Study analysis · Frontiers in Nutrition · 2021
Butter and red meat could be shortening your life — but olive oil and nuts might help you live longer, according to a 17-year study of over 100,000 people.
Eating more good fats like those in fish, nuts, and plants can help you live longer, while too much saturated fat from meat and butter may increase your risk of early death.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study watched a big group of people for many years to see how their diet relates to their chances of dying. It found links between certain fats and death risk, but it can't prove that the fats caused the changes — other lifestyle factors might be involved.
What’s the bottom line?
This study looked at what kinds of fat people eat and how long they live. It found that some fats are better than others.
How strong is this study?
The study is well-done because it followed lots of people for a long time and asked detailed questions about their health and diet. However, since it didn’t randomly assign diets, we can’t say for sure that the fats themselves caused the differences in health.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
38 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=101832)+20/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 552 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
This design cannot establish causation — the findings describe an association, not a cause. This is an observational cohort study; it cannot establish causation due to potential residual confounding, lack of randomization, and inability to control all variables. The study design only allows for identification of associations.
Key takeaways
- 01
Eating more saturated fat was linked to 13% higher chance of dying early.
- 02
Eating more polyunsaturated fat was linked to 21% lower chance of dying early and 34% lower chance of dying from heart disease.
- 03
Plant-based monounsaturated fats were linked to 17% lower risk of early death.
- 04
Animal-based ones were not.
- 05
Trans fats showed a small 4% higher risk per small increase.
- 06
Yes, the results suggest that choosing the right kinds of fat can make a meaningful difference in long-term health and lifespan.
Surprising findings
- Dietary fat intake showed no link to cancer death risk after adjustment.Many people believe eating red meat or saturated fat directly increases cancer risk, but this large study found no significant association with cancer mortality.
- Animal-based monounsaturated fats offered no survival benefit, unlike plant-based ones.The keto and carnivore diets often praise animal fats like tallow and lard as 'healthy MUFAs,' but this study found no longevity benefit.
Practical takeaways
Replace butter and red meat with nuts, seeds, avocados, and fatty fish to improve long-term heart health and longevity.
This is an observational study — it shows links, not proof that changing fats will directly extend life.
medium confidenceCheck ingredient labels and avoid partially hydrogenated oils, even in small amounts, due to the dose-dependent risk from trans fats.
Trans fat intake was low in this cohort, so the absolute risk increase is small, but cumulative exposure matters.
medium confidenceDon’t fear fat — just choose the right kinds. Focus on whole-food sources of PUFAs and plant-based MUFAs.
Dietary data came from self-reported questionnaires, which can be inaccurate due to memory bias.
medium confidenceWhy this study matters
The Fat That Kills Slowly
People who ate the most saturated fat had a 13% higher risk of dying during the study compared to those who ate the least. This link stayed strong even after adjusting for age, smoking, and other health factors.
Saturated fat is common in everyday foods like cheese, steak, and butter — choices many people make without thinking about long-term consequences.
The Super Fat That Slashes Heart Risk
Those who ate the most polyunsaturated fats (PUFAs) had a 34% lower risk of dying from heart disease and a 21% lower risk of early death overall. These fats come from foods like walnuts, flaxseeds, and fatty fish.
This is one of the strongest protective effects ever seen for a single dietary factor in large population studies.
Not All Olive Oil Is Equal — Source Matters
Plant-based monounsaturated fats (like in olives, avocados, and nuts) were linked to a 17% lower risk of early death, but animal-based MUFAs (like in bacon and beef fat) showed no benefit.
It’s not just about the fat type — where it comes from makes a huge difference, even if the molecule looks the same.
Trans Fats: The Tiny Killer
While trans fats didn’t show a clear risk in broad categories, every small increase in intake raised mortality risk by 4% per standard deviation — a 'dose matters' warning.
Even tiny amounts of industrial trans fats (in processed snacks and fried foods) may add up over time.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at what kinds of fat people eat and how long they live. It found that some fats are better than others.
Research results
Eating more saturated fat was linked to 13% higher chance of dying early. Eating more polyunsaturated fat was linked to 21% lower chance of dying early and 34% lower chance of dying from heart disease. Plant-based monounsaturated fats were linked to 17% lower risk of early death. Animal-based ones were not. Trans fats showed a small 4% higher risk per small increase.
What this means - more context
Yes, the results suggest that choosing the right kinds of fat can make a meaningful difference in long-term health and lifespan.
The study aimed to investigate the associations between dietary fat intake (saturated, trans, monounsaturated, and polyunsaturated fatty acids) and all-cause, cardiovascular, and cancer mortality in a large prospective cohort of US adults aged 55–74 years.
Higher intake of saturated fats was linked to increased all-cause mortality, while higher polyunsaturated and plant-based monounsaturated fat intake were associated with lower risks of all-cause and cardiovascular mortality. Animal-based monounsaturated fats showed no significant benefit, and none of the fats were significantly linked to cancer mortality after adjustment. Trans fat intake showed a small dose-dependent increase in mortality risk.
Methods Used
The study analyzed data from 101,832 participants in the PLCO cancer screening trial, aged 55–74, followed for a median of 17 years. Dietary intake was assessed using a food frequency questionnaire, and associations with mortality were evaluated using multivariable Cox regression models adjusted for confounders.
