Study analysis · The journal of nutrition, health & aging · 2020
Most older men are eating dangerously little protein—and this 10-year study links it to a higher risk of dying, especially from cancer.
Older men who ate less protein were more likely to die over 10 years, with the strongest link for cancer deaths.
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 is like following a big group of older men for 10 years to see what they ate and who passed away. It found that men who ate less protein were more likely to die, but it can't prove that eating less protein caused it—maybe the men who ate less protein were already sicker or had other habits. So we can only say that eating less protein is linked to a higher chance of dying, not that it's the reason.
What’s the bottom line?
Researchers asked 5,790 older men about what they ate, then checked 10 years later to see who died. They found that men who ate less protein were more likely to die, especially from cancer.
How strong is this study?
The study was pretty well done because it followed many men for a long time and made adjustments for things like age, smoking, and exercise. But it's not a perfect experiment—people had to remember what they ate, and the study only included older white men, so the results might not apply to everyone.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
38 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=5790)+20/20
- Follow-up+10/10
100 / 100
54 / 100
- P-valuesno p-values reported
- 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 555 / 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 prospective cohort study. It cannot establish causation because there is no randomization, and the relationship between protein intake and mortality may be affected by residual confounding, reverse causation, measurement error in dietary intake, and other unmeasured factors. The observed associations do not prove that low protein intake causes higher mortality.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding disclosures were present in the provided text.
The provided text does not include a Conflict of Interest or Funding section. The study is from the MrOS cohort, but funding details are not provided in this excerpt. The text ends abruptly in the Discussion section.
Key takeaways
- 01
Men with lower protein intake had about a 9% higher risk of dying during the study for each 2.9% of daily energy decrease in protein.
- 02
Those who ate less than the recommended amount (0.8 g per kg of body weight) had a 58% higher risk of dying from cancer than those who ate more.
- 03
This is a meaningful difference for older men, but because this type of study can't prove cause and effect, we can't say for sure that low protein itself causes death.
Surprising findings
- Most older men in this study did not meet the RDA for protein—57.5% were below 0.8 g/kg/day.We often think of protein deficiency as rare in wealthy countries, but among older adults it's common, likely due to reduced appetite, food access, or dental issues.
- Lower protein intake was significantly associated with cancer mortality but not cardiovascular mortality.Heart disease is usually the biggest diet-sensitive killer, yet here the cancer link was stronger and more consistent, while CVD fell just short of statistical significance (HR=1.08, 95% CI 0.99-1.18).
- There was virtually no difference in mortality risk between dairy, non-dairy animal, and plant protein sources.Many studies show health differences based on protein source (e.g., red meat vs fish), but this study found all sources showed similar inverse associations with mortality.
Practical takeaways
If you're over 65, aim for at least 1.0 gram of protein per kilogram of body weight per day. For example, a 70 kg (154 lb) man needs about 70 grams of protein daily—roughly 3-4 servings of protein-rich foods (e.g., 1 cup of Greek yogurt, 4 oz of chicken, or 1 cup of lentils).
If you have kidney disease, consult a doctor first, as high protein intake can be harmful. Also, this study is observational, so we can't be certain low protein causes death—but the link is strong enough to be cautious.
Medium confidenceSpread protein across all meals—breakfast, lunch, and dinner—rather than eating it all at dinner. This helps with absorption and muscle building, though this study didn't assess timing, it's a low-risk strategy.
The study measured total daily intake, not meal timing, so the timing advice is based on other research, not this specific study.
Low confidenceDon't fixate on protein source—just get enough total protein. Mix animal and plant sources (meat, dairy, beans, nuts) to meet your daily target.
This study found similar associations for all sources, but it doesn't mean you should ignore other health effects of red meat or processed meats. Balance overall dietary quality.
Medium confidenceWhy this study matters
The Hidden Protein Deficiency Epidemic
In this study of 5,790 community-dwelling older men, 57.5% had protein intake below the recommended dietary allowance (RDA) of 0.8 g/kg/day. The average intake was just 0.79 g/kg/day, meaning most were below the baseline guideline.
Most people assume older adults get enough food and protein, but this data shows the majority are falling short, which may accelerate muscle loss, frailty, and mortality.
All Protein Sources Count Equally
Each 2.9% decrease in calories from dairy protein, non-dairy animal protein, or plant protein was associated with an 8-9% higher risk of all-cause mortality. Source mattered little—total intake mattered most.
This contradicts the common debate over animal vs plant protein. For older men, the primary issue is quantity, not source.
