Nezam El-Tayebat Fact CheckA scientific assessment of the “نظام الطيبات” nutrition system
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Potentially true Overinterpreted Certainty of evidence: low provisional C-DRY-06

Milk intake raises circulating IGF-1, and higher IGF-1 increases prostate cancer risk; this is the mechanism behind the dairy-prostate cancer link ('the same hormone that makes a calf grow').

In short: Milk modestly raises IGF-1 and IGF-1 is probably a causal prostate cancer factor, but it is not shown that milk causes prostate cancer through this route; calling it 'the mechanism' overstates the evidence.
Conclusion: Milk modestly raises IGF-1 and IGF-1 is weakly linked to prostate cancer; this is a plausible but unproven mechanism, not proof of harm.
  1. Original statement
  2. Scientific assessment
  3. Scientific evidence in detail
  4. In plain language
  5. Studies on this claim
  6. Regional context
  7. What applies in my country?
  8. References

Original statement

مراجعة Cancer Causes & Control عام 2017 وثّقت أن شرب الحليب يرفع مستوى عامل النمو IGF-1 في الدم، وأن ارتفاع IGF-1 يزيد خطر سرطان البروستاتا — وهو نفس الهرمون الذي يجعل العجل ينمو بسرعة.

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

Translation

Milk intake raises circulating IGF-1, and higher IGF-1 increases prostate cancer risk; this is the mechanism behind the dairy-prostate cancer link ('the same hormone that makes a calf grow').

Origin

Source status
Archive editors
Attribution
Archive editors (eltayebat.com, rule 'dairy')
Origin
https://eltayebat.com/rule/dairy/
Attribution uncertainty
Editorial narrative and study selection by the archive operators, not shown to be Elawady's own words; the archive homepage says the forbidden section is documented 'independently of Dr. Diaa's words'.
Claimed mechanism

Dairy protein/milk increases endogenous IGF-1; IGF-1 promotes prostate cell growth.

Claimed health effect

Prostate cancer.

Population concerned

Men.

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?

Milk raises IGF-1 and IGF-1 raises prostate cancer risk.

2. What is demonstrably correct?

A-DRY-14: moderate evidence that IGF-I rises with milk intake (about 0.10 SD per 1 SD of milk) and that prostate cancer risk rises with IGF-I (OR 1.09 per SD, 1.03-1.16; prospective studies 1.07, 1.02-1.12). I-DRY-06 (IPD, 17 prospective studies): OR 1.29 (1.16-1.43) top vs bottom fifth of IGF-I. The mechanism is biologically plausible.

3. What is wrong or exaggerated?

The effect of milk on IGF-1 is small (about 0.10 SD), was read from albatross plots rather than pooled, and the largest rises came from very small short-term trials in children. IGF-I was not associated with advanced prostate cancer (OR 1.04, 0.94-1.14), the authors state that the evidence that IGF-I increases prostate cancer risk 'is not strong', and they did not test whether IGF-I mediates a dairy-prostate link (A-DRY-14). Calling it 'the mechanism' therefore overstates the evidence. The calf comparison is rhetorical: the IGF-1 increase is mainly the body's own production in response to protein, not 'calf hormone' absorbed from milk (A-DRY-14 discusses circulating levels, not absorption). Other protein sources can also raise IGF-1 (not quantified here). The mechanism also applies to cheese (concentrated milk protein), which the system allows.

4. What remains unclear?

Whether IGF-1 mediates any dairy-prostate association; magnitude of cancer risk attributable to dairy-induced IGF-1; relevance for aggressive disease.

5. Which studies support it?

A-DRY-14, I-DRY-06.

6. Which studies contradict it?

None directly against the two links; limiting: A-DRY-14 itself (no association of IGF-I with advanced prostate cancer; mediation untested).

7. What applies to Germany and Europe?

Not a basis for official recommendations to avoid dairy.

8. What is known about Egypt?

No data.

9. What practical conclusion is appropriate?

A plausible, modest mechanism; it supports moderation of very high dairy-protein intakes rather than elimination of specific dairy types.

Assessment details

Rationale for certainty of evidence

Each link has some support: the archive's own review rates the evidence as moderate that milk raises IGF-I and that IGF-I is associated with prostate cancer (A-DRY-14), and pooled prospective data show OR 1.29 for the top vs bottom fifth of IGF-I (I-DRY-06). But the milk effect on IGF-I (0.10 SD per SD of milk) is a visual estimate, not a pooled result, and comes largely from small short-term trials in children; IGF-I was not associated with advanced prostate cancer; the authors call the IGF-I-prostate cancer evidence 'not strong'; and mediation of a dairy-prostate link by IGF-I was not tested. A mechanism cannot be more certain than the dairy-prostate association it is meant to explain (C-DRY-04: potentially true, low certainty).

