Studies

The source records behind the evidence map. Every citation has been verified against a primary source (PubMed / DOI), and each carries a GRADE-lite evidence tier with the reasoning behind it.

Low tierImaging Study
Carbohydrate Restriction-Induced Elevations in LDL-Cholesterol and Atherosclerosis: The KETO Trial
Matthew Budoff et al. - JACC: Advances, 2024
The cross-sectional baseline arm of the Keto-CTA study: in lean, metabolically healthy people whose LDL rose very high on a ketogenic diet, coronary plaque burden was no greater than in matched lower-LDL controls, and LDL-C did not correlate with plaque within either group.
Moderate tierRandomized Controlled Trial
Side Effect Patterns in a Crossover Trial of Statin, Placebo, and No Treatment
James P Howard et al. - Journal of the American College of Cardiology, 2021
Among patients who had stopped statins because of side effects, most statin-attributed symptoms were nocebo. Mean daily symptom intensity did not differ significantly between statin (16.3) and placebo (15.4) months (P=0.39), but both were markedly higher than no-tablet months (8.0, P<0.001), indicating symptoms were driven by the act of taking a tablet rather than the statin itself. The nocebo ratio was 0.90, meaning about 90% of the symptom burden on a statin was also experienced on placebo. This record is the open-access detailed analysis of the SAMSON trial (first reported as a brief letter, Wood et al., NEJM 2020), used here because its figures are publicly verifiable.
High tierRandomized Controlled Trial
Statin treatment and muscle symptoms: series of randomised, placebo controlled n-of-1 trials
Emily Herrett et al. - BMJ, 2021
In a series of n-of-1 RCTs of atorvastatin 20 mg versus placebo among people who had previously reported statin-associated muscle symptoms, there was no overall difference in muscle-symptom scores between statin and placebo periods (mean difference -0.11 on a 0-10 scale, 95% CI -0.36 to 0.14, P=0.40). Withdrawals for intolerable muscle symptoms were similar (9% statin vs 7% placebo), and two thirds of those completing the trial reported restarting statins. The null result indicates that muscle symptoms many patients attribute to statins are largely not caused by the statin itself.
High tierMeta Analysis Of Rcts
Reduction in saturated fat intake for cardiovascular disease
Lee Hooper et al. - Cochrane Database of Systematic Reviews, 2020
This Cochrane meta-analysis of long-term randomised trials found that reducing saturated fat intake for at least two years cut combined cardiovascular events by about 17% (RR 0.83). Critically, it had little or no effect on all-cause mortality (RR 0.96) or cardiovascular mortality (RR 0.95). Benefit was greatest when saturated fat was replaced with polyunsaturated fat or carbohydrate, and was accompanied by only small reductions in cholesterol, weight, and BMI.
Moderate tierProspective Cohort
Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality
Zhong VW et al. - JAMA, 2019
In this pooled analysis of six US cohorts, higher dietary cholesterol intake and higher egg consumption were each associated with higher risk of incident cardiovascular disease and all-cause mortality in a dose-response manner. Crucially, the egg associations became null after adjusting for total dietary cholesterol, suggesting that cholesterol content, not eggs per se, drives the signal. This is observational data and cannot establish causation.
High tierRandomized Controlled Trial
Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial
Christopher D. Gardner et al. - JAMA, 2018
In this 12-month randomized trial, there was no significant difference in weight loss between a healthy low-fat and a healthy low-carbohydrate diet (HLF -5.3 kg vs HLC -6.0 kg; between-group difference 0.7 kg, CI crossing zero). Neither a predefined genotype pattern nor baseline insulin secretion predicted which diet worked better. An inconvenient result for low-carb advocates is that LDL cholesterol rose in the low-carbohydrate group, with 12-month LDL changes significantly favouring the low-fat diet.
