Study analysis · The American journal of clinical nutrition · 2021
Vegan women are 55% more likely to break a hip – but a daily calcium and vitamin D supplement erases the risk entirely.
A study of over 34,000 people found that vegan women who don't take calcium and vitamin D supplements have a much higher risk of hip fracture, but taking both supplements brings their risk down to the same as meat-eaters.
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 about 8 years to see who got broken hips and what they ate. It found that women who ate only plants (vegan) had more breaks, but when they took extra vitamin D and calcium, they had the same number of breaks as others. This study is like noticing that people who do one thing also have another thing happen – it doesn't prove that eating plants causes the breaks, just that they often happen together.
What’s the bottom line?
This study followed over 34,000 adults for about 8 years to see if eating patterns affect the risk of breaking a hip. They compared vegans, vegetarians, and meat-eaters. They found that vegan women had more hip fractures than women who ate meat, but only if they did not take both calcium and vitamin D supplements. If vegan women took both supplements, their risk was the same as meat-eaters.
How strong is this study?
This study is pretty good because it followed many people for a long time and asked about their eating habits. But it's not perfect because people might not remember exactly what they ate, and there could be other reasons for the breaks. So we can't be absolutely sure that the eating caused the breaks, but it gives us a clue to explore more.
100 / 100
- COI disclosure+40/40
- Data availability+35/35
- Code availability+25/25
38 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=34542)+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 572 / 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 with no randomization or control group. Causation cannot be established because there may be unmeasured confounding variables, selection bias, and measurement error. The observed associations between dietary patterns and hip fracture risk are subject to alternative explanations, and the study does not provide evidence of a causal mechanism.
No Conflicts
No conflicts of interest identified
No conflicts of interest identified. The study was funded by the National Cancer Institute, a government agency, with no industry involvement.
Funders
The study is based on the Adventist Health Study 2 cohort, which may have selection bias due to the healthy lifestyle of Seventh-day Adventists, but this is not a conflict of interest.
Key takeaways
- 01
In this study, vegan women had a 55% higher chance of hip fracture than non-vegetarian women.
- 02
But vegan women who took both calcium and vitamin D had no higher risk.
- 03
Vegan women who took neither had almost 3 times the risk.
- 04
Men did not show this difference.
- 05
This is important because many people eat vegan diets for health or ethical reasons.
- 06
The study suggests that vegan women need to be careful to get enough calcium and vitamin D to protect their bones.
- 07
Taking both supplements together may make vegan diets as safe for bones as diets that include dairy and meat.
Surprising findings
- The excess hip fracture risk among vegan women completely disappeared when they took both calcium and vitamin D supplements (HR 0.84, 95% CI 0.42-1.66).This suggests that the risk is not inherent to the vegan diet but rather due to specific nutrient deficiencies that can be easily corrected.
- Vegan women who took no calcium or vitamin D supplements had nearly 3 times the hip fracture risk (HR 2.99) compared to nonvegetarians.A near tripling of risk is substantial and underscores the importance of these nutrients in bone health.
- The association between diet and hip fracture was only seen in women, not men.Many studies find sex differences, but this stark contrast suggests a gender-specific vulnerability that is not often highlighted in plant-based diet discussions.
Practical takeaways
If you're a vegan woman over 45, consider taking a combined calcium and vitamin D supplement to protect your hip bone health.
Consult with a healthcare provider before starting any supplement, as excessive calcium intake may have risks.
medium-high (observational but large and well-conducted) confidenceVegans should monitor their dietary intake of calcium and vitamin D, and consider fortified foods like plant milks and breakfast cereals.
Food sources may not provide enough; sunlight exposure also matters for vitamin D synthesis.
high (nutrient shortfalls are well-documented) confidenceHealthcare providers should discuss bone health with vegan patients, especially women, and evaluate the need for supplementation.
Individual risk factors like age, BMI, and fracture history should guide decisions.
medium (based on one study, but corroborated by other research) confidenceWhy this study matters
The vegan hip fracture risk
In a large prospective study with over 34,000 non-Hispanic white adults, vegan women had a 55% higher risk of hip fracture (HR 1.55, 95% CI 1.06-2.26) compared to nonvegetarian women, after adjusting for lifestyle and nutrient intake.
Many people adopt vegan diets for health benefits, but this shows a hidden danger for bone health in women.
Supplements neutralize the risk
When vegan women took both calcium and vitamin D supplements, their hip fracture risk (HR 0.84, 95% CI 0.42-1.66) was no different from nonvegetarians. This suggests that the risk is due to nutrient deficiencies, not the diet itself.
This is empowering – it means a simple dietary supplement can eliminate the elevated risk.
The danger of skipping supplements
Vegan women who took neither calcium nor vitamin D supplements had nearly three times the hip fracture risk (HR 2.99, 95% CI 1.54-5.82) compared to nonvegetarians, highlighting the critical role of these nutrients.
The nearly 3-fold risk is dramatic and catches attention – it's a clear call to action for vegan women.
Why men are not affected
No significant association was found between dietary pattern and hip fracture risk in men (HR 1.01, 95% CI 0.61-1.68). This sex difference may be due to hormones, bone mass, or other biological factors.