Source quality

Archive editorial; figures correctly reported from A-DRY-14.

Regional transferability

Biological; transferable.

Individual exceptions

Children need growth factors; IGF-1 increase with dairy in children is part of normal growth physiology.

Regional scope of the claim
general (biological/medical)
Last reviewed
26 October 2026 provisional

Scientific evidence in detail

Overinterpreted – A real finding exists, but the claim draws more from it than the data allow (e.g. association taken as cause, animal data applied to humans, small effect presented as large).

Research question: Does milk intake raise circulating IGF-1, and does this mediate an increase in prostate cancer risk?

Research question in detail (PECO)
Population
Men (and children for the IGF-1 link)
Intervention or exposure
Milk/dairy intake; circulating IGF-1
Comparison
Lower intake/levels
Geographic scope
universal biology
Outcomes
  • Serum IGF-1
  • Prostate cancer

Study results as reported by the authors. Our assessment follows below.

What speaks for the claim?

What speaks against the claim?

What does the overall evidence say?

Editorial assessment based on the studies above – not itself a study result.

Which position is better supported?

Both links are individually supported (dairy raises IGF-1 modestly; IGF-1 is a likely causal factor for prostate cancer), but evidence that milk-induced IGF-1 changes cause prostate cancer is missing.

Why some studies weigh more

MR on IGF-I strengthens link 2; the null MR for milk weakens the end-to-end chain.

Is a causal relationship established? Possible, not established Each link plausible; mediation not shown.

Remaining uncertainty

Size of diet-induced IGF-1 change in adults; mediation.

Justified conclusion

A plausible mechanism, not a demonstrated one; 'calf hormone' wording is rhetorical (the rise reflects the body's own IGF-1).

Why do studies seem to disagree?

Link-level evidence (I-DRY-110, I-DRY-103) and chain-level evidence (I-DRY-109) differ: a small IGF-1 rise may be too small to produce a detectable prostate effect.

Does this depend on the country?
General biological effects
Universal endocrine physiology.

A regional difference that changes the conclusion is not supported by robust data.

Statistical re-check
  • CI log-symmetry – OK except rounding in 1.05-1.12. recalculated
  • Plausibility of IGF-I effect size – 19.89 nmol/L = ~152 ng/mL: implausible; magnitude not used. recalculated
Certainty of the overall evidence (GRADE, simplified)
Main outcome
Prostate cancer mediated by milk-induced IGF-1
Starting level
low (observational studies)
Reasons for downgrading
  • indirectness (links tested separately)
  • inconsistency (null MR for milk)
Result
low

Simplified assessment by a single reviewer, following the GRADE approach; not a formal GRADE panel. GRADE rates the body of evidence for one outcome, not individual studies.

Clinical guidelines and official statements checked
  • WCRF/AICR: Meat, fish and dairy products and the risk of cancer (CUP 2018) (2018) · Original publication
    Dairy probably protects against colorectal cancer (strong evidence); evidence that dairy (total dairy, milk, cheese, yogurt) increases prostate cancer risk is limited-suggestive; no dairy recommendation made (I-DRY-102).
Search strategy

Documented literature searches for this review (search strings in the original database syntax).

DatabaseDateSearchLooking forHitsIncluded
PubMed26 October 2026("insulin-like growth factor"[ti] OR IGF-1[ti] OR IGF-I[ti]) AND prostate[ti] AND Mendelian[tiab]supporting evidence2
PubMed26 October 2026(dairy[tiab] OR milk[tiab]) AND (child*[tiab] OR adolescen*[tiab]) AND bone[tiab] AND (meta-analysis[pt] OR systematic review[pt])contradicting evidence23
PubMed26 October 2026Larsson SC[au] AND milk[ti] AND Mendelian[ti] AND cancer[ti]contradicting evidence1

Open questions

Mediation analyses; IGF-1 response to dairy in adult men.

How deeply was this checked?

5 linked studies: 2 checked in full text (1 of them with a structured risk-of-bias assessment), 3 on the basis of the abstract, 0 bibliographically only. No formal assessment with two independent reviewers and no independent human expert review has taken place yet.