Low tierProspective Cohort
Effectiveness and Safety of a Novel Care Model for the Management of Type 2 Diabetes at 1 Year: An Open-Label, Non-Randomized, Controlled Study
Sarah J Hallberg et al. - Diabetes Therapy, 2018
In adults with type 2 diabetes, a continuous remote-care model based on nutritional ketosis markedly improved glycemic control and most cardiovascular risk markers at one year: HbA1c fell from 7.6% to 6.3%, weight dropped 13.8 kg, insulin was reduced or eliminated in 94% of users, triglycerides fell 24%, and HDL rose 18%. The inconvenient, skeptic-relevant signal is that LDL cholesterol rose about 10%. The study is open-label, non-randomized, and funded by Virta Health, the company selling the intervention.
High tierRandomized Controlled Trial
Alirocumab and Cardiovascular Outcomes after Acute Coronary Syndrome
Gregory G Schwartz et al. - New England Journal of Medicine, 2018
The second large PCSK9-inhibitor outcomes trial. Alirocumab on top of intensive statins reduced recurrent major ischemic events (HR 0.85). Unlike FOURIER, it showed a possible all-cause mortality signal (HR 0.85), though this was not formally significant under the trial's prespecified hierarchical testing - so it is a hypothesis, not a proven mortality benefit.
Moderate tierRandomized Controlled Trial
Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts
Ramon Estruch et al. - New England Journal of Medicine, 2018
In high-risk Spanish adults without cardiovascular disease, a Mediterranean diet supplemented with extra-virgin olive oil or mixed nuts reduced major cardiovascular events versus a reduced-fat control diet (hazard ratios 0.69 and 0.72). Absolute event rates were low, so the absolute reduction was modest, and the composite benefit was driven largely by stroke. This is the 2018 corrected-and-republished version: the original 2013 report was withdrawn after randomization protocol deviations were identified, though the revised hazard ratios were essentially unchanged.
High tierRandomized Controlled Trial
Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease
Paul M Ridker et al. - New England Journal of Medicine, 2017
A randomized, double-blind trial of canakinumab (an anti-interleukin-1-beta antibody) in patients with prior MI and elevated hs-CRP. The 150 mg dose significantly reduced recurrent cardiovascular events compared with placebo - without lowering LDL - providing direct evidence that inflammation is an independent, modifiable contributor to cardiovascular risk.
High tierGuideline Or Consensus
Low-density lipoproteins cause atherosclerotic cardiovascular disease. 1. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel
Brian A Ference et al. - European Heart Journal, 2017
The European Atherosclerosis Society consensus panel appraised genetic, epidemiologic, and clinical evidence against formal criteria for causality and concluded that LDL causes ASCVD, citing a consistent dose-dependent, log-linear relationship between cumulative LDL exposure and risk.
High tierRandomized Controlled Trial
Evolocumab and Clinical Outcomes in Patients with Cardiovascular Disease
Marc S Sabatine et al. - New England Journal of Medicine, 2017
Evolocumab, a PCSK9 inhibitor, lowered LDL by 59% (to a median of 30 mg/dL) on top of statins and reduced the primary cardiovascular composite (HR 0.85). It is strong evidence that even very low LDL is safe and beneficial - but it is also a key skeptic exhibit: the absolute benefit was modest, and the short median follow-up (2.2 years) was too brief to test whether halving LDL extends life.
Moderate tierProspective Cohort
Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study
Mahshid Dehghan et al. - Lancet, 2017
In this large international prospective cohort, higher carbohydrate intake was associated with higher total mortality, while higher total fat and each type of fat (including saturated fat) were associated with lower total mortality. Total fat, saturated fat, and unsaturated fats showed no significant association with myocardial infarction or cardiovascular mortality, and saturated fat was inversely associated with stroke. The authors concluded that global dietary guidelines should be reconsidered.
Moderate tierGuideline Or Consensus
Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association
Frank M Sacks et al. - Circulation, 2017
This American Heart Association consensus advisory concludes that replacing saturated fat with polyunsaturated vegetable oil lowers cardiovascular disease risk by roughly 30%, comparable to statin therapy, and recommends reducing saturated fat. The skeptic-relevant caveat is in the same abstract: replacing saturated fat with mostly refined carbohydrates and sugars is not associated with lower cardiovascular rates, so the benefit depends on what replaces the saturated fat.