It challenges the assumption that vegan diets affect all genders equally and sparks curiosity about sex-specific nutrition.
Key nutrient shortfalls in vegan diets
Vegans in this study consumed significantly less calcium (mean 788 mg/d vs 920 mg/d) and vitamin D (2.4 μg/d vs 4.9 μg/d) than nonvegetarians, and fewer took both supplements (32% vs ~50%).
This shows that even intentional plant-based eaters may miss out on bone-critical nutrients, which is a practical concern.
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 followed over 34,000 adults for about 8 years to see if eating patterns affect the risk of breaking a hip. They compared vegans, vegetarians, and meat-eaters. They found that vegan women had more hip fractures than women who ate meat, but only if they did not take both calcium and vitamin D supplements. If vegan women took both supplements, their risk was the same as meat-eaters.
Research results
In this study, vegan women had a 55% higher chance of hip fracture than non-vegetarian women. But vegan women who took both calcium and vitamin D had no higher risk. Vegan women who took neither had almost 3 times the risk. Men did not show this difference.
What this means - more context
This is important because many people eat vegan diets for health or ethical reasons. The study suggests that vegan women need to be careful to get enough calcium and vitamin D to protect their bones. Taking both supplements together may make vegan diets as safe for bones as diets that include dairy and meat.
To investigate whether dietary patterns (vegan, lacto-ovo-vegetarian, pesco-vegetarian, semivegetarian, nonvegetarian) are associated with hip fracture risk in a large North American cohort, and whether calcium and vitamin D supplementation modifies any association.
In a prospective cohort of 34,542 non-Hispanic white adults aged 45+ followed for a median of 8.4 years, vegan women had a 55% higher hip fracture risk than nonvegetarian women (HR 1.55, 95% CI 1.06-2.26). This elevated risk was confined to vegan women who did not take both calcium and vitamin D supplements; those taking both had risk similar to nonvegetarians (HR 0.84, 95% CI 0.42-1.66). No significant association was seen in men. The study concludes that vegan women without combined supplementation are at high risk, but supplementation may offset it.
Methods Used
Prospective cohort study (Adventist Health Study 2) with 34,542 non-Hispanic white women and men aged 45+ enrolled 2002-2007. Dietary patterns assessed via validated FFQ. Hip fractures self-reported via biennial questionnaires. Cox proportional hazards models adjusted for demographics, lifestyle, and nutrient intake (including calcium and vitamin D). Stratified analyses by supplement use (calcium only, vitamin D only, both, neither).
Main Finding
Female vegans had a 55% higher hip fracture risk than nonvegetarians (HR 1.55, 95% CI 1.06-2.26) in multivariable models. Among vegan women taking both calcium and vitamin D supplements, risk was similar to nonvegetarians (HR 0.84, 95% CI 0.42-1.66), while those taking neither had nearly 3-fold higher risk (HR 2.99, 95% CI 1.54-5.82). No significant association was observed in men (HR 1.01, 95% CI 0.61-1.68 for vegans vs. nonvegetarians).
Confidence Level
Moderate to high confidence. Large prospective cohort with validated dietary questionnaire, long follow-up, and adjustment for many confounders. Limitations include self-reported fractures, lack of serum vitamin D measurements, and limited power for some subgroup analyses (e.g., vitamin D alone). Residual confounding possible due to observational design.
Study Flags
Red Flags
- •Self-reported hip fractures without verification (though accuracy validated in previous studies).
- •No measurement of serum vitamin D levels; sun exposure estimated only by time outdoors and skin type.
- •No repeated dietary assessments, though dietary patterns in Adventists are stable.
Surprising Findings
The excess hip fracture risk among vegan women completely disappeared when they took both calcium and vitamin D supplements (HR 0.84, 95% CI 0.42-1.66).
This suggests that the risk is not inherent to the vegan diet but rather due to specific nutrient deficiencies that can be easily corrected.
Practical Takeaways
If you're a vegan woman over 45, consider taking a combined calcium and vitamin D supplement to protect your hip bone health.
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 572 / 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
High probability
on the GRADE evidence scale
This study watched a big group of people for about 8 years to see who got broken hips and what they ate. It found that women who ate only plants (vegan) had more breaks, but when they took extra vitamin D and calcium, they had the same number of breaks as others. This study is like noticing that people who do one thing also have another thing happen – it doesn't prove that eating plants causes the breaks, just that they often happen together.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Large prospective cohort (n=34,542) with long follow-up (median 8.4 years).
- Validated food frequency questionnaire for dietary assessment.
- Multiple imputation for missing data to reduce bias.
Weaknesses
- Observational design allows for residual confounding.
- Self-reported dietary intake and fracture outcomes may have measurement error.
- Single dietary assessment at baseline may not capture changes over time.
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study followed over 34,000 adults for about 8 years to see if eating patterns affect the risk of breaking a hip. They compared vegans, vegetarians, and meat-eaters. They found that vegan women had more hip fractures than women who ate meat, but only if they did not take both calcium and vitamin D supplements. If vegan women took both supplements, their risk was the same as meat-eaters.
