Soy phyto-oestrogens reach hormonally concerning levels in infants fed soy formula (6-11 fold the hormonally active adult dose; plasma isoflavones 13,000-22,000 times oestradiol).

Original statement

No Arabic original wording available.

Translation

Soy phyto-oestrogens reach hormonally concerning levels in infants fed soy formula (6-11 fold the hormonally active adult dose; plasma isoflavones 13,000-22,000 times oestradiol).

Origin

Source status

Archive editors

Attribution

Archive editors

Origin

https://eltayebat.com/rule/legumes/

Attribution uncertainty

Archive editorial text and study selection written by the archive operators, not necessarily by Elawady.

Claimed mechanism

Isoflavones (genistein, daidzein) bind oestrogen receptors; goitrogenic effects with iodine deficiency.

Claimed health effect

Possible hormonal/developmental effects in infants.

Population concerned

Infants fed soy-based formula

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?

Soy formula exposes infants to hormonally relevant isoflavone levels.

2. What is demonstrably correct?

The exposure figures are correctly cited from Setchell 1997; altered vaginal-cell DNA methylation was observed in soy-fed girls (Harlid 2017).

3. What is wrong or exaggerated?

Exposure does not equal harm. The retrospective cohort by Strom 2001 found no significant differences in general or reproductive health in young adulthood, except slightly longer menstrual bleeding (0.37 days) and more menstrual discomfort. The finding concerns infant soy formula, not legumes eaten by children or adults, and not fava beans or lentils.

4. What remains unclear?

Long-term effects of the epigenetic and subtle tissue changes are unknown.

5. Which studies support it?

Setchell 1997 (exposure); Doerge & Sheehan 2002 (mechanistic, animal); Upson 2019 (I-LEG-130: menstrual pain indicators RR 1.4-1.5 in women fed soy formula as infants); Upson 2016 (I-LEG-131: no more fibroids, but larger fibroids). Harlid 2017 (A-LEG-09) is weak and indirect: it measured no isoflavone levels, its discovery scan (10 infants) was uncorrected and age-imbalanced, the overall methylation trajectory did not differ (p=0.25), and the authors state the data are not a clear contraindication to soy formula.

6. Which studies contradict it?

Strom 2001 (I-LEG-10); Andres 2015 (I-LEG-129: no differences in reproductive organs at age 5).

7. What applies to Germany and Europe?

ESPGHAN (I-LEG-132) states that soy formula has no nutritional advantage and that its phytoestrogens 'might have untoward effects'; it restricts use to specific indications (e.g. galactosaemia, severe lactose intolerance, vegan choice).

8. What is known about Egypt?

Not specific.

9. What practical conclusion is appropriate?

Soy formula should not be used without an indication in young infants; this does not support avoiding legumes in general.

Assessment details

Rationale for certainty of evidence

Exposure data are solid (Setchell 1997, n=7 per group); epigenetic changes in a small study (Harlid 2017); but long-term follow-up (Strom 2001, 248 soy vs 563 cow-milk formula) found no differences in >30 outcomes except slightly longer menstrual bleeding and more discomfort. Clinical significance remains uncertain.

Source quality

Archive cites exposure and mechanistic studies; omits the reassuring long-term cohort.

Regional transferability

Soy formula is used for specific indications in Europe; not directly relevant to adult consumption of fava beans or lentils (which are not soy).

Individual exceptions

Infants with cow-milk protein allergy may receive soy formula only on medical advice.

Regional scope of the claim

not specified

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: Do infants fed soy-based formula reach phytoestrogen exposures that cause clinically relevant hormonal or reproductive effects later in life?

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

Open questions

Pubertal outcomes (Beginnings follow-up).

How deeply was this checked?

9 linked studies: 1 checked in full text (1 of them with a structured risk-of-bias assessment), 8 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

In plain language

Babies fed soy-based formula take in large amounts of plant oestrogens relative to their body weight, and some subtle biological changes have been measured. A long-term study of adults who were fed soy formula as babies found no major health differences, apart from slightly longer periods in women. The question concerns infant formula only and says nothing about fava beans or lentils.

Studies on this claim

Regional context

Germany / EU

ESPGHAN (I-LEG-132) states that soy formula has no nutritional advantage and that its phytoestrogens 'might have untoward effects'; it restricts use to specific indications (e.g. galactosaemia, severe lactose intolerance, vegan choice).

Egypt

Not specific.

• Aflatoxins in groundnuts (peanuts)
• G6PD deficiency and favism (fava beans)

What applies in my country?

General scientific assessment

Potentially true High infant exposure is documented; clinical harm is uncertain, and it is irrelevant to other legumes.

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

• Pesticides and pesticide residues
• Contaminants (heavy metals, PFAS, PCBs, dioxins, nitrate)
• Mycotoxins (mould toxins)

Legumes and nuts

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. Exposure of infants to phyto-oestrogens from soy-based infant formula.. Setchell KD et al.. Lancet 1997 · PMID 9217716 · DOI 10.1016/S0140-6736(96)09480-9
2. Soy-based infant formula feeding and menstrual pain in a cohort of women aged 23-35 years.. Upson K et al.. Hum Reprod 2019 · PMID 30412246 · DOI 10.1093/humrep/dey303
3. Exposure to soy-based formula in infancy and endocrinological and reproductive outcomes in young adulthood.. Strom BL et al.. JAMA 2001 · PMID 11497534 · DOI 10.1001/jama.286.7.807
4. Compared with feeding infants breast milk or cow-milk formula, soy formula feeding does not affect subsequent reproductive organ size at 5 years of age.. Andres A et al.. J Nutr 2015 · PMID 25761499 · DOI 10.3945/jn.114.206201
5. Goitrogenic and estrogenic activity of soy isoflavones.. Doerge DR, Sheehan DM. Environ Health Perspect 2002 · PMID 12060828 · DOI 10.1289/ehp.02110s3349
6. Soy Formula and Epigenetic Modifications: Analysis of Vaginal Epithelial Cells from Infant Girls in the IFED Study.. Harlid S et al.. Environ Health Perspect 2017 · PMID 27539829 · DOI 10.1289/EHP428
7. Soy-Based Infant Formula Feeding and Ultrasound-Detected Uterine Fibroids among Young African-American Women with No Prior Clinical Diagnosis of Fibroids.. Upson K et al.. Environ Health Perspect 2016 · PMID 26565393 · DOI 10.1289/ehp.1510082
8. Soy protein infant formulae and follow-on formulae: a commentary by the ESPGHAN Committee on Nutrition.. ESPGHAN Committee on Nutrition. J Pediatr Gastroenterol Nutr 2006 · PMID 16641572 · DOI 10.1097/01.mpg.0000189358.38427.cd
9. Use of soy protein-based formulas in infant feeding.. Bhatia J, Greer F. Pediatrics 2008 · PMID 18450914 · DOI 10.1542/peds.2008-0564