Best studies on onion with emphasis on chemical composition, intake, health benefits.

Effect of Quercetin Rich Onion Extracts on Bacterial Quorum Sensing.
Quecan BXV, Santos JTC, Rivera MLC, Hassimotto NMA, Almeida FA, Pinto UM.
Front Microbiol. 2019 Apr 24;10:867. doi: 10.3389/fmicb.2019.00867

Therapeutic effect of topical administration of red onion extract in a murine model of allergic rhinitis.
Seo MY, Kim KR, Lee JJ, Ryu G, Lee SH, Hong SD, Dhong HJ, Baek CH, Chung SK, Kim HY.
Sci Rep. 2019 Feb 27;9(1):2883. doi: 10.1038/s41598-019-39379-9.

Quercetin and Quercetin-Rich Red Onion Extract Alter Pgc-1α Promoter Methylation and Splice Variant Expression.
Devarshi PP, Jones AD, Taylor EM, Stefanska B, Henagan TM.
PPAR Res. 2017;2017:3235693. doi: 10.1155/2017/3235693.

Development of Biocomposites with Antioxidant Activity Based on Red Onion Extract and Acetate Cellulose.
de Dicastillo CL, Navarro R, Guarda A, Galotto MJ.
Antioxidants (Basel). 2015 Aug 3;4(3):533-47. doi: 10.3390/antiox4030533

Identification and Quantification of Flavonoids from Two Southern Italian Cultivars of Allium cepa L., Tropea (Red Onion) and Montoro (Copper Onion), and Their Capacity to Protect Human Erythrocytes from Oxidative Stress.
Tedesco I, Carbone V, Spagnuolo C, Minasi P, Russo GL.
J Agric Food Chem. 2015 Jun 3;63(21):5229-38. doi: 10.1021/acs.jafc.5b01206.

Comparison of the urinary excretion of quercetin glycosides from red onion and aglycone from dietary supplements in healthy subjects: a randomized, single-blinded, cross-over study.
Shi Y, Williamson G.
Food Funct. 2015 May;6(5):1443-8. doi: 10.1039/c5fo00155b.

In vivo effects of dietary quercetin and quercetin-rich red onion extract on skeletal muscle mitochondria, metabolism, and insulin sensitivity.
Henagan TM, Cefalu WT, Ribnicky DM, Noland RC, Dunville K, Campbell WW, Stewart LK, Forney LA, Gettys TW, Chang JS, Morrison CD.
Genes Nutr. 2015 Jan;10(1):451. doi: 10.1007/s12263-014-0451-1.

Effects of raw red onion consumption on metabolic features in overweight or obese women with polycystic ovary syndrome: a randomized controlled clinical trial.
Ebrahimi-Mamaghani M, Saghafi-Asl M, Pirouzpanah S, Asghari-Jafarabadi M.
J Obstet Gynaecol Res. 2014 Apr;40(4):1067-76. doi: 10.1111/jog.12311

The onion (Allium cepa L.), white or red, belongs to the family of Liliaceae.

The onion contains flavonoids, very useful to the human body as robust antioxidants found in the outermost layers.

It should be eaten raw so as not to lose the healing properties of flavonoids and sulfur derivatives present in this vegetable.

Animal studies have shown the effectiveness of onion as an anticoagulant.

Human studies have found the usefulness of onion combined with other vegetables to prevent cardiovascular problems.

As an anti-inflammatory, a component of the onion, Onionin A found in the bulb, has been shown to perform an action to counteract inflammatory blood activity (1).

There would also appear to be an action to improve the balance of blood sugar.

It is recommended, along with garlic, shallots and chives to prevent prostate cancer (2).

The best known red onions in Italy are the red head of Tropea and Certaldo.

Red onion studies

References_____________________________________________________________________

(1) Fujiwara Y, Horlad H, Shiraishi D, Tsuboki J, Kudo R, Ikeda T, Nohara T, Takeya M, Komohara Y. Onionin A, a sulfur-containing compound isolated from onions, impairs tumor development and lung metastasis by inhibiting the protumoral and immunosuppressive functions of myeloid cells.  Mol Nutr Food Res. 2016 Nov;60(11):2467-2480. doi: 10.1002/mnfr.201500995.

(2) Colli JL, Amling CL. Chemoprevention of prostate cancer: what can be recommended to patients?  Curr Urol Rep. 2009 May;10(3):165-71. Review.