High tierProspective Cohort
Role of Coronary Artery Calcium Score of Zero and Other Negative Risk Markers for Cardiovascular Disease: The Multi-Ethnic Study of Atherosclerosis (MESA)
Michael J Blaha et al. - Circulation, 2016
Among 13 negative ("downward-shifting") cardiovascular risk markers in a multi-ethnic cohort, a coronary-artery calcium score of zero (CAC=0) was the single strongest, producing the largest downward shift in estimated risk (adjusted mean diagnostic likelihood ratio 0.41 for all coronary heart disease and 0.54 for all cardiovascular disease over 10 years), ahead of carotid intima-media thickness below the 25th percentile. This quantifies the popularized "power of zero": a negative imaging test, especially CAC=0, confers low short-to-intermediate-term risk. Whether to withhold preventive therapy on that basis is a separate question this paper does not settle.
High tierRandomized Controlled Trial
Cholesterol Lowering in Intermediate-Risk Persons without Cardiovascular Disease
Salim Yusuf et al. - New England Journal of Medicine, 2016
The cleanest test of statins in ordinary primary prevention: it enrolled intermediate-risk people without selecting them by cholesterol level. Rosuvastatin lowered LDL by 26.5% and reduced the first coprimary endpoint by 24% (HR 0.76), with an absolute event reduction of roughly 1.1 points over 5.6 years and no excess of diabetes or cancer.
High tierCase Control
Diagnostic Yield and Clinical Utility of Sequencing Familial Hypercholesterolemia Genes in Patients With Severe Hypercholesterolemia
Amit V Khera et al. - Journal of the American College of Cardiology, 2016
Among adults with severe hypercholesterolemia, gene sequencing detected a familial-hypercholesterolemia (FH) mutation in fewer than 2%, yet at the same measured LDL level mutation carriers had far higher coronary-artery-disease risk than non-carriers. Versus a low-LDL no-mutation reference, LDL >=190 mg/dl without a mutation carried a 6-fold higher CAD risk, while LDL >=190 mg/dl with an FH mutation carried a 22-fold higher risk. The mechanism is greater cumulative lifetime LDL exposure in carriers, a natural experiment supporting cumulative LDL burden as causal for CAD.
Moderate tierRandomized Controlled Trial
Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73)
Christopher E Ramsden et al. - BMJ, 2016
Recovered data from the Minnesota Coronary Experiment show that replacing saturated fat with linoleic acid (corn oil) effectively lowered serum cholesterol but did not reduce mortality. Lower serum cholesterol was instead associated with a higher risk of death, and a meta-analysis of five RCTs found no mortality benefit from coronary heart disease or any cause. It is a key skeptic-cited result that lowering cholesterol via linoleic acid did not translate into longer life.
Low tierSystematic Review
Lack of an association or an inverse association between low-density-lipoprotein cholesterol and mortality in the elderly: a systematic review
Uffe Ravnskov et al. - BMJ Open, 2016
This systematic review reports that, in people over 60, higher LDL cholesterol was not associated with higher mortality and was usually inversely associated with all-cause mortality, with no cohort showing the harm predicted by the cholesterol hypothesis. It is, however, a contested, skeptic-authored review: several authors (including Ravnskov, Kendrick, and Malhotra) have written books criticising the cholesterol hypothesis, it was funded by the Western Vascular Institute, and it relied on crude vote-counting with no pooled effect estimate, drawing heavy post-publication criticism (CEBM Oxford, Science Media Centre).
High tierMeta Analysis Of Rcts
Efficacy and safety of LDL-lowering therapy among men and women: meta-analysis of individual data from 174,000 participants in 27 randomised trials
Cholesterol Treatment Trialists' (CTT) Collaboration et al. - The Lancet, 2015
The individual-participant meta-analysis that directly answers "do statins work in women?" Per 1.0 mmol/L of LDL lowering, statins reduced major vascular events to a similar proportional extent in women and men, and reduced all-cause mortality in both sexes - rebutting the recurring claim that the evidence base does not support treating women.