Last scientific review: 26 October 2026

History of the verdict
  1. 25 October 2026 · Phase 1 · Initial assessment: Mostly true (moderate)
  2. 25 October 2026 · Phase 2 (full-text checks) · Verdict changed: Mostly true (moderate) → Potentially true (low)
    ft1 flag A-DRY-14 accepted with verdict change “Mostly true” -> “Potentially true” and certainty moderate -> low. Reason: full text shows the milk-IGF-I effect is a visual (non-pooled) estimate driven by small child trials, IGF-I is not associated with advanced prostate cancer, the authors call the IGF-I-PCa evidence 'not strong', and mediation was not tested; the claim asserts IGF-1 is 'the mechanism' of a dairy-prostate link that is itself rated “Potentially true”/low (C-DRY-04), so a higher rating for the mechanism is inconsistent. Fairness: both component links remain real and plausible.
  3. 26 October 2026 · Phase 4 (systematic evidence review) · Re-examined with extended evidence; verdict unchanged: Potentially true (low)
    Link-level support is stronger (I-DRY-110 MR, I-DRY-103 RCTs), but the end-to-end causal chain remains unsupported (I-DRY-109). Unchanged.
    New sources: I-DRY-103 I-DRY-109 I-DRY-110

In plain language

Drinking more milk slightly raises the level of a growth hormone called IGF-1 in the blood, and men with higher IGF-1 levels are somewhat more likely to get prostate cancer. The archive's own review rates the evidence for both links as moderate, but says the second link is 'not strong' and found no link with advanced prostate cancer. It has not been shown that IGF-1 is what connects dairy with prostate cancer. Cheese, which the system allows, is rich in the same milk protein.

Studies on this claim

Studies supporting the claim (4)

  • Review: milk slightly raises IGF-1, which is linked to prostate cancer

    Harrison S et al.. Cancer Causes Control 2017 · PMID 28361446 · DOI 10.1007/s10552-017-0883-1
    Systematic reviewcited by the Tayebat archivefull text, structured risk-of-bias assessment★ key study

    IGF-I +0.10 SD per SD of milk; prostate cancer OR 1.09 per SD IGF-I.

    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?

    Test the IGF pathway.

    How was the study done?

    Systematic review of 172 studies.

    How many people, animals or samples were studied?

    Humans and animals.

    What was actually found?

    Moderate evidence for both links, but small effects; IGF-I not associated with advanced prostate cancer.

    How large was the observed effect?

    OR 1.09 (1.03-1.16) per SD IGF-I.

    What do the results mean in everyday life?

    A small, plausible mechanism.

    What are the study's limitations?

    Inference across separate studies; milk-IGF effect only visually estimated; search to 2014.

    What does it say about Elawady's specific claim?

    Supports the mechanism claim, not the size of harm.

    Do the results apply to Germany and Europe?

    Moderate.

    What can explicitly not be concluded from this study?

    That milk causes prostate cancer; the size of any milk-related risk via IGF-1.

    Scientific details →

  • Men with higher IGF-1 levels get prostate cancer somewhat more often

    Travis RC et al.. Cancer Res 2016 · PMID 26921328 · DOI 10.1158/0008-5472.CAN-15-1551
    Meta-analysisindependent cross-checkabstract checked

    Top vs bottom fifth: OR 1.29.

    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?

    IGF and prostate cancer.

    How was the study done?

    IPD meta-analysis.

    How many people, animals or samples were studied?

    10,554 cases.

    What was actually found?

    IGF-I associated.

    How large was the observed effect?

    OR 1.29 (1.16-1.43).

    What do the results mean in everyday life?

    A real but moderate link.

    What are the study's limitations?

    Does not test milk.

    What does it say about Elawady's specific claim?

    Supports mechanism half.

    Do the results apply to Germany and Europe?

    High.

    What can explicitly not be concluded from this study?

    That milk causes cancer.

    Scientific details →

  • Higher IGF-1 linked to prostate cancer, supported by genetics

    Watts EL et al.. Int J Cancer 2021 · PMID 33252839 · DOI 10.1002/ijc.33416
    Cohort studyindependent cross-checkabstract checked

    Per 5 nmol/L IGF-I: 9% higher diagnosis risk; genetic analysis OR 1.34.

    IGF-I -> prostate cancer supported by cohort and MR.

    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?

    Test hormones and prostate cancer.

    How was the study done?

    Cohort plus MR.

    How many people, animals or samples were studied?

    About 200,000 men.

    What was actually found?

    IGF-I and free testosterone linked to higher risk.

    How large was the observed effect?

    HR 1.09 per 5 nmol/L.

    What do the results mean in everyday life?

    IGF-1 is a plausible prostate cancer factor.

    What are the study's limitations?

    Does not test milk.

    What does it say about Elawady's specific claim?

    Supports one link of the mechanism.

    Do the results apply to Germany and Europe?

    UK data.

    What can explicitly not be concluded from this study?

    Cannot show that milk-induced IGF-1 causes cancer.

