake for much of the year. Pre-contact Inuit populations had low rates of cardiovascular disease and metabolic dysfunction by all available historical accounts. These are consistent with a broader pattern: populations that consumed predominantly animal fat in a pre-industrial context, without refined carbohydrates or processed oils, did not develop the cardiovascular disease profile that defines modern Western populations.
The Practical Implication: What to Cook With Instead
The fats that served human health for millennia are still available:
- Beef tallow: For high-heat cooking, frying, and roasting. Stable, flavourful, rich in oleic acid, CLA, and fat-soluble vitamins from grass-fed animals.
- Lard (pork leaf lard): Particularly high in monounsaturated oleic acid at approximately 45 percent, with a clean flavour profile and high smoke point. The traditional fat of European and Latin American cooking for centuries.
- Butter and ghee: Rich in butyrate, fat-soluble vitamins, and CLA. Ghee's clarification removes milk solids and extends heat stability.
- Extra virgin olive oil: For lower-heat applications and finishing. Predominantly oleic acid, with strong oxidative stability relative to seed oils.
The Bottom Line
Seed oils were not introduced because research showed they were healthier than animal fats. They were introduced because industrial agriculture generated a surplus, a plausible hypothesis provided ideological cover, and a population-level dietary shift followed before the evidence was adequate to justify it. The evidence accumulated since (from clinical trials, mechanistic research, and population data) has not vindicated the shift.
Animal fats are not the problem. They are the food we replaced the problem with.
Rise Nutrition's Grass-Fed Beef Tallow and Premium Pure Lard are rendered from Canadian, pasture-raised animals raised without antibiotics or synthetic hormones. No industrial processing. No hydrogenation. No chemical solvents. Just the cooking fats humans used for every meal in every culture for the entirety of recorded history.
Real food. Nothing else.
Ready to switch? See the complete Canadian guide to beef tallow.
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