The Cancer Link That Should Scare You
Men who ate below the RDA had a 58% higher risk of dying from cancer (HR=1.58, 95% CI 1.12-2.23) compared to those eating ≥1.0 g/kg/day. For every 2.9% decrease in protein calories, cancer mortality rose by 13% (HR=1.13, 95% CI 1.03-1.25).
This is one of the strongest specific associations between a modifiable dietary factor and cancer death in older adults, potentially tied to immune function or tumor biology.
The RDA Is Probably Too Low for Seniors
The authors note that some professional societies recommend 1.0 g/kg/day for older adults. In this study, men eating below the RDA had worse outcomes, especially for cancer, than those eating ≥1.0 g/kg/day.
Official guidelines may be inadequate for the aging population, and simple dietary changes could have a meaningful impact on longevity.
The Age Paradox: Protein Flips Its Effect
In younger and middle-aged populations, high protein intake (especially animal protein) has been linked to higher mortality. Yet in this older cohort, higher protein intake was protective—supporting the idea that the association reverses with age.
It's a counterintuitive message: the same nutrient that might be risky at 40 may be life-saving at 75.
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
Researchers asked 5,790 older men about what they ate, then checked 10 years later to see who died. They found that men who ate less protein were more likely to die, especially from cancer.
Research results
Men with lower protein intake had about a 9% higher risk of dying during the study for each 2.9% of daily energy decrease in protein. Those who ate less than the recommended amount (0.8 g per kg of body weight) had a 58% higher risk of dying from cancer than those who ate more.
What this means - more context
This is a meaningful difference for older men, but because this type of study can't prove cause and effect, we can't say for sure that low protein itself causes death.
To determine whether total protein intake or protein from dairy, non-dairy animal, or plant sources is associated with all-cause and cause-specific mortality among older community-dwelling men.
In 5,790 men (mean age 73.6 years) followed up to 10 years, each 2.9% of energy decrease in total protein intake was associated with a 9% increased risk of all-cause mortality (adjusted HR 1.09, 95% CI 1.04-1.14). Similar associations were seen for dairy, non-dairy animal, and plant protein. Cancer mortality was significantly higher (HR 1.13, 95% CI 1.03-1.25), while cardiovascular mortality was not significantly associated (HR 1.08, 95% CI 0.99-1.18). Men consuming <0.8 g/kg/day had a 58% higher risk of cancer death than those consuming ≥1.0 g/kg/day.
Methods Used
Prospective cohort study (MrOS) of 5,790 ambulatory community-dwelling U.S. men aged ≥65 years. Protein intake (total and by source) was measured using a 69-item Block food frequency questionnaire at baseline; death outcomes were adjudicated over up to 10 years. Cox proportional hazards models adjusted for age, center, education, race, smoking, alcohol, physical activity, weight, total energy intake, and comorbidities.
Main Finding
Lower total protein intake was associated with modestly increased risk of all-cause and cancer mortality, but not cardiovascular mortality; associations did not differ by protein source.
Confidence Level
Moderate: large prospective cohort with long follow-up and comprehensive confounder adjustment, but reliance on a single FFQ and potential residual confounding.
Study Flags
Red Flags
- •Self-reported dietary intake via single FFQ may lead to misclassification
- •Observational design cannot exclude residual confounding
- •Cohort is predominantly non-Hispanic white men, limiting generalizability
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
Most older men in this study did not meet the RDA for protein—57.5% were below 0.8 g/kg/day.
We often think of protein deficiency as rare in wealthy countries, but among older adults it's common, likely due to reduced appetite, food access, or dental issues.
Practical Takeaways
If you're over 65, aim for at least 1.0 gram of protein per kilogram of body weight per day. For example, a 70 kg (154 lb) man needs about 70 grams of protein daily—roughly 3-4 servings of protein-rich foods (e.g., 1 cup of Greek yogurt, 4 oz of chicken, or 1 cup of lentils).
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 555 / 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 is like following a big group of older men for 10 years to see what they ate and who passed away. It found that men who ate less protein were more likely to die, but it can't prove that eating less protein caused it—maybe the men who ate less protein were already sicker or had other habits. So we can only say that eating less protein is linked to a higher chance of dying, not that it's the reason.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Large prospective cohort (n=5790) with 10-year follow-up and 1611 adjudicated deaths.
- Adjustment for multiple potential confounders including age, center, education, race, smoking, alcohol, physical activity, weight, total energy intake, and comorbidities.
- Assessment of protein intake by source (dairy, non-dairy animal, plant) using a standardized unit (per 2.9% TEI).
Weaknesses
- Observational design precludes causal inference.
- Dietary intake measured with a self-reported food frequency questionnaire at a single time point, prone to measurement error and misclassification.