    Scientific details →

  • Extra dairy helps children build bone

    Hidayat K et al.. Adv Nutr 2023 · PMID 37414219 · DOI 10.1016/j.advnut.2023.06.010
    Meta-analysisindependent cross-checkfull text checked★ key study

    In 21 trials, children given extra dairy gained about 2-4% more bone mineral and grew slightly taller.

    RCT evidence that dairy raises IGF-I (in children; magnitude unreliable).

    Does the study support the specific claim? No · 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?

    Test whether extra dairy improves children's bones.

    How was the study done?

    Meta-analysis of randomised trials.

    How many people, animals or samples were studied?

    21 trials, children 3-18 years.

    What was actually found?

    More bone mineral (about 2-4%), slightly more height, higher IGF-I.

    How large was the observed effect?

    Whole-body BMC +25 g (+3%).

    What do the results mean in everyday life?

    Milk and other dairy help growing bones; removing them needs a calcium plan.

    What are the study's limitations?

    Bone density is a surrogate; some authors work for a dairy company.

    What does it say about Elawady's specific claim?

    Contradicts the idea that milk is harmful for children; confirms that dairy raises IGF-I.

    Do the results apply to Germany and Europe?

    Applies everywhere.

    What can explicitly not be concluded from this study?

    Cannot show fewer fractures later in life.

    Scientific details →

Studies contradicting or limiting the claim (1)

  • Genetic study: milk does not clearly cause prostate cancer but may protect against bowel cancer

    Larsson SC et al.. BMC Med 2020 · PMID 33261611 · DOI 10.1186/s12916-020-01839-9
    Otherindependent cross-checkabstract checked★ key study

    Prostate OR 1.01 (0.99-1.02) per milk allele; colorectal 0.95.

    If milk raised prostate cancer via IGF-1, a genetic milk effect would be expected; overall none found.

    Does the study support the specific claim? No · 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?

    Test cause and effect using genes linked to milk drinking.

    How was the study done?

    Mendelian randomisation.

    How many people, animals or samples were studied?

    Hundreds of thousands of Europeans.

    What was actually found?

    No overall prostate effect; lower bowel cancer.

    How large was the observed effect?

    Prostate OR 1.01.

    What do the results mean in everyday life?

    Milk is unlikely to be a strong cause of prostate cancer.

    What are the study's limitations?

    Instrument limits; milk only.

    What does it say about Elawady's specific claim?

    Weakens the causal claim.

    Do the results apply to Germany and Europe?

    European data.

    What can explicitly not be concluded from this study?

    Cannot exclude a small effect.

    Scientific details →

Studies with mixed or unclear results (0)

No studies in this group.

Regional context

Germany / EU

Not a basis for official recommendations to avoid dairy.

Egypt

No data.

What applies in my country?

General scientific assessment

Potentially true Milk modestly raises IGF-1 and IGF-1 is weakly linked to prostate cancer; this is a plausible but unproven mechanism, not proof of harm.

The following areas of food safety are relevant to this statement:

  • Veterinary medicines and antibiotics
  • Hormonal growth promoters
  • Contaminants (heavy metals, PFAS, PCBs, dioxins, nitrate)
  • Mycotoxins (mould toxins)
  • Controls, imports, recalls, labelling

Dairy

Choose a country to see the checked information for it.

Limits: legal rules describe what is allowed, not what every single food contains. Measurement data come from samples and are meaningful only together with their method details.

Country of residence or purchase Compare with another country

References

  1. Does milk intake promote prostate cancer initiation or progression via effects on insulin-like growth factors (IGFs)? A systematic review and meta-analysis.. Harrison S et al.. Cancer Causes Control 2017 · PMID 28361446 · DOI 10.1007/s10552-017-0883-1
  2. A Meta-analysis of Individual Participant Data Reveals an Association between Circulating Levels of IGF-I and Prostate Cancer Risk.. Travis RC et al.. Cancer Res 2016 · PMID 26921328 · DOI 10.1158/0008-5472.CAN-15-1551
  3. Circulating insulin-like growth factor-I, total and free testosterone concentrations and prostate cancer risk in 200 000 men in UK Biobank.. Watts EL et al.. Int J Cancer 2021 · PMID 33252839 · DOI 10.1002/ijc.33416
  4. The Effects of Dairy Product Supplementation on Bone Health Indices in Children Aged 3 to 18 Years: A Meta-Analysis of Randomized Controlled Trials.. Hidayat K et al.. Adv Nutr 2023 · PMID 37414219 · DOI 10.1016/j.advnut.2023.06.010
  5. Genetically proxied milk consumption and risk of colorectal, bladder, breast, and prostate cancer: a two-sample Mendelian randomization study.. Larsson SC et al.. BMC Med 2020 · PMID 33261611 · DOI 10.1186/s12916-020-01839-9

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