Potentially true Certainty of evidence: low provisional C-SUP-07

Certain supplements caused specific harms: more hip fractures (vitamin A), kidney stones (vitamin C), falls and fractures (high-dose vitamin D), type 2 diabetes (selenium), and no benefit for knee pain (glucosamine).

Conclusion: Possibly true for specific high-dose regimens; not a general verdict on supplements.

Original statement
Scientific assessment
In plain language
Studies on this claim
Regional context
What applies in my country?
References

Original statement

حين أُخضعت المكملات الفموية الأكثر مبيعاً — من الكالسيوم والبيتا كاروتين وفيتامين E، إلى أوميغا-3 والمتعددات والجلوكوزامين والسيلينيوم وفيتامين A — لاختبارات عشوائية مضبوطة بالغفل وبأحجام كبيرة ومتابعة طويلة، لم تَفِ في الغالب بوعودها؛ بل أن بعضها أحدث ضرراً صريحاً: زيادة في الوفيات، وفي سرطان الرئة والبروستاتا، وفي احتشاء عضلة القلب، وفي الرجفان الأذيني، وفي كسور الورك، وفي حصى الكلى. ما يُسوَّق على أنه «وقاية» انقلب في عدة تجارب إلى مصدر للأذى.

not verbatim – paraphrase. Translation by the project; the Arabic wording is authoritative.

Translation

Certain supplements caused specific harms: more hip fractures (vitamin A), kidney stones (vitamin C), falls and fractures (high-dose vitamin D), type 2 diabetes (selenium), and no benefit for knee pain (glucosamine).

Origin

Source status: Archive editors
Attribution: Archive editors (eltayebat.com); not verified as Elawady's own words
Origin: https://eltayebat.com/rule/oral-supplements/
Attribution uncertainty: Written by the archive operators; study selection is the archive's, not necessarily Elawady's.

Claimed mechanism: Dose-specific toxicity.
Claimed health effect: Fractures, kidney stones, falls, diabetes.
Population concerned: Various.
Geographic restriction by Elawady: none found

Scientific assessment

Potentially true – Some evidence points in favour of the statement, but it is not sufficient for a clear judgement.

Certainty of evidence: low – Further research is likely to change the assessment considerably.

1. What was claimed?

Several supplements caused fractures, kidney stones, falls and diabetes.

2. What is demonstrably correct?

Sanders 2010: fracture RR 1.26 (1.00–1.59), falls RR 1.15 with annual 500,000 IU; Bischoff-Ferrari 2016: more falls with 60,000 IU monthly; Stranges 2007: diabetes HR 1.55 (1.03–2.33) with selenium; Feskanich 2002: hip fracture RR 1.48 for highest vitamin A intake (retinol 1.89); GAIT: glucosamine not better than placebo overall.

3. What is wrong or exaggerated?

The summary generalises dose-specific findings (huge boluses, high retinol) to 'supplements' in general. Vitamin A and vitamin C findings are observational. VITAL (daily 2,000 IU vitamin D) found no excess adverse events.

4. What remains unclear?

The vitamin C kidney-stone letter (Thomas 2013) has no abstract in PubMed and could not be checked here.

5. Which studies support it?

A-SUP-14, A-SUP-15, A-SUP-16, A-SUP-20, A-SUP-21, A-SUP-13.

6. Which studies contradict it?

A-SUP-22 (VITAL: no excess hypercalcaemia or adverse events); Endocrine Society 2024 (I-SUP-05) prefers daily over intermittent high doses.

7. What applies to Germany and Europe?

Applies equally.

8. What is known about Egypt?

Applies equally.

9. What practical conclusion is appropriate?

Avoid very high or intermittent mega-doses and high-dose retinol; moderate daily doses for a clear indication are a different matter.

Assessment details

Rationale for certainty of evidence: Evidence is mixed in quality: annual 500,000 IU vitamin D increased falls and fractures in an RCT; monthly 60,000 IU increased falls versus 24,000 IU in a small RCT; selenium increased diabetes as a secondary outcome of one RCT; vitamin A/hip fracture and vitamin C/kidney stones come from observational data; GAIT found no overall benefit of glucosamine. USPSTF 2022 called the evidence for these harms 'limited'.
Source quality: Correct citations; harms are regimen- and dose-specific.
Regional transferability: High.
Individual exceptions: Daily moderate-dose vitamin D in deficient people is a different situation from large intermittent boluses.
Regional scope of the claim: general (biological/medical)
Last reviewed: 25 October 2026 provisional

In plain language

Some trials found harm from very large doses: a single huge yearly dose of vitamin D increased falls and fractures in older women, and selenium pills may have raised diabetes. Other links, such as vitamin A with hip fractures, come from observational studies. These results warn against mega-doses, not against every vitamin pill.