Research results
In this study, vegan women had a 55% higher chance of hip fracture than non-vegetarian women. But vegan women who took both calcium and vitamin D had no higher risk. Vegan women who took neither had almost 3 times the risk. Men did not show this difference.
What this means - more context
This is important because many people eat vegan diets for health or ethical reasons. The study suggests that vegan women need to be careful to get enough calcium and vitamin D to protect their bones. Taking both supplements together may make vegan diets as safe for bones as diets that include dairy and meat.
To investigate whether dietary patterns (vegan, lacto-ovo-vegetarian, pesco-vegetarian, semivegetarian, nonvegetarian) are associated with hip fracture risk in a large North American cohort, and whether calcium and vitamin D supplementation modifies any association.
In a prospective cohort of 34,542 non-Hispanic white adults aged 45+ followed for a median of 8.4 years, vegan women had a 55% higher hip fracture risk than nonvegetarian women (HR 1.55, 95% CI 1.06-2.26). This elevated risk was confined to vegan women who did not take both calcium and vitamin D supplements; those taking both had risk similar to nonvegetarians (HR 0.84, 95% CI 0.42-1.66). No significant association was seen in men. The study concludes that vegan women without combined supplementation are at high risk, but supplementation may offset it.
Methods Used
Prospective cohort study (Adventist Health Study 2) with 34,542 non-Hispanic white women and men aged 45+ enrolled 2002-2007. Dietary patterns assessed via validated FFQ. Hip fractures self-reported via biennial questionnaires. Cox proportional hazards models adjusted for demographics, lifestyle, and nutrient intake (including calcium and vitamin D). Stratified analyses by supplement use (calcium only, vitamin D only, both, neither).
Main Finding
Female vegans had a 55% higher hip fracture risk than nonvegetarians (HR 1.55, 95% CI 1.06-2.26) in multivariable models. Among vegan women taking both calcium and vitamin D supplements, risk was similar to nonvegetarians (HR 0.84, 95% CI 0.42-1.66), while those taking neither had nearly 3-fold higher risk (HR 2.99, 95% CI 1.54-5.82). No significant association was observed in men (HR 1.01, 95% CI 0.61-1.68 for vegans vs. nonvegetarians).
Confidence Level
Moderate to high confidence. Large prospective cohort with validated dietary questionnaire, long follow-up, and adjustment for many confounders. Limitations include self-reported fractures, lack of serum vitamin D measurements, and limited power for some subgroup analyses (e.g., vitamin D alone). Residual confounding possible due to observational design.
Study Flags
Red Flags
- •Self-reported hip fractures without verification (though accuracy validated in previous studies).
- •No measurement of serum vitamin D levels; sun exposure estimated only by time outdoors and skin type.
- •No repeated dietary assessments, though dietary patterns in Adventists are stable.
Surprising Findings
The excess hip fracture risk among vegan women completely disappeared when they took both calcium and vitamin D supplements (HR 0.84, 95% CI 0.42-1.66).
This suggests that the risk is not inherent to the vegan diet but rather due to specific nutrient deficiencies that can be easily corrected.
Practical Takeaways
If you're a vegan woman over 45, consider taking a combined calcium and vitamin D supplement to protect your hip bone health.
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 572 / 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
High probability
on the GRADE evidence scale
This study watched a big group of people for about 8 years to see who got broken hips and what they ate. It found that women who ate only plants (vegan) had more breaks, but when they took extra vitamin D and calcium, they had the same number of breaks as others. This study is like noticing that people who do one thing also have another thing happen – it doesn't prove that eating plants causes the breaks, just that they often happen together.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Large prospective cohort (n=34,542) with long follow-up (median 8.4 years).
- Validated food frequency questionnaire for dietary assessment.
- Multiple imputation for missing data to reduce bias.
Weaknesses
- Observational design allows for residual confounding.
- Self-reported dietary intake and fracture outcomes may have measurement error.
- Single dietary assessment at baseline may not capture changes over time.
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
This study is pretty good because it followed many people for a long time and asked about their eating habits. But it's not perfect because people might not remember exactly what they ate, and there could be other reasons for the breaks. So we can't be absolutely sure that the eating caused the breaks, but it gives us a clue to explore more.
100 / 100
- COI disclosure+40/40
- Data availability+35/35
- Code availability+25/25
38 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=34542)+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 572 / 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 with no randomization or control group. Causation cannot be established because there may be unmeasured confounding variables, selection bias, and measurement error. The observed associations between dietary patterns and hip fracture risk are subject to alternative explanations, and the study does not provide evidence of a causal mechanism.
No Conflicts
No conflicts of interest identified
No conflicts of interest identified. The study was funded by the National Cancer Institute, a government agency, with no industry involvement.
Funders
The study is based on the Adventist Health Study 2 cohort, which may have selection bias due to the healthy lifestyle of Seventh-day Adventists, but this is not a conflict of interest.
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 Dr Brad Stanfield cite this study, drawing 1 claim from it.
- Contradicted
Evidence contradicts this claim.
Evidence