- Potential residual confounding from unmeasured or imperfectly measured variables.
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Researchers asked 5,790 older men about what they ate, then checked 10 years later to see who died. They found that men who ate less protein were more likely to die, especially from cancer.
Research results
Men with lower protein intake had about a 9% higher risk of dying during the study for each 2.9% of daily energy decrease in protein. Those who ate less than the recommended amount (0.8 g per kg of body weight) had a 58% higher risk of dying from cancer than those who ate more.
What this means - more context
This is a meaningful difference for older men, but because this type of study can't prove cause and effect, we can't say for sure that low protein itself causes death.
To determine whether total protein intake or protein from dairy, non-dairy animal, or plant sources is associated with all-cause and cause-specific mortality among older community-dwelling men.
In 5,790 men (mean age 73.6 years) followed up to 10 years, each 2.9% of energy decrease in total protein intake was associated with a 9% increased risk of all-cause mortality (adjusted HR 1.09, 95% CI 1.04-1.14). Similar associations were seen for dairy, non-dairy animal, and plant protein. Cancer mortality was significantly higher (HR 1.13, 95% CI 1.03-1.25), while cardiovascular mortality was not significantly associated (HR 1.08, 95% CI 0.99-1.18). Men consuming <0.8 g/kg/day had a 58% higher risk of cancer death than those consuming ≥1.0 g/kg/day.
Methods Used
Prospective cohort study (MrOS) of 5,790 ambulatory community-dwelling U.S. men aged ≥65 years. Protein intake (total and by source) was measured using a 69-item Block food frequency questionnaire at baseline; death outcomes were adjudicated over up to 10 years. Cox proportional hazards models adjusted for age, center, education, race, smoking, alcohol, physical activity, weight, total energy intake, and comorbidities.
Main Finding
Lower total protein intake was associated with modestly increased risk of all-cause and cancer mortality, but not cardiovascular mortality; associations did not differ by protein source.
Confidence Level
Moderate: large prospective cohort with long follow-up and comprehensive confounder adjustment, but reliance on a single FFQ and potential residual confounding.
Study Flags
Red Flags
- •Self-reported dietary intake via single FFQ may lead to misclassification
- •Observational design cannot exclude residual confounding
- •Cohort is predominantly non-Hispanic white men, limiting generalizability
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
Most older men in this study did not meet the RDA for protein—57.5% were below 0.8 g/kg/day.
We often think of protein deficiency as rare in wealthy countries, but among older adults it's common, likely due to reduced appetite, food access, or dental issues.
Practical Takeaways
If you're over 65, aim for at least 1.0 gram of protein per kilogram of body weight per day. For example, a 70 kg (154 lb) man needs about 70 grams of protein daily—roughly 3-4 servings of protein-rich foods (e.g., 1 cup of Greek yogurt, 4 oz of chicken, or 1 cup of lentils).
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 555 / 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 is like following a big group of older men for 10 years to see what they ate and who passed away. It found that men who ate less protein were more likely to die, but it can't prove that eating less protein caused it—maybe the men who ate less protein were already sicker or had other habits. So we can only say that eating less protein is linked to a higher chance of dying, not that it's the reason.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Large prospective cohort (n=5790) with 10-year follow-up and 1611 adjudicated deaths.
- Adjustment for multiple potential confounders including age, center, education, race, smoking, alcohol, physical activity, weight, total energy intake, and comorbidities.
- Assessment of protein intake by source (dairy, non-dairy animal, plant) using a standardized unit (per 2.9% TEI).
Weaknesses
- Observational design precludes causal inference.
- Dietary intake measured with a self-reported food frequency questionnaire at a single time point, prone to measurement error and misclassification.
- Potential residual confounding from unmeasured or imperfectly measured variables.
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study was pretty well done because it followed many men for a long time and made adjustments for things like age, smoking, and exercise. But it's not a perfect experiment—people had to remember what they ate, and the study only included older white men, so the results might not apply to everyone.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
38 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=5790)+20/20
- Follow-up+10/10
100 / 100
54 / 100
- P-valuesno p-values reported
- 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 555 / 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 prospective cohort study. It cannot establish causation because there is no randomization, and the relationship between protein intake and mortality may be affected by residual confounding, reverse causation, measurement error in dietary intake, and other unmeasured factors. The observed associations do not prove that low protein intake causes higher mortality.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding disclosures were present in the provided text.
The provided text does not include a Conflict of Interest or Funding section. The study is from the MrOS cohort, but funding details are not provided in this excerpt. The text ends abruptly in the Discussion section.