Studies on this claim

Studies supporting the claim (5)

Yearly vitamin D mega-dose

Sanders KM et al.. JAMA 2010 · PMID 20460620 · DOI 10.1001/jama.2010.594

Randomised controlled trialcited by the Tayebat archiveabstract only checked

More falls and fractures with 500,000 IU once a year.

Does the study support the specific claim? Yes · Methodological quality: high · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Falls prevention.
How was the study done?
RCT.
How many people, animals or samples were studied?
2,256 women.
What was actually found?
More falls and fractures.
How large was the observed effect?
RR 1.15; 1.26.
What do the results mean in everyday life?
Avoid mega-doses.
What are the study's limitations?
Regimen-specific.
What does it say about Elawady's specific claim?
Supports for this regimen.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Daily doses.
Scientific details →
High monthly vitamin D and falls

Bischoff-Ferrari HA et al.. JAMA Intern Med 2016 · PMID 26747333 · DOI 10.1001/jamainternmed.2015.7148

Randomised controlled trialcited by the Tayebat archiveabstract only checked

More people fell with the higher monthly doses.

Does the study support the specific claim? Partly · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Function and falls.
How was the study done?
RCT.
How many people, animals or samples were studied?
200.
What was actually found?
More falls.
How large was the observed effect?
67% vs 48%.
What do the results mean in everyday life?
Avoid high boluses.
What are the study's limitations?
Small.
What does it say about Elawady's specific claim?
Partly supports.
Do the results apply to Germany and Europe?
Swiss.
What can explicitly not be concluded from this study?
Daily doses.
Scientific details →
Selenium and diabetes

Stranges S et al.. Ann Intern Med 2007 · PMID 17620655 · DOI 10.7326/0003-4819-147-4-200708210-00175

Randomised controlled trialcited by the Tayebat archiveabstract only checked

Selenium pills were linked to more new diabetes (HR 1.55).

Does the study support the specific claim? Partly · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Diabetes with selenium.
How was the study done?
RCT secondary analysis.
How many people, animals or samples were studied?
1,202.
What was actually found?
More diabetes.
How large was the observed effect?
HR 1.55.
What do the results mean in everyday life?
Avoid selenium pills.
What are the study's limitations?
Secondary outcome.
What does it say about Elawady's specific claim?
Partly supports.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Firm harm.
Scientific details →
Vitamin A and hip fractures

Feskanich D et al.. JAMA 2002 · PMID 11754708 · DOI 10.1001/jama.287.1.47

Cohort studycited by the Tayebat archiveabstract only checked

Women with the highest retinol intake had about 1.9 times the risk of hip fracture.

Does the study support the specific claim? Partly · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Retinol and fractures.
How was the study done?
Cohort.
How many people, animals or samples were studied?
72,337.
What was actually found?
More fractures with high retinol.
How large was the observed effect?
RR 1.89.
What do the results mean in everyday life?
Avoid high retinol.
What are the study's limitations?
Observational.
What does it say about Elawady's specific claim?
Partly supports.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Causation.
Scientific details →
Glucosamine for knee pain (GAIT)

Clegg DO et al.. N Engl J Med 2006 · PMID 16495392 · DOI 10.1056/NEJMoa052771

Randomised controlled trialcited by the Tayebat archiveabstract only checked

Not better than placebo overall.

Does the study support the specific claim? Yes · Methodological quality: high · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Knee OA pain.
How was the study done?
RCT.
How many people, animals or samples were studied?
1,583.
What was actually found?
No overall benefit.
How large was the observed effect?
+3.9 points n.s.
What do the results mean in everyday life?
Little benefit.
What are the study's limitations?
Subgroup.
What does it say about Elawady's specific claim?
Supports.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Harm.
Scientific details →

Studies contradicting or limiting the claim (2)

VITAL: vitamin D for prevention

Manson JE et al.. N Engl J Med 2019 · PMID 30415629 · DOI 10.1056/NEJMoa1809944

Randomised controlled trialcited by the Tayebat archiveabstract only checked

No prevention of cancer or heart disease; no safety problems.

Does the study support the specific claim? Yes · Methodological quality: high · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Prevention.
How was the study done?
RCT.
How many people, animals or samples were studied?
25,871.
What was actually found?
Null.
How large was the observed effect?
HR 0.96/0.97.
What do the results mean in everyday life?
No need in replete adults.
What are the study's limitations?
Replete population.
What does it say about Elawady's specific claim?
Supports C-SUP-01.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Effect in deficiency.
Scientific details →
Endocrine Society 2024 vitamin D guideline

Demay MB et al.. J Clin Endocrinol Metab 2024 · PMID 38828931 · DOI 10.1210/clinem/dgae290

Guideline / position statementindependent cross-checkabstract only checked

Suggests vitamin D for children, pregnancy, people ≥75 and high-risk prediabetes.