Very low tierNarrative Review
How statistical deception created the appearance that statins are safe and effective in primary and secondary prevention of cardiovascular disease
David M Diamond et al. - Expert Review of Clinical Pharmacology, 2015
A critical commentary arguing that statins lower cholesterol but have not substantially improved cardiovascular outcomes, and that the appearance of benefit was created by reporting relative (rather than absolute) risk reduction while downplaying adverse effects.
High tierRandomized Controlled Trial
Ezetimibe Added to Statin Therapy after Acute Coronary Syndromes
Christopher P Cannon et al. - New England Journal of Medicine, 2015
The first trial to show that adding a NON-statin LDL-lowering drug on top of a statin further reduces events. Ezetimibe (which blocks intestinal cholesterol absorption) lowered LDL from 69.5 to 53.7 mg/dL and modestly but significantly cut the composite endpoint (HR 0.936). Because ezetimibe works nothing like a statin, this is key evidence that LDL lowering itself - not a statin side effect - drives benefit.
Moderate tierRandomized Controlled Trial
Effects of low-carbohydrate and low-fat diets: a randomized trial
Lydia A. Bazzano et al. - Annals of Internal Medicine, 2014
In this 12-month randomized trial, a low-carbohydrate diet (under 40 g/day) produced greater weight loss than a low-fat diet (a 3.5 kg difference) and better cardiovascular risk-factor changes: higher HDL, lower triglycerides, and a lower total/HDL cholesterol ratio. There was no significant difference in LDL cholesterol between the diets, and the trial measured risk factors only, with no clinical cardiovascular endpoints.
Moderate tierProspective Cohort
Discordance of low-density lipoprotein (LDL) cholesterol with alternative LDL-related measures and future coronary events
Samia Mora et al. - Circulation, 2014
In healthy women, LDL-C was sometimes discordant with non-HDL-C, apoB, and LDL particle number. When the alternative measures were higher than LDL-C, coronary risk was higher, and vice versa - so risk can be mis-estimated when LDL-C is used alone.
High tierMeta Analysis Of Rcts
The effects of lowering LDL cholesterol with statin therapy in people at low risk of vascular disease: meta-analysis of individual data from 27 randomised trials
Cholesterol Treatment Trialists' (CTT) Collaborators et al. - The Lancet, 2012
In an individual-participant meta-analysis of 27 statin trials, each 1.0 mmol/L LDL reduction cut major vascular events by about 21%, and the proportional benefit was at least as large in the lowest-risk people. In those with 5-year risk under 10%, that translated to about 11 fewer major vascular events per 1,000 over 5 years.
High tierMendelian Randomization
Effect of long-term exposure to lower low-density lipoprotein cholesterol beginning early in life on the risk of coronary heart disease: a Mendelian randomization analysis
Brian A Ference et al. - Journal of the American College of Cardiology, 2012
Using nine genetic variants as a proxy for lifelong lower LDL, the study found that long-term exposure to lower LDL beginning early in life was associated with roughly a 54.5% lower risk of coronary heart disease per 1 mmol/L - about three times the per-unit benefit seen when statins are started later in life.
High tierMeta Analysis Of Rcts
Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials
Cholesterol Treatment Trialists' (CTT) Collaboration et al. - The Lancet, 2010
A large meta-analysis of 26 statin trials found dose-dependent reductions in cardiovascular events with LDL lowering: each 1.0 mmol/L reduction cut major vascular events by about 22%, with no threshold below which benefit ceased, and a roughly 10% reduction in all-cause mortality per 1.0 mmol/L.
High tierMeta Analysis Of Rcts
Statins and risk of incident diabetes: a collaborative meta-analysis of randomised statin trials
Naveed Sattar et al. - The Lancet, 2010
The defining quantification of the statin-diabetes harm. Pooling 13 statin RCTs, statin therapy was associated with a 9% relative increase in incident diabetes (OR 1.09). In absolute terms the harm is small - about one extra case for every 255 patients treated for four years - which the authors judged low against the cardiovascular benefit.
