Lowering Cholesterol Killed: A Study Buried for 40 Years
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What if lowering your cholesterol increased your risk of death? A forgotten trial from the 1970s, a gold standard blinded randomized control trial, tested swapping saturated fat (like in butter and beef) for unsaturated fat to improve heart health and save lives. To the astonishment of researchers, it did the opposite: the cholesterol-lowering diet didn't save lives—it took them. The lower the cholesterol dropped, the more deaths occurred. The study wasn't published; it was hidden on nine-track tapes in a basement, uncovered decades later.
"Dr. Frantz. I've heard the possibility that there might be some very interesting data in your father's basement. And there was a mouldering old cardboard box there that I opened up and I just immediately thought to myself, Eureka. I have found it."
Was it a conspiracy, an inconvenient truth that didn't fit the narrative, or something else?
The Minnesota Coronary Experiment was a randomized control trial conducted between 1968 and 1973, including 9,423 men and women from six mental hospitals and one nursing home. This setup allowed blinding and rigorous control of diets, though ethically questionable today.
Objective per NIH grant proposal: provide evidence on whether incidence of atherosclerosis and its clinical consequences could be reduced by dietary modification—specifically, swapping saturated fat (butter) for unsaturated fat (vegetable oil).
Unique strength: autopsies on participants after death to examine arteries for cardiovascular plaque progression.
Intervention diet: cholesterol-lowering diet replacing butter with margarine rich in polyunsaturated fats, lower in saturated fats, higher in unsaturated fats (especially omega-6 linoleic acid). Compared to baseline hospital diet:
- Linoleic acid intake increased by 288%
- Saturated fat intake decreased by 51%
Using the Keys equation (named after Ancel Keys), expected cholesterol reduction of 18% in intervention group.
Ancel Keys was a lead investigator; known for controversial Seven Countries Study linking saturated fat to cardiovascular disease.
Low-saturated fat vegetable oil group showed 13.8% reduction in cholesterol, but fared worse:
- 22% higher risk of death for each 30 mg/dL reduction in cholesterol.
- Lower cholesterol correlated with more deaths.
Autopsies: vegetable oil low-saturated fat group had twice as many heart attacks confirmed on autopsy (41% vs 22%) and no benefit for coronary atherosclerosis.
Results not rushed to publication; stored on nine-track tapes in a basement for over 40 years, published in BMJ in 2016.
"remembers everyone just being baffled... hoping that with some new statistical techniques... the results would change."
"The data were not rushed to publication were integrated into the medical knowledge base... Instead, they were effectively buried."
Meta-analysis of 5 qualifying RCTs (swapping saturated fat for vegetable oils, excluding those with large omega-3 increases), encompassing 10,088 participants:
- No evidence of benefit for coronary heart disease or all-cause mortality.
- Trends worse for saturated fat reduction/vegetable oil groups.
Conventional medicine has inertia. High-level opinion: rigorous data alone doesn't always shift established thought.
Critique 1: Too much unsaturated fat. Harvard School of Public Health: diet never consumed by Americans; linoleic acid well above AHA recommendations.
Critique 2: Toxic hidden trans fats (18:2 trans isomers) in intervention diet. Counter: speculation; would raise cholesterol (but it dropped as predicted); dose-response relationship existed in control group too.
Critique 3: Massive attrition (9,423 to 2,355 participants). Counter: institutional setting led to discharges; analysis restricted to ≥1 year stay (logical for outcomes); randomization minimizes bias.
Lowering cholesterol with vegetable oil-rich intervention cost lives, despite successfully targeting the marker. Assumption: lowering cholesterol improves heart disease/death outcomes—proven wrong here.
Data buried for decades sharpens the cautionary tale.
Real lesson: humility.
"Given the limitations of current evidence, the best approach might be one of humility, highlighting the limitations of current evidence and setting a high bar for advising intakes beyond what can be provided by natural diets." (2016 BMJ authors)
Resist turning limited evidence into sweeping prescriptions. Pause before blunt recommendations (e.g., saturated fat bad, cut red meat/butter).
What if lowering cholesterol increases death risk? It might or might not—depends on how. Wisest stance: humility until we know more.
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