Does the study support the specific claim? No · Methodological quality: high · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Vitamin D for prevention.
How was the study done?
Guideline.
What was actually found?
Group-specific suggestions.
What do the results mean in everyday life?
Some groups benefit.
What are the study's limitations?
Conditional.
What does it say about Elawady's specific claim?
Contradicts blanket ban.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Doses.
Scientific details →

Studies with mixed or unclear results (2)

Vitamin C pills and kidney stones

Thomas LD et al.. JAMA Intern Med 2013 · PMID 23381591 · DOI 10.1001/jamainternmed.2013.2296

Cohort studycited by the Tayebat archiveabstract only checked

Not read (no abstract).

Does the study support the specific claim? Unclear · Methodological quality: low · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Kidney stones and vitamin C.
How was the study done?
Cohort letter.
How many people, animals or samples were studied?
Not read.
What was actually found?
Not read.
How large was the observed effect?
Not read.
What are the study's limitations?
No abstract.
What does it say about Elawady's specific claim?
Cannot judge.
What can explicitly not be concluded from this study?
Anything specific.
Scientific details →
HOPE-2: B vitamins in vascular disease

Lonn E et al.. N Engl J Med 2006 · PMID 16531613 · DOI 10.1056/NEJMoa060900

Randomised controlled trialcited by the Tayebat archiveabstract only checked

No reduction in major CV events; fewer strokes.

Does the study support the specific claim? Partly · Methodological quality: high · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
CV prevention.
How was the study done?
RCT.
How many people, animals or samples were studied?
5,522.
What was actually found?
Null primary.
How large was the observed effect?
RR 0.95.
What do the results mean in everyday life?
Not for CV prevention.
What does it say about Elawady's specific claim?
Mixed.
Do the results apply to Germany and Europe?
Applicable.
Scientific details →

Regional context

Germany / EU

Applies equally.

Egypt

Applies equally.

What applies in my country?

General scientific assessment

Potentially true Possibly true for specific high-dose regimens; not a general verdict on supplements.

This statement concerns biological or medical relationships. The scientific assessment above applies regardless of the country; country-specific food data do not change it.

References

Annual high-dose oral vitamin D and falls and fractures in older women: a randomized controlled trial.. Sanders KM et al.. JAMA 2010 · PMID 20460620 · DOI 10.1001/jama.2010.594
Monthly High-Dose Vitamin D Treatment for the Prevention of Functional Decline: A Randomized Clinical Trial.. Bischoff-Ferrari HA et al.. JAMA Intern Med 2016 · PMID 26747333 · DOI 10.1001/jamainternmed.2015.7148
Effects of long-term selenium supplementation on the incidence of type 2 diabetes: a randomized trial.. Stranges S et al.. Ann Intern Med 2007 · PMID 17620655 · DOI 10.7326/0003-4819-147-4-200708210-00175
Vitamin A intake and hip fractures among postmenopausal women.. Feskanich D et al.. JAMA 2002 · PMID 11754708 · DOI 10.1001/jama.287.1.47
Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis.. Clegg DO et al.. N Engl J Med 2006 · PMID 16495392 · DOI 10.1056/NEJMoa052771
Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease.. Manson JE et al.. N Engl J Med 2019 · PMID 30415629 · DOI 10.1056/NEJMoa1809944
Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline.. Demay MB et al.. J Clin Endocrinol Metab 2024 · PMID 38828931 · DOI 10.1210/clinem/dgae290
Ascorbic acid supplements and kidney stone incidence among men: a prospective study.. Thomas LD et al.. JAMA Intern Med 2013 · PMID 23381591 · DOI 10.1001/jamainternmed.2013.2296
Homocysteine lowering with folic acid and B vitamins in vascular disease.. Lonn E et al.. N Engl J Med 2006 · PMID 16531613 · DOI 10.1056/NEJMoa060900

← Back to overview

Certain supplements caused specific harms: more hip fractures (vitamin A), kidney stones (vitamin C), falls and fractures (high-dose vitamin D), type 2 diabetes (selenium), and no benefit for knee pain (glucosamine).

Original statement

Translation

Origin

Scientific assessment

1. What was claimed?

2. What is demonstrably correct?

3. What is wrong or exaggerated?

4. What remains unclear?

5. Which studies support it?

6. Which studies contradict it?

7. What applies to Germany and Europe?

8. What is known about Egypt?

9. What practical conclusion is appropriate?

Assessment details

In plain language

Studies on this claim

Studies supporting the claim (5)

Yearly vitamin D mega-dose

High monthly vitamin D and falls

Selenium and diabetes

Vitamin A and hip fractures

Glucosamine for knee pain (GAIT)

Studies contradicting or limiting the claim (2)

VITAL: vitamin D for prevention

Endocrine Society 2024 vitamin D guideline

Studies with mixed or unclear results (2)

Vitamin C pills and kidney stones

HOPE-2: B vitamins in vascular disease

Regional context

Germany / EU

Egypt

What applies in my country?

General scientific assessment

References