Main Finding
SFA intake was associated with a 13% higher risk of all-cause mortality (HR Q5 vs Q1 = 1.13, 95% CI 1.05–1.22). PUFA intake was associated with a 21% lower risk of all-cause mortality (HR = 0.79) and a 34% lower risk of CVD mortality (HR = 0.66). Plant-based MUFAs were associated with a 17% lower risk of all-cause and CVD mortality, while animal-based MUFAs were not. TFA intake showed a 4% increased risk per SD in continuous analysis, but not in categorical.
Confidence Level
The study has high sample size and long follow-up, uses validated dietary assessment, and reports adjusted hazard ratios with confidence intervals. However, as an observational study relying on self-reported diet data, residual confounding and measurement error are possible limitations.
Study Flags
Red Flags
- •Dietary data based on self-reported food frequency questionnaire, prone to recall bias
- •Observational design limits causal inference
- •Residual confounding possible despite multivariable adjustment
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Dietary fat intake showed no link to cancer death risk after adjustment.
Many people believe eating red meat or saturated fat directly increases cancer risk, but this large study found no significant association with cancer mortality.
Practical Takeaways
Replace butter and red meat with nuts, seeds, avocados, and fatty fish to improve long-term heart health and longevity.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 552 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Human Cohort Study
Subject
Moderate probability
on the GRADE evidence scale
This study watched a big group of people for many years to see how their diet relates to their chances of dying. It found links between certain fats and death risk, but it can't prove that the fats caused the changes — other lifestyle factors might be involved.
Strengths
- Large sample size (n = 101,832)
- Long follow-up duration (median 17 years)
- High number of outcome events (24,141 deaths)
Weaknesses
- Observational design – cannot prove causation
- Dietary data based on self-reported food frequency questionnaire (potential for misreporting)
- Single baseline dietary measurement (no updates over time)
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at what kinds of fat people eat and how long they live. It found that some fats are better than others.
Research results
Eating more saturated fat was linked to 13% higher chance of dying early. Eating more polyunsaturated fat was linked to 21% lower chance of dying early and 34% lower chance of dying from heart disease. Plant-based monounsaturated fats were linked to 17% lower risk of early death. Animal-based ones were not. Trans fats showed a small 4% higher risk per small increase.
What this means - more context
Yes, the results suggest that choosing the right kinds of fat can make a meaningful difference in long-term health and lifespan.
The study aimed to investigate the associations between dietary fat intake (saturated, trans, monounsaturated, and polyunsaturated fatty acids) and all-cause, cardiovascular, and cancer mortality in a large prospective cohort of US adults aged 55–74 years.
Higher intake of saturated fats was linked to increased all-cause mortality, while higher polyunsaturated and plant-based monounsaturated fat intake were associated with lower risks of all-cause and cardiovascular mortality. Animal-based monounsaturated fats showed no significant benefit, and none of the fats were significantly linked to cancer mortality after adjustment. Trans fat intake showed a small dose-dependent increase in mortality risk.
Methods Used
The study analyzed data from 101,832 participants in the PLCO cancer screening trial, aged 55–74, followed for a median of 17 years. Dietary intake was assessed using a food frequency questionnaire, and associations with mortality were evaluated using multivariable Cox regression models adjusted for confounders.
Main Finding
SFA intake was associated with a 13% higher risk of all-cause mortality (HR Q5 vs Q1 = 1.13, 95% CI 1.05–1.22). PUFA intake was associated with a 21% lower risk of all-cause mortality (HR = 0.79) and a 34% lower risk of CVD mortality (HR = 0.66). Plant-based MUFAs were associated with a 17% lower risk of all-cause and CVD mortality, while animal-based MUFAs were not. TFA intake showed a 4% increased risk per SD in continuous analysis, but not in categorical.
Confidence Level
The study has high sample size and long follow-up, uses validated dietary assessment, and reports adjusted hazard ratios with confidence intervals. However, as an observational study relying on self-reported diet data, residual confounding and measurement error are possible limitations.
Study Flags
Red Flags
- •Dietary data based on self-reported food frequency questionnaire, prone to recall bias
- •Observational design limits causal inference
- •Residual confounding possible despite multivariable adjustment
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Dietary fat intake showed no link to cancer death risk after adjustment.
Many people believe eating red meat or saturated fat directly increases cancer risk, but this large study found no significant association with cancer mortality.
Practical Takeaways
Replace butter and red meat with nuts, seeds, avocados, and fatty fish to improve long-term heart health and longevity.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 552 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Human Cohort Study
Subject
Moderate probability
on the GRADE evidence scale
This study watched a big group of people for many years to see how their diet relates to their chances of dying. It found links between certain fats and death risk, but it can't prove that the fats caused the changes — other lifestyle factors might be involved.
Strengths
- Large sample size (n = 101,832)
- Long follow-up duration (median 17 years)
- High number of outcome events (24,141 deaths)
Weaknesses
- Observational design – cannot prove causation
- Dietary data based on self-reported food frequency questionnaire (potential for misreporting)
- Single baseline dietary measurement (no updates over time)
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study is well-done because it followed lots of people for a long time and asked detailed questions about their health and diet. However, since it didn’t randomly assign diets, we can’t say for sure that the fats themselves caused the differences in health.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
38 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=101832)+20/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 552 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
This design cannot establish causation — the findings describe an association, not a cause. This is an observational cohort study; it cannot establish causation due to potential residual confounding, lack of randomization, and inability to control all variables. The study design only allows for identification of associations.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Thomas DeLauer cite this study, drawing 1 claim from it.