Low tierSystematic Review
Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease
Patty W Siri-Tarino et al. - The American Journal of Clinical Nutrition, 2010
This pooled analysis of 21 prospective cohort studies found no significant association between dietary saturated fat intake and coronary heart disease, stroke, or total cardiovascular disease when comparing the highest and lowest intake groups. It is one of the most frequently skeptic-cited null results on saturated fat. The result must be read alongside its funding: the paper declared "no conflicts of interest" yet was supported by the National Dairy Council, with one co-author funded by a Unilever fellowship.
High tierMendelian Randomization
Genetic variants associated with Lp(a) lipoprotein level and coronary disease
Robert Clarke et al. - The New England Journal of Medicine, 2009
Two common LPA gene variants were strongly associated with both higher Lp(a) lipoprotein levels and higher coronary-disease risk. Crucially, after adjustment for the measured Lp(a) level the genotype-score association with coronary disease was abolished, which the authors interpret as supporting a causal role for Lp(a). This genotype-based (Mendelian-randomization-style) result favours the causal lipid hypothesis specifically for Lp(a).
High tierMendelian Randomization
Genetically elevated lipoprotein(a) and increased risk of myocardial infarction
Pia R Kamstrup et al. - JAMA, 2009
In Danish general-population cohorts, both observational and genetic analyses linked higher lipoprotein(a) to higher myocardial-infarction risk. Using the LPA KIV-2 size polymorphism as a genetic instrument (Mendelian randomization), genetically elevated Lp(a) was associated with a hazard ratio of 1.22 per doubling, an estimate largely free of confounding and reverse causation. The authors concluded the data are "consistent with a causal association," cautious wording rather than a claim of definitive proof.
High tierProspective Cohort
Coronary calcium as a predictor of coronary events in four racial or ethnic groups
Detrano R et al. - New England Journal of Medicine, 2008
In a multi-ethnic cohort free of baseline cardiovascular disease, coronary- artery calcium (CAC) measured by CT was a strong, independent predictor of incident coronary heart disease across all four racial/ethnic groups. Relative to a CAC score of 0, the adjusted risk of a coronary event was about 7.73-fold higher for scores of 101-300 and 9.67-fold higher for scores above 300. CAC added predictive value beyond standard risk factors; this is a prognostic, risk-marker result rather than a test of any treatment.
High tierRandomized Controlled Trial
Rosuvastatin to prevent vascular events in men and women with elevated C-reactive protein
Paul M Ridker et al. - New England Journal of Medicine, 2008
A primary-prevention trial that selected people by inflammation (high hs-CRP) rather than high LDL. Rosuvastatin nearly halved the primary cardiovascular endpoint (HR 0.56). It is both a pillar of the "treat lower-risk people" case and a favourite skeptic target: it was industry-funded and stopped early, which tends to inflate the apparent effect.
High tierRandomized Controlled Trial
Prevention of coronary and stroke events with atorvastatin in hypertensive patients who have average or lower-than-average cholesterol concentrations, in the Anglo-Scandinavian Cardiac Outcomes Trial - Lipid Lowering Arm (ASCOT-LLA): a multicentre randomised controlled trial
Peter S Sever et al. - The Lancet, 2003
A primary-prevention trial in hypertensive patients with average or below-average cholesterol. Atorvastatin cut the primary endpoint of nonfatal MI plus fatal CHD by 36% (HR 0.64), prompting early termination. Stroke fell too, but all-cause mortality was not significantly reduced - a pattern typical of shorter primary-prevention trials.
High tierRandomized Controlled Trial
Prevention of coronary heart disease with pravastatin in men with hypercholesterolemia
J Shepherd et al. - New England Journal of Medicine, 1995
The first large primary-prevention statin trial. In hypercholesterolaemic men with no prior heart attack, pravastatin lowered LDL by 26% and cut the combined risk of nonfatal MI or coronary death by 31%. All-cause mortality fell 22%, but that result was borderline and not statistically significant (p=0.051).
High tierRandomized Controlled Trial
Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S)
Scandinavian Simvastatin Survival Study Group - The Lancet, 1994
The first statin trial to show that lowering cholesterol reduces total mortality, not just cardiovascular events. In coronary patients, simvastatin cut the relative risk of death by 30% over a median 5.4 years, driven by fewer coronary deaths, with non-cardiovascular deaths essentially unchanged.