Editing Soybean (section)

== Adverse effects ==

=== Soy allergy ===
{{Main|Soy allergy}}
Allergy to soy is common, and the food is listed with other foods that commonly cause allergy, such as milk, eggs, peanuts, tree nuts, and shellfish. The problem has been reported among younger children, and the diagnosis of soy allergy is often based on symptoms reported by parents and results of skin tests or blood tests for allergy. Only a few reported studies have attempted to confirm allergy to soy by direct challenge with the food under controlled conditions.<ref>{{cite journal |last=Cantani |first=A. |author2=Lucenti P. |date=August 1997 |title=Natural History of Soy Allergy and/or Intolerance in Children, and Clinical Use of Soy-protein Formulas |journal=Pediatric Journal of Allergy and Clinical Immunology |volume=8 |issue=2 |pages=59–74 |doi=10.1111/j.1399-3038.1997.tb00146.x |pmid=9617775 |s2cid=35264190}}<!--the title contains and/or, don't change it--></ref> It is very difficult to give a reliable estimate of the true prevalence of soy allergy in the general population. To the extent that it does exist, soy allergy may cause cases of [[urticaria]] and [[angioedema]], usually within minutes to hours of ingestion. In rare cases, true [[anaphylaxis]] may also occur. The reason for the discrepancy is likely that soy proteins, the causative factor in [[allergy]], are far less potent at triggering allergy symptoms than the proteins of peanut and shellfish.<ref>{{cite journal |last=Cordle |first=C.T. |date=May 2004 |title=Soy Protein Allergy: Incidence and Relative Severity |journal=[[Journal of Nutrition]] |volume=134 |issue=5 |pages=1213S–19S |doi=10.1093/jn/134.5.1213S |pmid=15113974 |doi-access=free}}</ref> An allergy test that is positive demonstrates that the immune system has formed IgE antibodies to soy proteins. However, this is only a factor when soy proteins reach the blood without being digested, in sufficient quantities to reach a threshold to provoke actual symptoms.

Soy can also trigger symptoms via [[food intolerance]], a situation where no allergic mechanism can be proven. One scenario is seen in very young infants who have vomiting and [[Diarrhea|diarrhoea]] when fed soy-based formula, which resolves when the formula is withdrawn. Older infants can suffer a more severe disorder with vomiting, diarrhoea that may be bloody, [[anemia]], weight loss and failure to thrive. The most common cause of this unusual disorder is a sensitivity to cow's milk, but soy formulas can also be the trigger. The precise mechanism is unclear and it could be immunologic, although not through the IgE-type antibodies that have the leading role in urticaria and anaphylaxis. However, it is also self-limiting and will often disappear in the [[toddler]] years.<ref>{{cite journal |last=Sampson |first=H.A. |date=May 1999 |title=Food Allergy, Part 1: Immunopathogenesis and Clinical Disorders |url=http://www.jacionline.org/article/S0091674999704112/pdf |journal=The Journal of Allergy and Clinical Immunology |volume=103 |issue=5 |pages=717–728 |doi=10.1016/S0091-6749(99)70411-2 |pmid=10329801}}</ref>

In the [[European Union]], identifying the presence of soy either as an ingredient or unintended contaminant in packaged food is compulsory. The regulation (EC) 1169/2011 on food-labeling lists 14 allergens, including soy, in packaged food must be clearly indicated on the label as part of the list of ingredients, using a distinctive typography (such as bold type or capital letters).<ref>{{cite web |date=25 October 2011 |title=Regulation (EG) 1169/2011 |url=https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32011R1169 |access-date=7 October 2020 |publisher=Eur-Lex - European Union Law, European Union}}</ref>

===Thyroid function===
One review noted that soy-based foods may inhibit absorption of thyroid hormone medications required for treatment of [[hypothyroidism]].<ref>{{cite journal |last1=Messina |first1=M |last2=Redmond |first2=G |year=2006 |title=Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: A review of the relevant literature |journal=[[Thyroid (journal)|Thyroid]] |volume=16 |issue=3 |pages=249–58 |doi=10.1089/thy.2006.16.249 |pmid=16571087}}</ref> A 2015 scientific review by the [[European Food Safety Authority]] concluded that intake of isoflavones from supplements did not affect thyroid hormone levels in [[postmenopausal]] women.<ref>{{cite journal |year=2015 |title=Risk assessment for peri- and postmenopausal women taking food supplements containing isolated isoflavones |url=https://www.efsa.europa.eu/en/efsajournal/pub/4246 |journal=[[EFSA Journal]] |volume=13 |issue=10 |page=4246 |doi=10.2903/j.efsa.2015.4246 |doi-access=free}}</ref>